Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
5.8
3.4
Journals
Materials
Editor’s Choice
materials-logo

Journal Menu

► Journal Menu

Journal Browser

► Journal Browser
share announcement

Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

Order results
Result details
Results per page
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
14 pages, 3476 KiB  
Article
Bismuth−Antimony Alloy Embedded in Carbon Matrix for Ultra-Stable Sodium Storage
by Wensheng Ma, Bin Yu, Fuquan Tan, Hui Gao and Zhonghua Zhang
Materials 2023, 16(6), 2189; https://doi.org/10.3390/ma16062189 - 9 Mar 2023
Cited by 2 | Viewed by 1667
Abstract
Alloy-type anodes are the most promising candidates for sodium-ion batteries (SIBs) due to their impressive Na storage capacity and suitable voltage platform. However, the implementation of alloy-type anodes is significantly hindered by their huge volume expansion during the alloying/dealloying processes, which leads to [...] Read more.
Alloy-type anodes are the most promising candidates for sodium-ion batteries (SIBs) due to their impressive Na storage capacity and suitable voltage platform. However, the implementation of alloy-type anodes is significantly hindered by their huge volume expansion during the alloying/dealloying processes, which leads to their pulverization and detachment from current collectors for active materials and the unsatisfactory cycling performance. In this work, bimetallic Bi−Sb solid solutions in a porous carbon matrix are synthesized by a pyrolysis method as anode material for SIBs. Adjustable alloy composition, the introduction of porous carbon matrix, and nanosized bimetallic particles effectively suppress the volume change during cycling and accelerate the electrons/ions transport kinetics. The optimized Bi1Sb1@C electrode exhibits an excellent electrochemical performance with an ultralong cycle life (167.2 mAh g−1 at 1 A g−1 over 8000 cycles). In situ X-ray diffraction investigation is conducted to reveal the reversible and synchronous sodium storage pathway of the Bi1Sb1@C electrode: (Bi,Sb) Na(Bi,Sb) Na3(Bi,Sb). Furthermore, online electrochemical mass spectrometry unveils the evolution of gas products of the Bi1Sb1@C electrode during the cell operation. Full article
(This article belongs to the Special Issue Advanced Electrode Materials for Batteries)
►▼ Show Figures

Figure 1

14 pages, 3306 KiB  
Article
Deashed Wheat-Straw Biochar as a Potential Superabsorbent for Pesticides
by Irmina Ćwieląg-Piasecka, Elżbieta Jamroz, Agnieszka Medyńska-Juraszek, Magdalena Bednik, Bogna Kosyk and Nora Polláková
Materials 2023, 16(6), 2185; https://doi.org/10.3390/ma16062185 - 9 Mar 2023
Cited by 10 | Viewed by 2440
Abstract
Biochar activation methods have attracted extensive attention due to their great role in improving sorptive properties of carbon-based materials. As a result, chemically modified biochars gained application potential in the purification of soil and water from xenobiotics. This paper describes changes in selected [...] Read more.
Biochar activation methods have attracted extensive attention due to their great role in improving sorptive properties of carbon-based materials. As a result, chemically modified biochars gained application potential in the purification of soil and water from xenobiotics. This paper describes changes in selected physicochemical properties of high-temperature wheat-straw biochar (BC) upon its deashing. On the pristine and chemically activated biochar (BCd) retention of five pesticides of endocrine disrupting activity (carbaryl, carbofuran, 2,4-D, MCPA and metolachlor) was studied. Deashing resulted in increased sorbent aromaticity and abundance in surface hydroxyl groups. BCd exhibited more developed meso- and microporosity and nearly triple the surface area of BC. Hydrophobic pesticides (metolachlor and carbamates) displayed comparably high (88–98%) and irreversible adsorption on both BCs, due to the pore filling, whereas the hydrophilic and ionic phenoxyacetic acids were weakly and reversibly sorbed on BC (7.3 and 39% of 2,4-D and MCPA dose introduced). Their removal from solution and hence retention on the deashed biochar was nearly total, due to the increased sorbent surface area and interactions of the agrochemicals with unclogged OH groups. The modified biochar has the potential to serve as a superabsorbent, immobilizing organic pollutant of diverse hydrophobicity from water and soil solution. Full article
(This article belongs to the Special Issue Biochar and Carbon-Based Materials: Properties and Applications)
►▼ Show Figures

Figure 1

16 pages, 22247 KiB  
Article
Effect of Gd3+, La3+, Lu3+ Co-Doping on the Morphology and Luminescent Properties of NaYF4:Sm3+ Phosphors
by Viktor G. Nosov, Anna A. Betina, Tatyana S. Bulatova, Polina B. Guseva, Ilya E. Kolesnikov, Sergey N. Orlov, Maxim S. Panov, Mikhail N. Ryazantsev, Nikita A. Bogachev, Mikhail Yu Skripkin and Andrey S. Mereshchenko
Materials 2023, 16(6), 2157; https://doi.org/10.3390/ma16062157 - 7 Mar 2023
Cited by 1 | Viewed by 2063
Abstract
The series of luminescent NaYF4:Sm3+ nano- and microcrystalline materials co-doped by La3+, Gd3+, and Lu3+ ions were synthesized by hydrothermal method using rare earth chlorides as the precursors and citric acid as a stabilizing agent. [...] Read more.
The series of luminescent NaYF4:Sm3+ nano- and microcrystalline materials co-doped by La3+, Gd3+, and Lu3+ ions were synthesized by hydrothermal method using rare earth chlorides as the precursors and citric acid as a stabilizing agent. The phase composition of synthesized compounds was studied by PXRD. All synthesized materials except ones with high La3+ content (where LaF3 is formed) have a β-NaYF4 crystalline phase. SEM images demonstrate that all particles have shape of hexagonal prisms. The type and content of doping REE significantly effect on the particle size. Upon 400 nm excitation, phosphors exhibit distinct emission peaks in visible part of the spectrum attributed to 4G5/2→6HJ transitions (J = 5/2–11/2) of Sm3+ ion. Increasing the samarium (III) content results in concentration quenching by dipole–dipole interactions, the optimum Sm3+concentration is found to be of 2%. Co-doping by non-luminescent La3+, Gd3+ and Lu3+ ions leads to an increase in emission intensity. This effect was explained from the Sm3+ local symmetry point of view. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Optical and Photonic Materials)
►▼ Show Figures

Figure 1

11 pages, 3967 KiB  
Article
Preparation of Hydrogel Composites Using a Sustainable Approach for In Situ Silver Nanoparticles Formation
by Laura Chronopoulou, Roya Binaymotlagh, Sara Cerra, Farid Hajareh Haghighi, Enea Gino Di Domenico, Francesca Sivori, Ilaria Fratoddi, Silvano Mignardi and Cleofe Palocci
Materials 2023, 16(6), 2134; https://doi.org/10.3390/ma16062134 - 7 Mar 2023
Cited by 7 | Viewed by 1592
Abstract
The recognized antibacterial properties of silver nanoparticles (AgNPs) characterize them as attractive nanomaterials for developing new bioactive materials less prone to the development of antibiotic resistance. In this work, we developed new composites based on self-assembling Fmoc-Phe3 peptide hydrogels impregnated with in situ [...] Read more.
The recognized antibacterial properties of silver nanoparticles (AgNPs) characterize them as attractive nanomaterials for developing new bioactive materials less prone to the development of antibiotic resistance. In this work, we developed new composites based on self-assembling Fmoc-Phe3 peptide hydrogels impregnated with in situ prepared AgNPs. Different methodologies, from traditional to innovative and eco-sustainable, were compared. The obtained composites were characterized from a hydrodynamic, structural, and morphological point of view, using different techniques such as DLS, SEM, and rheological measurements to evaluate how the choice of the reducing agent determines the characteristics of AgNPs and how their presence within the hydrogel affects their structure and properties. Moreover, the antibacterial properties of these composites were tested against S. aureus, a major human pathogen responsible for a wide range of clinical infections. Results demonstrated that the hydrogel composites containing AgNPs (hgel@AgNPs) could represent promising biomaterials for treating S. aureus-related infections. Full article
(This article belongs to the Special Issue New Advances in Nanomaterials)
►▼ Show Figures

Figure 1

26 pages, 10631 KiB  
Article
Production of Nano Hydroxyapatite and Mg-Whitlockite from Biowaste-Derived products via Continuous Flow Hydrothermal Synthesis: A Step towards Circular Economy
by Farah Nigar, Amy-Louise Johnston, Jacob Smith, William Oakley, Md Towhidul Islam, Reda Felfel, David Grant, Edward Lester and Ifty Ahmed
Materials 2023, 16(6), 2138; https://doi.org/10.3390/ma16062138 - 7 Mar 2023
Cited by 5 | Viewed by 2422
Abstract
Biowastes from agriculture, sewage, household wastes, and industries comprise promising resources to produce biomaterials while reducing adverse environmental effects. This study focused on utilising waste-derived materials (i.e., eggshells as a calcium source, struvite as a phosphate source, and CH3COOH as dissolution [...] Read more.
Biowastes from agriculture, sewage, household wastes, and industries comprise promising resources to produce biomaterials while reducing adverse environmental effects. This study focused on utilising waste-derived materials (i.e., eggshells as a calcium source, struvite as a phosphate source, and CH3COOH as dissolution media) to produce value-added products (i.e., calcium phosphates (CaPs) derived from biomaterials) using a continuous flow hydrothermal synthesis route. The prepared materials were characterised via XRD, FEG-SEM, EDX, FTIR, and TEM analysis. Magnesium whitlockite (Mg-WH) and hydroxyapatite (HA) were produced by single-phase or biphasic CaPs by reacting struvite with either calcium nitrate tetrahydrate or an eggshell solution at 200 °C and 350 °C. Rhombohedral-shaped Mg-WH (23–720 nm) along with tube (50–290 nm diameter, 20–71 nm thickness) and/or ellipsoidal morphologies of HA (273–522 nm width) were observed at 350 °C using HNO3 or CH3COOH to prepare the eggshell and struvite solutions, and NH4OH was used as the pH buffer. The Ca/P (atomic%) ratios obtained ranged between 1.3 and 1.7, indicating the formation of Mg-WH and HA. This study showed that eggshells and struvite usage, along with CH3COOH, are promising resources as potential sustainable precursors and dissolution media, respectively, to produce CaPs with varying morphologies. Full article
(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)
►▼ Show Figures

Graphical abstract

14 pages, 4881 KiB  
Article
Inductive Determination of Rate-Reaction Equation Parameters for Dislocation Structure Formation Using Artificial Neural Network
by Yoshitaka Umeno, Emi Kawai, Atsushi Kubo, Hiroyuki Shima and Takashi Sumigawa
Materials 2023, 16(5), 2108; https://doi.org/10.3390/ma16052108 - 5 Mar 2023
Cited by 4 | Viewed by 1335
Abstract
The reaction–diffusion equation approach, which solves differential equations of the development of density distributions of mobile and immobile dislocations under mutual interactions, is a method widely used to model the dislocation structure formation. A challenge in the approach is the difficulty in the [...] Read more.
The reaction–diffusion equation approach, which solves differential equations of the development of density distributions of mobile and immobile dislocations under mutual interactions, is a method widely used to model the dislocation structure formation. A challenge in the approach is the difficulty in the determination of appropriate parameters in the governing equations because deductive (bottom-up) determination for such a phenomenological model is problematic. To circumvent this problem, we propose an inductive approach utilizing the machine-learning method to search a parameter set that produces simulation results consistent with experiments. Using a thin film model, we performed numerical simulations based on the reaction–diffusion equations for various sets of input parameters to obtain dislocation patterns. The resulting patterns are represented by the following two parameters; the number of dislocation walls (p2), and the average width of the walls (p3). Then, we constructed an artificial neural network (ANN) model to map between the input parameters and the output dislocation patterns. The constructed ANN model was found to be able to predict dislocation patterns; i.e., average errors in p2 and p3 for test data having 10% deviation from the training data were within 7% of the average magnitude of p2 and p3. The proposed scheme enables us to find appropriate constitutive laws that lead to reasonable simulation results, once realistic observations of the phenomenon in question are provided. This approach provides a new scheme to bridge models for different length scales in the hierarchical multiscale simulation framework. Full article
(This article belongs to the Section Materials Simulation and Design)
►▼ Show Figures

Figure 1

34 pages, 11195 KiB  
Review
Review of Recent Advances in Gas-Assisted Focused Ion Beam Time-of-Flight Secondary Ion Mass Spectrometry (FIB-TOF-SIMS)
by Agnieszka Priebe and Johann Michler
Materials 2023, 16(5), 2090; https://doi.org/10.3390/ma16052090 - 3 Mar 2023
Cited by 9 | Viewed by 4089
Abstract
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a powerful chemical characterization technique allowing for the distribution of all material components (including light and heavy elements and molecules) to be analyzed in 3D with nanoscale resolution. Furthermore, the sample’s surface can be probed over [...] Read more.
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a powerful chemical characterization technique allowing for the distribution of all material components (including light and heavy elements and molecules) to be analyzed in 3D with nanoscale resolution. Furthermore, the sample’s surface can be probed over a wide analytical area range (usually between 1 µm2 and 104 µm2) providing insights into local variations in sample composition, as well as giving a general overview of the sample’s structure. Finally, as long as the sample’s surface is flat and conductive, no additional sample preparation is needed prior to TOF-SIMS measurements. Despite many advantages, TOF-SIMS analysis can be challenging, especially in the case of weakly ionizing elements. Furthermore, mass interference, different component polarity of complex samples, and matrix effect are the main drawbacks of this technique. This implies a strong need for developing new methods, which could help improve TOF-SIMS signal quality and facilitate data interpretation. In this review, we primarily focus on gas-assisted TOF-SIMS, which has proven to have potential for overcoming most of the aforementioned difficulties. In particular, the recently proposed use of XeF2 during sample bombardment with a Ga+ primary ion beam exhibits outstanding properties, which can lead to significant positive secondary ion yield enhancement, separation of mass interference, and inversion of secondary ion charge polarity from negative to positive. The implementation of the presented experimental protocols can be easily achieved by upgrading commonly used focused ion beam/scanning electron microscopes (FIB/SEM) with a high vacuum (HV)-compatible TOF-SIMS detector and a commercial gas injection system (GIS), making it an attractive solution for both academic centers and the industrial sectors. Full article
(This article belongs to the Special Issue Advances in Elemental Characterization of Materials and Mass Spectrometry Technique Development)
►▼ Show Figures

Figure 1

14 pages, 2432 KiB  
Article
Influence of Sintering Conditions and Nanosilicon Carbide Concentration on the Mechanical and Thermal Properties of Si3N4-Based Materials
by Magdalena Gizowska, Milena Piątek, Krzysztof Perkowski and Agnieszka Antosik
Materials 2023, 16(5), 2079; https://doi.org/10.3390/ma16052079 - 3 Mar 2023
Cited by 1 | Viewed by 1666
Abstract
In the work, silicon nitride ceramics (Si3N4) and silicon nitride reinforced by nano silicon carbide particles (Si3N4-nSiC) in amounts of 1–10 wt.% were investigated. The materials were obtained using two sintering regimes: under conditions of [...] Read more.
In the work, silicon nitride ceramics (Si3N4) and silicon nitride reinforced by nano silicon carbide particles (Si3N4-nSiC) in amounts of 1–10 wt.% were investigated. The materials were obtained using two sintering regimes: under conditions of ambient and high isostatic pressure. The influence of the sintering conditions and the concentration of nanosilicon carbide particles on the thermal and mechanical properties was studied. The presence of highly conductive silicon carbide particles caused an increase in thermal conductivity only in the case of the composites containing 1 wt.% of the carbide phase (15.6 W·m−1·K−1) in comparison with silicon nitride ceramics (11.4 W·m−1·K−1) obtained under the same conditions. With the increase in the carbide phase, a decrease in the densification efficiency during sintering was observed, which caused a decrease in thermal and mechanical performance. The sintering performed using a hot isostatic press (HIP) proved to be beneficial in terms of mechanical properties. The one-step high-pressure assisted sintering process in the HIP minimizes the formation of defects at the sample surface. Full article
(This article belongs to the Special Issue New Studies in Ceramics: Synthesis, Sintering, Characterization and Potential Applications)
►▼ Show Figures

Figure 1

16 pages, 2511 KiB  
Article
Exploring Structure-Sensitive Factors Relevant to Cryogenic Laser Operation in Oxide Crystals Doped with Er3+ Ions
by Witold Ryba-Romanowski, Radoslaw Lisiecki, Jaroslaw Komar, Boguslaw Macalik and Marek Berkowski
Materials 2023, 16(5), 2095; https://doi.org/10.3390/ma16052095 - 3 Mar 2023
Cited by 1 | Viewed by 1181
Abstract
Crystals of Gd3Al2.5Ga2.5O12:Er3+, (Lu0.3Gd0.7)2SiO5:Er3+ and LiNbO3:Er3+ compounds differing in origin and the nature of their inherent structural disorder were crystalized. Optical [...] Read more.
Crystals of Gd3Al2.5Ga2.5O12:Er3+, (Lu0.3Gd0.7)2SiO5:Er3+ and LiNbO3:Er3+ compounds differing in origin and the nature of their inherent structural disorder were crystalized. Optical absorption and luminescence spectra for transitions between the 4I15/2 and the 4I13/2 multiplets of Er3+ ions for the crystal samples were recorded versus temperatures in the region of 80–300 K. Gathered data were analyzed thoroughly providing the in-depth knowledge of the effects of temperature on intensities, wavelengths and bandwidths of Er3+ transitions. The information acquired together with the knowledge of significant structural dissimilarities of the host crystals chosen made it possible to propose an interpretation of the impact of a structural disorder in Er3+-doped crystals on their spectroscopic properties, and to determine their lasing ability at cryogenic temperatures upon resonant (in-band) optical pumping. Full article
(This article belongs to the Special Issue Luminescent Properties of Materials and Their Applications)
►▼ Show Figures

Figure 1

23 pages, 14088 KiB  
Article
Influence of Waste Glass Particle Size on the Physico-Mechanical Properties and Porosity of Foamed Geopolymer Composites Based on Coal Fly Ash
by Celina Ziejewska, Agnieszka Grela and Marek Hebda
Materials 2023, 16(5), 2044; https://doi.org/10.3390/ma16052044 - 1 Mar 2023
Cited by 4 | Viewed by 2137
Abstract
In order to protect the environment and counteract climate change, it is necessary to take any actions that enable a reduction in CO2 emissions. One of the key areas is research focused on developing alternative sustainable materials for construction to reduce the [...] Read more.
In order to protect the environment and counteract climate change, it is necessary to take any actions that enable a reduction in CO2 emissions. One of the key areas is research focused on developing alternative sustainable materials for construction to reduce the global demand for cement. This work presents the properties of foamed geopolymers with the addition of waste glass as well as determined the optimal size and amount of waste glass for improving the mechanical and physical features of the produced composites. Several geopolymer mixtures were fabricated by replacing coal fly ash with 0%, 10%, 20%, and 30% of waste glass by weight. Moreover, the effect of using different particle size ranges of the addition (0.1–1200 µm; 200–1200 µm; 100–250 µm; 63–120 µm; 40–63 µm; 0.1–40 µm) in the geopolymer matrix was examined. Based on the results, it was found that the application of 20–30% of waste glass with a particle size range of 0.1–1200 µm and a mean diameter of 550 µm resulted in approximately 80% higher compressive strength in comparison to unmodified material. Moreover, the samples produced using the smallest fraction (0.1–40 µm) of waste glass in the amount of 30% reached the highest specific surface area (43.711 m2/g), maximum porosity (69%), and density of 0.6 g/cm3. Full article
(This article belongs to the Special Issue New Trends in Geopolymer Concrete)
►▼ Show Figures

Figure 1

18 pages, 2781 KiB  
Review
Direct Imaging of the Kinetic Crystallization Pathway: Simulation and Liquid-Phase Transmission Electron Microscopy Observations
by Zhangying Xu and Zihao Ou
Materials 2023, 16(5), 2026; https://doi.org/10.3390/ma16052026 - 1 Mar 2023
Cited by 2 | Viewed by 2786
Abstract
The crystallization of materials from a suspension determines the structure and function of the final product, and numerous pieces of evidence have pointed out that the classical crystallization pathway may not capture the whole picture of the crystallization pathways. However, visualizing the initial [...] Read more.
The crystallization of materials from a suspension determines the structure and function of the final product, and numerous pieces of evidence have pointed out that the classical crystallization pathway may not capture the whole picture of the crystallization pathways. However, visualizing the initial nucleation and further growth of a crystal at the nanoscale has been challenging due to the difficulties of imaging individual atoms or nanoparticles during the crystallization process in solution. Recent progress in nanoscale microscopy had tackled this problem by monitoring the dynamic structural evolution of crystallization in a liquid environment. In this review, we summarized several crystallization pathways captured by the liquid-phase transmission electron microscopy technique and compared the observations with computer simulation. Apart from the classical nucleation pathway, we highlight three nonclassical pathways that are both observed in experiments and computer simulations: formation of an amorphous cluster below the critical nucleus size, nucleation of the crystalline phase from an amorphous intermediate, and transition between multiple crystalline structures before achieving the final product. Among these pathways, we also highlight the similarities and differences between the experimental results of the crystallization of single nanocrystals from atoms and the assembly of a colloidal superlattice from a large number of colloidal nanoparticles. By comparing the experimental results with computer simulations, we point out the importance of theory and simulation in developing a mechanistic approach to facilitate the understanding of the crystallization pathway in experimental systems. We also discuss the challenges and future perspectives for investigating the crystallization pathways at the nanoscale with the development of in situ nanoscale imaging techniques and potential applications to the understanding of biomineralization and protein self-assembly. Full article
(This article belongs to the Special Issue Self-Assembly and Non-equilibrium Behaviors in Soft Matter Systems)
►▼ Show Figures

Figure 1

30 pages, 1782 KiB  
Review
FRP-Reinforced/Strengthened Concrete: State-of-the-Art Review on Durability and Mechanical Effects
by Jesús D. Ortiz, Seyed Saman Khedmatgozar Dolati, Pranit Malla, Antonio Nanni and Armin Mehrabi
Materials 2023, 16(5), 1990; https://doi.org/10.3390/ma16051990 - 28 Feb 2023
Cited by 20 | Viewed by 5421
Abstract
Fiber-reinforced polymer (FRP) composites have gained increasing recognition and application in the field of civil engineering in recent decades due to their notable mechanical properties and chemical resistance. However, FRP composites may also be affected by harsh environmental conditions (e.g., water, alkaline solutions, [...] Read more.
Fiber-reinforced polymer (FRP) composites have gained increasing recognition and application in the field of civil engineering in recent decades due to their notable mechanical properties and chemical resistance. However, FRP composites may also be affected by harsh environmental conditions (e.g., water, alkaline solutions, saline solutions, elevated temperature) and exhibit mechanical phenomena (e.g., creep rupture, fatigue, shrinkage) that could affect the performance of the FRP reinforced/strengthened concrete (FRP-RSC) elements. This paper presents the current state-of-the-art on the key environmental and mechanical conditions affecting the durability and mechanical properties of the main FRP composites used in reinforced concrete (RC) structures (i.e., Glass/vinyl-ester FRP bars and Carbon/epoxy FRP fabrics for internal and external application, respectively). The most likely sources and their effects on the physical/mechanical properties of FRP composites are highlighted herein. In general, no more than 20% tensile strength was reported in the literature for the different exposures without combined effects. Additionally, some provisions for the serviceability design of FRP-RSC elements (e.g., environmental factors, creep reduction factor) are examined and commented upon to understand the implications of the durability and mechanical properties. Furthermore, the differences in serviceability criteria for FRP and steel RC elements are highlighted. Through familiarity with their behavior and effects on enhancing the long-term performance of RSC elements, it is expected that the results of this study will help in the proper use of FRP materials for concrete structures. Full article
(This article belongs to the Section Advanced Composites)
►▼ Show Figures

Figure 1

17 pages, 6463 KiB  
Review
Hexagonal Boron Nitride for Photonic Device Applications: A Review
by Shinpei Ogawa, Shoichiro Fukushima and Masaaki Shimatani
Materials 2023, 16(5), 2005; https://doi.org/10.3390/ma16052005 - 28 Feb 2023
Cited by 9 | Viewed by 5710
Abstract
Hexagonal boron nitride (hBN) has emerged as a key two-dimensional material. Its importance is linked to that of graphene because it provides an ideal substrate for graphene with minimal lattice mismatch and maintains its high carrier mobility. Moreover, hBN has unique properties in [...] Read more.
Hexagonal boron nitride (hBN) has emerged as a key two-dimensional material. Its importance is linked to that of graphene because it provides an ideal substrate for graphene with minimal lattice mismatch and maintains its high carrier mobility. Moreover, hBN has unique properties in the deep ultraviolet (DUV) and infrared (IR) wavelength bands owing to its indirect bandgap structure and hyperbolic phonon polaritons (HPPs). This review examines the physical properties and applications of hBN-based photonic devices that operate in these bands. A brief background on BN is provided, and the theoretical background of the intrinsic nature of the indirect bandgap structure and HPPs is discussed. Subsequently, the development of DUV-based light-emitting diodes and photodetectors based on hBN’s bandgap in the DUV wavelength band is reviewed. Thereafter, IR absorbers/emitters, hyperlenses, and surface-enhanced IR absorption microscopy applications using HPPs in the IR wavelength band are examined. Finally, future challenges related to hBN fabrication using chemical vapor deposition and techniques for transferring hBN to a substrate are discussed. Emerging techniques to control HPPs are also examined. This review is intended to assist researchers in both industry and academia in the design and development of unique hBN-based photonic devices operating in the DUV and IR wavelength regions. Full article
(This article belongs to the Special Issue Research Progress on Two-Dimensional Materials)
►▼ Show Figures

Figure 1

27 pages, 19024 KiB  
Article
Temperature Field, Flow Field, and Temporal Fluctuations Thereof in Ammonothermal Growth of Bulk GaN—Transition from Dissolution Stage to Growth Stage Conditions
by Saskia Schimmel, Daisuke Tomida, Tohru Ishiguro, Yoshio Honda, Shigefusa F. Chichibu and Hiroshi Amano
Materials 2023, 16(5), 2016; https://doi.org/10.3390/ma16052016 - 28 Feb 2023
Cited by 3 | Viewed by 1914
Abstract
With the ammonothermal method, one of the most promising technologies for scalable, cost-effective production of bulk single crystals of the wide bandgap semiconductor GaN is investigated. Specifically, etch-back and growth conditions, as well as the transition from the former to the latter, are [...] Read more.
With the ammonothermal method, one of the most promising technologies for scalable, cost-effective production of bulk single crystals of the wide bandgap semiconductor GaN is investigated. Specifically, etch-back and growth conditions, as well as the transition from the former to the latter, are studied using a 2D axis symmetrical numerical model. In addition, experimental crystal growth results are analyzed in terms of etch-back and crystal growth rates as a function of vertical seed position. The numerical results of internal process conditions are discussed. Variations along the vertical axis of the autoclave are analyzed using both numerical and experimental data. During the transition from quasi-stable conditions of the dissolution stage (etch-back process) to quasi-stable conditions of the growth stage, significant temperature differences of 20 K to 70 K (depending on vertical position) occur temporarily between the crystals and the surrounding fluid. These lead to maximum rates of seed temperature change of 2.5 K/min to 1.2 K/min depending on vertical position. Based on temperature differences between seeds, fluid, and autoclave wall upon the end of the set temperature inversion process, deposition of GaN is expected to be favored on the bottom seed. The temporarily observed differences between the mean temperature of each crystal and its fluid surrounding diminish about 2 h after reaching constant set temperatures imposed at the outer autoclave wall, whereas approximately quasi-stable conditions are reached about 3 h after reaching constant set temperatures. Short-term fluctuations in temperature are mostly due to fluctuations in velocity magnitude, usually with only minor variations in the flow direction. Full article
(This article belongs to the Special Issue Feature Papers in Electronic Materials Section (Volume 2)—15th Anniversary of Materials)
►▼ Show Figures

Figure 1

18 pages, 7017 KiB  
Article
Intercoupling of Cascaded Metasurfaces for Broadband Spectral Scalability
by Shaolin Zhou, Liang Liu, Qinling Deng, Shaowei Liao, Quan Xue and Mansun Chan
Materials 2023, 16(5), 2013; https://doi.org/10.3390/ma16052013 - 28 Feb 2023
Cited by 2 | Viewed by 1686
Abstract
Electromagnetic metasurfaces have been intensively used as ultra-compact and easy-to-integrate platforms for versatile wave manipulations from optical to terahertz (THz) and millimeter wave (MMW) ranges. In this paper, the less investigated effects of the interlayer coupling of multiple metasurfaces cascaded in parallel are [...] Read more.
Electromagnetic metasurfaces have been intensively used as ultra-compact and easy-to-integrate platforms for versatile wave manipulations from optical to terahertz (THz) and millimeter wave (MMW) ranges. In this paper, the less investigated effects of the interlayer coupling of multiple metasurfaces cascaded in parallel are intensively exploited and leveraged for scalable broadband spectral regulations. The hybridized resonant modes of cascaded metasurfaces with interlayer couplings are well interpreted and simply modeled by the transmission line lumped equivalent circuits, which are used in return to guide the design of the tunable spectral response. In particular, the interlayer gaps and other parameters of double or triple metasurfaces are deliberately leveraged to tune the inter-couplings for as-required spectral properties, i.e., the bandwidth scaling and central frequency shift. As a proof of concept, the scalable broadband transmissive spectra are demonstrated in the millimeter wave (MMW) range by cascading multilayers of metasurfaces sandwiched together in parallel with low-loss dielectrics (Rogers 3003). Finally, both the numerical and experimental results confirm the effectiveness of our cascaded model of multiple metasurfaces for broadband spectral tuning from a narrow band centered at 50 GHz to a broadened range of 40~55 GHz with ideal side steepness, respectively. Full article
(This article belongs to the Special Issue Quasi-Continuous Metasurfaces for High-Performance Functional Electromagnetic Wave Devices)
►▼ Show Figures

Figure 1

11 pages, 3887 KiB  
Article
Synthesis of Boron-Doped Carbon Nanomaterial
by Vladimir V. Chesnokov, Igor P. Prosvirin, Evgeny Yu. Gerasimov and Aleksandra S. Chichkan
Materials 2023, 16(5), 1986; https://doi.org/10.3390/ma16051986 - 28 Feb 2023
Cited by 3 | Viewed by 1882
Abstract
A new method for the synthesis of boron-doped carbon nanomaterial (B-carbon nanomaterial) has been developed. First, graphene was synthesized using the template method. Magnesium oxide was used as the template that was dissolved with hydrochloric acid after the graphene deposition on its surface. [...] Read more.
A new method for the synthesis of boron-doped carbon nanomaterial (B-carbon nanomaterial) has been developed. First, graphene was synthesized using the template method. Magnesium oxide was used as the template that was dissolved with hydrochloric acid after the graphene deposition on its surface. The specific surface area of the synthesized graphene was equal to 1300 m2/g. The suggested method includes the graphene synthesis via the template method, followed by the deposition of an additional graphene layer doped with boron in an autoclave at 650 °C, using a mixture of phenylboronic acid, acetone, and ethanol. After this carbonization procedure, the mass of the graphene sample increased by 70%. The properties of B-carbon nanomaterial were studied using X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and adsorption-desorption techniques. The deposition of an additional graphene layer doped with boron led to an increase of the graphene layer thickness from 2–4 to 3–8 monolayers, and a decrease of the specific surface area from 1300 to 800 m2/g. The boron concentration in B-carbon nanomaterial determined by different physical methods was about 4 wt.%. Full article
(This article belongs to the Special Issue Advanced Materials in Catalysis and Adsorption)
►▼ Show Figures

Figure 1

13 pages, 3897 KiB  
Article
Effect of a ZrO2 Seed Layer on an Hf0.5Zr0.5O2 Ferroelectric Device Fabricated via Plasma Enhanced Atomic Layer Deposition
by Ji-Na Song, Min-Jung Oh and Chang-Bun Yoon
Materials 2023, 16(5), 1959; https://doi.org/10.3390/ma16051959 - 27 Feb 2023
Cited by 2 | Viewed by 2030
Abstract
In this study, a ferroelectric layer was formed on a ferroelectric device via plasma enhanced atomic layer deposition. The device used 50 nm thick TiN as upper and lower electrodes, and an Hf0.5Zr0.5O2 (HZO) ferroelectric material was applied [...] Read more.
In this study, a ferroelectric layer was formed on a ferroelectric device via plasma enhanced atomic layer deposition. The device used 50 nm thick TiN as upper and lower electrodes, and an Hf0.5Zr0.5O2 (HZO) ferroelectric material was applied to fabricate a metal–ferroelectric–metal-type capacitor. HZO ferroelectric devices were fabricated in accordance with three principles to improve their ferroelectric properties. First, the HZO nanolaminate thickness of the ferroelectric layers was varied. Second, heat treatment was performed at 450, 550, and 650 °C to investigate the changes in the ferroelectric characteristics as a function of the heat-treatment temperature. Finally, ferroelectric thin films were formed with or without seed layers. Electrical characteristics such as the I–E characteristics, P–E hysteresis, and fatigue endurance were analyzed using a semiconductor parameter analyzer. The crystallinity, component ratio, and thickness of the nanolaminates of the ferroelectric thin film were analyzed via X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The residual polarization of the (20,20)*3 device heat treated at 550 °C was 23.94 μC/cm2, whereas that of the D(20,20)*3 device was 28.18 μC/cm2, which improved the characteristics. In addition, in the fatigue endurance test, the wake-up effect was observed in specimens with bottom and dual seed layers, which exhibited excellent durability after 108 cycles. Full article
(This article belongs to the Special Issue Preparation, Characterization and Application of Metal Oxide Thin Films)
►▼ Show Figures

Figure 1

9 pages, 11292 KiB  
Article
Epitaxial CdSe/PbSe Heterojunction Growth and MWIR Photovoltaic Detector
by Lance L. McDowell, Milad Rastkar Mirzaei and Zhisheng Shi
Materials 2023, 16(5), 1866; https://doi.org/10.3390/ma16051866 - 24 Feb 2023
Cited by 4 | Viewed by 1807
Abstract
A novel Epitaxial Cadmium Selenide (CdSe) on Lead Selenide (PbSe) type-II heterojunction photovoltaic detector has been demonstrated by Molecular Beam Epitaxy (MBE) growth of n-type CdSe on p-type PbSe single crystalline film. The use of Reflection High-Energy Electron Diffraction (RHEED) during the nucleation [...] Read more.
A novel Epitaxial Cadmium Selenide (CdSe) on Lead Selenide (PbSe) type-II heterojunction photovoltaic detector has been demonstrated by Molecular Beam Epitaxy (MBE) growth of n-type CdSe on p-type PbSe single crystalline film. The use of Reflection High-Energy Electron Diffraction (RHEED) during the nucleation and growth of CdSe indicates high-quality single-phase cubic CdSe. This is a first-time demonstration of single crystalline and single phase CdSe growth on single crystalline PbSe, to the best of our knowledge. The current–voltage characteristic indicates a p–n junction diode with a rectifying factor over 50 at room temperature. The detector structure is characterized by radiometric measurement. A 30 μm × 30 μm pixel achieved a peak responsivity of 0.06 A/W and a specific detectivity (D*) of 6.5 × 108 Jones under a zero bias photovoltaic operation. With decreasing temperature, the optical signal increased by almost an order of magnitude as it approached 230 K (with thermoelectric cooling) while maintaining a similar level of noise, achieving a responsivity of 0.441 A/W and a D* of 4.4 × 109 Jones at 230 K. Full article
(This article belongs to the Special Issue Epitaxial Growth of Semiconductor Materials)
►▼ Show Figures

Figure 1

16 pages, 2198 KiB  
Article
Properties and Emissions of Three-Layer Particleboards Manufactured with Mixtures of Wood Chips and Partially Liquefied Bark
by Wen Jiang, Stergios Adamopoulos, Reza Hosseinpourpia, Thomas Walther and Sergej Medved
Materials 2023, 16(5), 1855; https://doi.org/10.3390/ma16051855 - 24 Feb 2023
Cited by 3 | Viewed by 2984
Abstract
Partial liquefaction of residual biomass shows good potential for developing new materials suitable for making bio-based composites. Three-layer particleboards were produced by replacing virgin wood particles with partially liquefied bark (PLB) in the core or surface layers. PLB was prepared by the acid-catalyzed [...] Read more.
Partial liquefaction of residual biomass shows good potential for developing new materials suitable for making bio-based composites. Three-layer particleboards were produced by replacing virgin wood particles with partially liquefied bark (PLB) in the core or surface layers. PLB was prepared by the acid-catalyzed liquefaction of industrial bark residues in polyhydric alcohol. The chemical and microscopic structure of bark and residues after liquefaction were evaluated by means of Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), while the particleboards were tested for their mechanical and water-related properties, as well as their emission profiles. Through a partial liquefaction process, some FTIR absorption peaks of the bark residues were lower than those of raw bark, indicating hydrolysis of chemical compounds. The surface morphology of bark did not change considerably after partial liquefaction. Particleboards with PLB in the core layers showed overall lower densities and mechanical properties (modulus of elasticity, modulus of rupture, and internal bond strength), and were less water-resistant as compared to the ones with PLB used in the surface layers. Formaldehyde emissions from the particleboards were 0.284–0.382 mg/m2·h, and thus, below the E1 class limit required by European Standard EN 13986:2004. The major emissions of volatile organic compounds (VOCs) were carboxylic acids as oxidization and degradation products from hemicelluloses and lignin. The application of PLB in three-layer particleboards is more challenging than in single-layer boards as PLB has different effects on the core and surface layers. Full article
(This article belongs to the Special Issue Application of Natural Polymers in Bio-Based Products)
►▼ Show Figures

Figure 1

15 pages, 4694 KiB  
Article
Visual–Tactile Perception of Biobased Composites
by Manu Thundathil, Ali Reza Nazmi, Bahareh Shahri, Nick Emerson, Jörg Müssig and Tim Huber
Materials 2023, 16(5), 1844; https://doi.org/10.3390/ma16051844 - 23 Feb 2023
Cited by 2 | Viewed by 1747
Abstract
Biobased composites offer unique properties in the context of sustainable material production as well as end-of-life disposal, which places them as viable alternatives to fossil-fuel-based materials. However, the large-scale application of these materials in product design is hindered by their perceptual handicaps and [...] Read more.
Biobased composites offer unique properties in the context of sustainable material production as well as end-of-life disposal, which places them as viable alternatives to fossil-fuel-based materials. However, the large-scale application of these materials in product design is hindered by their perceptual handicaps and understanding the mechanism of biobased composite perception, and its constituents could pave the way to creating commercially successful biobased composites. This study examines the role of bimodal (visual and tactile) sensory evaluation in the formation of biobased composite perception through the Semantic Differential method. It is observed that the biobased composites could be grouped into different clusters based on the dominance and interplay of various senses in perception forming. Attributes such as Natural, Beautiful, and Valuable are seen to correlate with each other positively and are influenced by both visual and tactile characteristics of the biobased composites. Attributes such as Complex, Interesting, and Unusual are also positively correlated but dominated by visual stimuli. The perceptual relationships and components of beauty, naturality, and value and their constituent attributes are identified, along with the visual and tactile characteristics that influence these assessments. Material design leveraging these biobased composite characteristics could lead to the creation of sustainable materials that would be more attractive to designers and consumers. Full article
(This article belongs to the Special Issue Bio-Based Plastics and Biocomposite Materials)
►▼ Show Figures

Figure 1

13 pages, 2708 KiB  
Article
Electronic, Optical, Mechanical, and Electronic Transport Properties of SrCu2O2: A First-Principles Study
by Sheng Jiang, Chaohao Hu, Dianhui Wang, Yan Zhong and Chengying Tang
Materials 2023, 16(5), 1829; https://doi.org/10.3390/ma16051829 - 23 Feb 2023
Cited by 2 | Viewed by 1400
Abstract
The structural, electronic, optical, mechanical, lattice dynamics, and electronic transport properties of SrCu2O2 crystals were studied using first-principles calculations. The calculated band gap of SrCu2O2 using the HSE hybrid functional is about 3.33 eV, which is well [...] Read more.
The structural, electronic, optical, mechanical, lattice dynamics, and electronic transport properties of SrCu2O2 crystals were studied using first-principles calculations. The calculated band gap of SrCu2O2 using the HSE hybrid functional is about 3.33 eV, which is well consistent with the experimental value. The calculated optical parameters show a relatively strong response to the visible light region for SrCu2O2. The calculated elastic constants and phonon dispersion indicate that SrCu2O2 has strong stability in mechanical and lattice dynamics. The deep analysis of calculated mobilities of electrons and holes with their effective masses proves the high separation and low recombination efficiency of photoinduced carriers in SrCu2O2. Full article
(This article belongs to the Section Materials Simulation and Design)
►▼ Show Figures

Figure 1

12 pages, 2392 KiB  
Article
Optical Characterization of Thin Films by Surface Plasmon Resonance Spectroscopy Using an Acousto-Optic Tunable Filter
by Ildus Sh. Khasanov, Boris A. Knyazev, Sergey A. Lobastov, Alexander V. Anisimov, Pavel A. Nikitin and Oleg E. Kameshkov
Materials 2023, 16(5), 1820; https://doi.org/10.3390/ma16051820 - 22 Feb 2023
Cited by 4 | Viewed by 1674
Abstract
The paper presents the application of the acousto-optic tunable filter (AOTF) in surface plasmon resonance (SPR) spectroscopy to measure the optical thickness of thin dielectric coatings. The technique presented uses combined angular and spectral interrogation modes to obtain the reflection coefficient under the [...] Read more.
The paper presents the application of the acousto-optic tunable filter (AOTF) in surface plasmon resonance (SPR) spectroscopy to measure the optical thickness of thin dielectric coatings. The technique presented uses combined angular and spectral interrogation modes to obtain the reflection coefficient under the condition of SPR. Surface electromagnetic waves were excited in the Kretschmann geometry, with the AOTF serving as a monochromator and polarizer of light from a white broadband radiation source. The experiments highlighted the high sensitivity of the method and the lower amount of noise in the resonance curves compared with the laser light source. This optical technique can be implemented for nondestructive testing in the production of thin films in not only the visible, but also the infrared and terahertz ranges. Full article
(This article belongs to the Special Issue Acousto-Optical Spectral Technologies)
►▼ Show Figures

Graphical abstract

12 pages, 3628 KiB  
Article
Fluorinated Multi-Walled Carbon Nanotubes Coated Separator Mitigates Polysulfide Shuttle in Lithium-Sulfur Batteries
by Devashish Salpekar, Changxin Dong, Eliezer F. Oliveira, Valery N. Khabashesku, Guanhui Gao, Ved Ojha, Robert Vajtai, Douglas S. Galvao, Ganguli Babu and Pulickel M. Ajayan
Materials 2023, 16(5), 1804; https://doi.org/10.3390/ma16051804 - 22 Feb 2023
Cited by 1 | Viewed by 1972
Abstract
Li-S batteries still suffer from two of the major challenges: polysulfide shuttle and low inherent conductivity of sulfur. Here, we report a facile way to develop a bifunctional separator coated with fluorinated multiwalled carbon nanotubes. Mild fluorination does not affect the inherent graphitic [...] Read more.
Li-S batteries still suffer from two of the major challenges: polysulfide shuttle and low inherent conductivity of sulfur. Here, we report a facile way to develop a bifunctional separator coated with fluorinated multiwalled carbon nanotubes. Mild fluorination does not affect the inherent graphitic structure of carbon nanotubes as shown by transmission electron microscopy. Fluorinated carbon nanotubes show an improved capacity retention by trapping/repelling lithium polysulfides at the cathode, while simultaneously acting as the “second current collector”. Moreover, reduced charge-transfer resistance and enhanced electrochemical performance at the cathode-separator interface result in a high gravimetric capacity of around 670 mAh g−1 at 4C. Unique chemical interactions between fluorine and carbon at the separator and the polysulfides, studied using DFT calculations, establish a new direction of utilizing highly electronegative fluorine moieties and absorption-based porous carbons for mitigation of polysulfide shuttle in Li-S batteries. Full article
(This article belongs to the Special Issue Recent Advances in Functional Nanomaterials)
►▼ Show Figures

Figure 1

13 pages, 3358 KiB  
Article
Enhanced Luminescence of Yb3+ Ions Implanted to ZnO through the Selection of Optimal Implantation and Annealing Conditions
by Renata Ratajczak, Elzbieta Guziewicz, Slawomir Prucnal, Cyprian Mieszczynski, Przemysław Jozwik, Marek Barlak, Svitlana Romaniuk, Sylwia Gieraltowska, Wojciech Wozniak, René Heller, Ulrich Kentsch and Stefan Facsko
Materials 2023, 16(5), 1756; https://doi.org/10.3390/ma16051756 - 21 Feb 2023
Cited by 2 | Viewed by 1742
Abstract
Rare earth-doped zinc oxide (ZnO:RE) systems are attractive for future optoelectronic devices such as phosphors, displays, and LEDs with emission in the visible spectral range, working even in a radiation-intense environment. The technology of these systems is currently under development, opening up new [...] Read more.
Rare earth-doped zinc oxide (ZnO:RE) systems are attractive for future optoelectronic devices such as phosphors, displays, and LEDs with emission in the visible spectral range, working even in a radiation-intense environment. The technology of these systems is currently under development, opening up new fields of application due to the low-cost production. Ion implantation is a very promising technique to incorporate rare-earth dopants into ZnO. However, the ballistic nature of this process makes the use of annealing essential. The selection of implantation parameters, as well as post-implantation annealing, turns out to be non-trivial because they determine the luminous efficiency of the ZnO:RE system. This paper presents a comprehensive study of the optimal implantation and annealing conditions, ensuring the most efficient luminescence of RE3+ ions in the ZnO matrix. Deep and shallow implantations, implantations performed at high and room temperature with various fluencies, as well as a range of post-RT implantation annealing processes are tested: rapid thermal annealing (minute duration) under different temperatures, times, and atmospheres (O2, N2, and Ar), flash lamp annealing (millisecond duration) and pulse plasma annealing (microsecond duration). It is shown that the highest luminescence efficiency of RE3+ is obtained for the shallow implantation at RT with the optimal fluence of 1.0 × 1015 RE ions/cm2 followed by a 10 min annealing in oxygen at 800 °C, and the light emission from such a ZnO:RE system is so bright that can be observed with the naked eye. Full article
(This article belongs to the Section Optical and Photonic Materials)
►▼ Show Figures

Graphical abstract

15 pages, 7293 KiB  
Article
Electrochemical Impedance Spectroscopy (EIS) Explanation of Single Crystal Cu(100)/Cu(111) in Different Corrosion Stages
by Qihao Lin, Guoqing Chen, Shiwen Zou, Wenlong Zhou, Xuesong Fu and Shuyan Shi
Materials 2023, 16(4), 1740; https://doi.org/10.3390/ma16041740 - 20 Feb 2023
Cited by 3 | Viewed by 2346
Abstract
Copper and its alloys are used widely in marine environments, and anisotropic corrosion influences the corrosion kinetics of copper. Corrosion of copper in an electrolyte containing Cl− is described as a dissolution–deposition process, which is a prolonged process. Therefore, it is laborious [...] Read more.
Copper and its alloys are used widely in marine environments, and anisotropic corrosion influences the corrosion kinetics of copper. Corrosion of copper in an electrolyte containing Cl− is described as a dissolution–deposition process, which is a prolonged process. Therefore, it is laborious to clarify the corrosion anisotropy in different stages. In this paper, electrochemical impedance spectroscopy (EIS) following elapsed open circuit potential (OCP) test with 0 h (0H), 24 h (24H) and 10 days (10D) was adopted. To exclude interruptions such as grain boundary and neighbor effect, single crystal (SC) Cu(100) and Cu(111) were employed. After 10D OCP, cross-sectional slices were cut and picked up by a focused ion beam (FIB). The results showed that the deposited oxide was Cu2O and Cu(100)/Cu(111) experienced different corrosion behaviors. In general, Cu(100) showed more excellent corrosion resistance. Combined with equivalent electrical circuit (EEC) diagrams, the corrosion mechanism of Cu(100)/Cu(111) in different stages was proposed. In the initial stage, a smaller capacitive loop of Cu(111) suggested preferential adsorption of Cl− on air-formed oxide film on Cu(111). Deposited oxide and exposed bare metals also played an important role in corrosion resistance. Rectangle indentations and pyramidal structures formed on Cu(100)/Cu(111), respectively. Finally, a perfect interface on Cu(100) explained the tremendous capacitive loop and higher impedance (14,274 Ω·cm2). Moreover, defects in the oxides on Cu(111) provided channels for the penetration of electrolyte, leading to a lower impedance (9423 Ω·cm2) after 10D corrosion. Full article
(This article belongs to the Special Issue Advance in Corrosion and Protection of Metals)
►▼ Show Figures

Figure 1

24 pages, 21486 KiB  
Article
Characterization of Ruddlesden-Popper La2−xBaxNiO4±δ Nickelates as Potential Electrocatalysts for Solid Oxide Cells
by Kiryl Zakharchuk, Andrei Kovalevsky and Aleksey Yaremchenko
Materials 2023, 16(4), 1755; https://doi.org/10.3390/ma16041755 - 20 Feb 2023
Cited by 7 | Viewed by 2139
Abstract
Ruddlesden-Popper La2−xBaxNiO4±δ (x = 0–1.1) nickelates were prepared by a glycine-nitrate combustion route combined with high-temperature processing and evaluated for potential application as electrocatalysts for solid oxide cells and electrochemical NOx elimination. The characterization included [...] Read more.
Ruddlesden-Popper La2−xBaxNiO4±δ (x = 0–1.1) nickelates were prepared by a glycine-nitrate combustion route combined with high-temperature processing and evaluated for potential application as electrocatalysts for solid oxide cells and electrochemical NOx elimination. The characterization included structural, microstructural and dilatometric studies, determination of oxygen nonstoichiometry, measurements of electrical conductivity and oxygen permeability, and assessment of chemical compatibility with other materials. The formation range of phase-pure solid solutions was found to be limited to x = 0.5. Exceeding this limit leads to the co-existence of the main nickelate phase with low-melting Ba- and Ni-based secondary phases responsible for a strong reactivity with Pt components in experimental cells. Acceptor-type substitution of lanthanum by barium in La2−xBaxNiO4+δ is charge-compensated by decreasing oxygen excess, from δ ≈ 0.1 for x = 0 to nearly oxygen-stoichiometric state for x = 0.5 at 800 °C in air, and generation of electron-holes (formation of Ni3+). This leads to an increase in p-type electronic conductivity (up to ~80 S/cm for highly porous La1.5Ba0.5NiO4+δ ceramics at 450–900 °C) and a decline of oxygen-ionic transport. La2−xBaxNiO4+δ (x = 0–0.5) ceramics exhibit moderate thermal expansion coefficients, 13.8–14.3 ppm/K at 25–1000 °C in air. These ceramic materials react with yttria-stabilized zirconia at 700 °C with the formation of an insulating La2Zr2O7 phase but show good chemical compatibility with BaZr0.85Y0.15O3−δ solid electrolyte. Full article
(This article belongs to the Section Materials Chemistry)
►▼ Show Figures

Figure 1

16 pages, 4668 KiB  
Article
Expanded Glass for Thermal and Acoustic Insulation from Recycled Post-Consumer Glass and Textile Industry Process Waste
by Luca Cozzarini, Lorenzo De Lorenzi, Nicolò Barago, Orfeo Sbaizero and Paolo Bevilacqua
Materials 2023, 16(4), 1721; https://doi.org/10.3390/ma16041721 - 19 Feb 2023
Cited by 4 | Viewed by 1734
Abstract
The production of glass foams obtained by recycling post-consumer glass and textile industry processing waste is presented. The mechanical, thermal and acoustic properties were characterized as a function of process temperature and time. The results showed that it is possible to produce glass [...] Read more.
The production of glass foams obtained by recycling post-consumer glass and textile industry processing waste is presented. The mechanical, thermal and acoustic properties were characterized as a function of process temperature and time. The results showed that it is possible to produce glass foams with thermal and acoustic insulation properties from a mixture consisting of 96.5% of glass waste, 1% of textile waste and 2.5% of manganese dioxide, processed at temperatures between 800 and 900 °C for a time between 30 and 90 min. The samples had density in the range of 200–300 kg m−3, porosity of 87–92%, thermal conductivity of 85–105 mW m−1 K−1, noise-reducing factors of 0.15–0.40 and compressive strength of 1.2–3.0 MPa. Although their insulation performance was not as outstanding as that of polymer foams, these materials can emerge as competitive candidates for applications requiring non-flammability and high-temperature load bearing capacity in combination with low weight, mechanical strength, and thermal and acoustic insulation properties. The use of secondary raw materials (which accounted for 97.5% by weight of the synthetic blend) limits the energy required compared to that needed for the extraction, transportation and processing of primary raw materials, making these foams attractive also in terms of environmental footprint. Full article
(This article belongs to the Section Advanced and Functional Ceramics and Glasses)
►▼ Show Figures

Figure 1

14 pages, 3665 KiB  
Article
Changes in Abrasion Resistance of Cast Cr-Ni Steel as a Result of the Formation of Niobium Carbides in Alloy Matrix
by Grzegorz Tęcza
Materials 2023, 16(4), 1726; https://doi.org/10.3390/ma16041726 - 19 Feb 2023
Cited by 2 | Viewed by 1557
Abstract
Cast austenitic chromium-nickel steel is commonly used for the manufacture of machine parts and components, which are exposed to the attack of corrosive media and abrasive wear during operation. The most commonly used grades include GX2CrNi18-9 and X10CrNi18-8 as well as GX2CrNiMo17-12-2 and [...] Read more.
Cast austenitic chromium-nickel steel is commonly used for the manufacture of machine parts and components, which are exposed to the attack of corrosive media and abrasive wear during operation. The most commonly used grades include GX2CrNi18-9 and X10CrNi18-8 as well as GX2CrNiMo17-12-2 and X6CrNiMoNb17-12-2. To improve the abrasion resistance of cast chromium-nickel steel, primary niobium carbides were produced in the metallurgical process by increasing the carbon content and adding Fe-Nb. The microstructure of the obtained test castings consisted of an austenitic matrix and primary niobium carbides evenly distributed in this matrix. The measured hardness of the samples after heat treatment ranged from 215 to 240 HV and was higher by about 60 units than the hardness of the reference cast GX10CrNi18-9 steel, which had a hardness of about 180 HV. Compared to the reference cast steel, the abrasive wear resistance of the tested cast chromium-nickel steel (measured in Miller test) with contents of 4.4 and 5.4 wt% Nb increased only slightly, i.e., by 5% for the lower niobium content and 11% for the higher niobium content. Compared to ordinary cast GX10CrNi18-9 steel, the addition of 9.2 wt% Nb reduced the abrasive wear by almost 2.5 times. Full article
(This article belongs to the Special Issue Advances in Alloys - Microstructure, Manufacturing and Analysis)
►▼ Show Figures

Figure 1

14 pages, 3491 KiB  
Article
Strong and Flexible Braiding Pattern of Carbon Nanotubes for Composites: Stiff and Robust Structure Active in Composite Materials
by Fumio Ogawa, Fan Liu and Toshiyuki Hashida
Materials 2023, 16(4), 1725; https://doi.org/10.3390/ma16041725 - 19 Feb 2023
Cited by 1 | Viewed by 1650
Abstract
Carbon nanotubes (CNTs) exhibit high strength, Young’s modulus, and flexibility and serve as an ideal reinforcement for composite materials. Owing to their toughness against bending and/or twisting, they are typically used as fabric composites. The conventional multiaxial braiding method lacks tension and resultant [...] Read more.
Carbon nanotubes (CNTs) exhibit high strength, Young’s modulus, and flexibility and serve as an ideal reinforcement for composite materials. Owing to their toughness against bending and/or twisting, they are typically used as fabric composites. The conventional multiaxial braiding method lacks tension and resultant strength in the thickness direction. Some braiding patterns are proposed; however, they may have shortcomings in flexibility. Thus, this study proposed three types of braiding pattern for fabrics based on natural products such as spider net and honeycomb, in accordance with thickness-direction strength. The spider-net-based structure included wefts with spaces in the center with overlapping warps. At both sides, the warps crossed and contacted the wefts to impart solidness to the structure and enhance its strength as well as flexural stability. In addition, box-type wefts were proposed by unifying the weft and warps into boxes, which enhanced the stability and flexibility of the framework. Finally, we proposed a structure based on rectangular and hexagonal shapes mimicking the honeycomb. Moreover, finite element calculations were performed to investigate the mechanisms through which the proposed structures garnered strength and deformation ability. The average stress in fabrics becomes smaller than half (43%) when four edges are restrained and sliding is inserted. Under three-dimensional forces, our proposed structures underwent mechanisms of wrapping, warping, sliding and doubling, and partial locking to demonstrate their enhanced mechanical properties. Furthermore, we proposed a hierarchical structure specialized for CNTs, which could facilitate applications in structural components of satellites, wind turbines, and ships. The hierarchical structure utilizing discontinuity and sliding benefits the usage for practical mechanical systems. Full article
(This article belongs to the Special Issue Advanced Textile Materials: Design, Properties and Applications)
►▼ Show Figures

Figure 1

9 pages, 2538 KiB  
Article
Analog Resistive Switching and Artificial Synaptic Behavior of ITO/WOX/TaN Memristors
by Youngboo Cho, Jihyung Kim, Myounggon Kang and Sungjun Kim
Materials 2023, 16(4), 1687; https://doi.org/10.3390/ma16041687 - 17 Feb 2023
Cited by 5 | Viewed by 1554
Abstract
In this work, we fabricated an ITO/WOX/TaN memristor device by reactive sputtering to investigate resistive switching and conduct analog resistive switching to implement artificial synaptic devices. The device showed good pulse endurance (104 cycles), a high on/off ratio (>10), and [...] Read more.
In this work, we fabricated an ITO/WOX/TaN memristor device by reactive sputtering to investigate resistive switching and conduct analog resistive switching to implement artificial synaptic devices. The device showed good pulse endurance (104 cycles), a high on/off ratio (>10), and long retention (>104 s) at room temperature. The conduction mechanism could be explained by Schottky emission conduction. Further, the resistive switching characteristics were performed by additional pulse-signal-based experiments for more practical operation. Lastly, the potentiation/depression characteristics were examined for 10 cycles. The results thus indicate that the WOX-based devices are appropriate candidates for synaptic devices as well as next-generation nonvolatile memory. Full article
(This article belongs to the Special Issue Prospects of Oxide Materials Electronic Structure and Related Applications in Devices)
►▼ Show Figures

Figure 1

18 pages, 8566 KiB  
Article
Hydrothermal Synthesis of ZnO Superstructures with Controlled Morphology via Temperature and pH Optimization
by Aleksander Ejsmont and Joanna Goscianska
Materials 2023, 16(4), 1641; https://doi.org/10.3390/ma16041641 - 16 Feb 2023
Cited by 10 | Viewed by 3149
Abstract
Zinc oxide, as a widely used material in optics, electronics, and medicine, requires a complete overview of different conditions for facile and easily reproducible syntheses. Two types of optimization of ZnO hydrothermal preparation from zinc acetate and sodium hydroxide solution are presented, which [...] Read more.
Zinc oxide, as a widely used material in optics, electronics, and medicine, requires a complete overview of different conditions for facile and easily reproducible syntheses. Two types of optimization of ZnO hydrothermal preparation from zinc acetate and sodium hydroxide solution are presented, which allowed for obtaining miscellaneous morphologies of materials. The first was a temperature-controlled synthesis from 100 to 200 °C, using citric acid as a capping agent. The formation of hexagonal rods at the lowest temperature was evidenced, which agglomerated to flower-like structures at 110 and 120 °C. It was followed by transformation to flake-like roses at 160 °C, up to disordered structures composed of nanosized plates (>180 °C). The transformations were generated through a temperature change, which had an impact on the diffusion effect of hydroxide and citrate complexes. The second optimization was the hydrothermal synthesis free of organic additives and it included only a pH variation from 7.5 to 13.5. It was found that by utilizing a slow-dropping process and varying amounts of NaOH solutions, it is possible to obtain well-formed hexagonal pellets at pH 8.0–8.5. Strongly basic conditions of pH 11.0 and 13.5 impeded superstructure formations, giving small elongated particles of ZnO. All samples were characterized by high phase purity and crystallinity, with a specific surface area of 18–37 m2/g, whereas particle size distribution indicated a predominance of small particles (<1 μm). Full article
(This article belongs to the Section Materials Chemistry)
►▼ Show Figures

Graphical abstract

11 pages, 4308 KiB  
Article
Correlation-Driven Topological Transition in Janus Two-Dimensional Vanadates
by Ghulam Hussain, Amar Fakhredine, Rajibul Islam, Raghottam M. Sattigeri, Carmine Autieri and Giuseppe Cuono
Materials 2023, 16(4), 1649; https://doi.org/10.3390/ma16041649 - 16 Feb 2023
Cited by 6 | Viewed by 1805
Abstract
The appearance of intrinsic ferromagnetism in 2D materials opens the possibility of investigating the interplay between magnetism and topology. The magnetic anisotropy energy (MAE) describing the easy axis for magnetization in a particular direction is an important yardstick for nanoscale applications. Here, the [...] Read more.
The appearance of intrinsic ferromagnetism in 2D materials opens the possibility of investigating the interplay between magnetism and topology. The magnetic anisotropy energy (MAE) describing the easy axis for magnetization in a particular direction is an important yardstick for nanoscale applications. Here, the first-principles approach is used to investigate the electronic band structures, the strain dependence of MAE in pristine VSi2Z4 (Z = P, As) and its Janus phase VSiGeP2As2 and the evolution of the topology as a function of the Coulomb interaction. In the Janus phase the compound presents a breaking of the mirror symmetry, which is equivalent to having an electric field, and the system can be piezoelectric. It is revealed that all three monolayers exhibit ferromagnetic ground state ordering, which is robust even under biaxial strains. A large value of coupling J is obtained, and this, together with the magnetocrystalline anisotropy, will produce a large critical temperature. We found an out-of-plane (in-plane) magnetization for VSi2P4 (VSi2As4), and an in-plane magnetization for VSiGeP2As2. Furthermore, we observed a correlation-driven topological transition in the Janus VSiGeP2As2. Our analysis of these emerging pristine and Janus-phased magnetic semiconductors opens prospects for studying the interplay between magnetism and topology in two-dimensional materials. Full article
(This article belongs to the Special Issue Advances in Magnetoelectric Multiferroic Materials and Heterostructures: Properties, Techniques and Devises)
►▼ Show Figures

Figure 1

15 pages, 5714 KiB  
Article
Guard Ring Design to Prevent Edge Breakdown in Double-Diffused Planar InGaAs/InP Avalanche Photodiodes
by Yu-Chun Chen, Ruei-Hong Yan, Hsu-Chia Huang, Liang-Hsuan Nieh and Hao-Hsiung Lin
Materials 2023, 16(4), 1667; https://doi.org/10.3390/ma16041667 - 16 Feb 2023
Viewed by 2291
Abstract
We report on the design of an attached guard ring (AGR) and a floating guard ring (FGR) in a planar separate absorption, grading, charge, and multiplication In0.53Ga0.47As/InP avalanche photodiode to prevent premature edge breakdowns. The depths of the two [...] Read more.
We report on the design of an attached guard ring (AGR) and a floating guard ring (FGR) in a planar separate absorption, grading, charge, and multiplication In0.53Ga0.47As/InP avalanche photodiode to prevent premature edge breakdowns. The depths of the two Zn diffusions were utilized to manipulate the guard ring structures. Results from TCAD simulation indicate that the optimal AGR diffusion depth is right at the turning point where the breakdown current shifts from the edge of active region to the AGR region. The devices with optimal AGR depth contain significantly higher breakdown voltages than those of devices either with shallower—or without any— AGR. For the FGR design, a series of devices with different spacings between AGR and FGR and different FGR opening widths for diffusion were fabricated and characterized. We show that when the spacing is longer than the critical value, the breakdown voltage can increase ~1.5 V higher than those of the APD devices without FGR. In addition, the wider the FGR opening width, the higher the breakdown voltage. TCAD simulations were also performed to study the effect of FGR, but showed less pronounced improvements, which could be due the discrepancy between the calculated and experimental diffusion profile. Full article
(This article belongs to the Special Issue Opto/Electronics Materials and Devices Applied for Telecommunications)
►▼ Show Figures

Figure 1

12 pages, 3917 KiB  
Article
An Ultra-Broadband and Highly-Efficient Metamaterial Absorber with Stand-Up Gradient Impedance Graphene Films
by Bian Wu, Biao Chen, Shuai Ma, Ding Zhang and Hao-Ran Zu
Materials 2023, 16(4), 1617; https://doi.org/10.3390/ma16041617 - 15 Feb 2023
Cited by 1 | Viewed by 1446
Abstract
Metamaterial absorbers (MMAs) that absorb electromagnetic waves among an ultra-broad frequency band have attracted great attention in military and civilian applications. In this paper, an ultra-broadband and highly-efficient MMA is presented. The unit cell of the proposed MMA was constructed with two cross-placed [...] Read more.
Metamaterial absorbers (MMAs) that absorb electromagnetic waves among an ultra-broad frequency band have attracted great attention in military and civilian applications. In this paper, an ultra-broadband and highly-efficient MMA is presented. The unit cell of the proposed MMA was constructed with two cross-placed stand-up gradient impedance graphene films, which play a key role in improving impedance matching. Considering the trade-off between absorbing performance and processing complexity, in our design, we adopted the stand-up graphene films that have a gradient with three orders of magnitude in total. The simulated results of the proposed absorber show an ultra-broadband absorption (absorptivity > 90%) from 1.8 GHz to 66.7 GHz and a highly-efficient absorption (absorptivity > 97%) in the range of 2–21.7 GHz and 39.6–57 GHz. The field analysis was adopted to explain the mechanism of the proposed absorber. To validate this design, a prototype of 20 × 20 units was processed and assembled. The graphene films were processed with graphene conductive ink using screen print technology. The measured results are in good agreement with the simulated ones. The proposed absorber may find potential applications in the field of stealth technologies and electromagnetic interference. Full article
(This article belongs to the Special Issue Application of Graphene-Based Materials in Sensors and RF Electronics)
►▼ Show Figures

Figure 1

14 pages, 7008 KiB  
Article
Silver Nanoparticles for Fluorescent Nanocomposites by High-Pressure Magnetron Sputtering
by Tomáš Zikmund, Jiří Bulíř, Michal Novotný, Ladislav Fekete, Sergii Chertopalov, Stefan Andrei Irimiciuc, Mariana Klementová, Jarmila Balogová and Jan Lančok
Materials 2023, 16(4), 1591; https://doi.org/10.3390/ma16041591 - 14 Feb 2023
Cited by 3 | Viewed by 1556
Abstract
We report on the formation of silver nanoparticles by gas aggregation in a reaction chamber at room temperature. The size distribution of nanoparticles deposited on a silicon substrate for various lengths of an aggregation (high-pressure) chamber was investigated by atomic force microscopy. Nanoparticles [...] Read more.
We report on the formation of silver nanoparticles by gas aggregation in a reaction chamber at room temperature. The size distribution of nanoparticles deposited on a silicon substrate for various lengths of an aggregation (high-pressure) chamber was investigated by atomic force microscopy. Nanoparticles were characterized by scanning and transmission electron microscopy and spectral ellipsometry. The physical shape of the nanoparticles and its distribution was correlated with their optical properties. Metal–dielectric nanocomposites were deposited employing simultaneous deposition of Ag NPs via high-pressure magnetron sputtering and the dielectric matrix was deposited via thermal evaporation. Pure and Eu-, Er-, and Yb-doped lithium fluoride was used as the dielectric host matrix. Optical transmittance of lithium fluoride containing silver nanoparticles was measured and their theoretical absorption cross-section calculated. The nanoparticles were also embedded in Eu3+-doped downshifting and Er3+- and Yb3+-doped up-conversion materials to study their influence on emission spectra. Spectra of identical layers with and without nanoparticles were compared. Their transmittance at various annealing temperatures is also presented. Full article
(This article belongs to the Special Issue Structural, Morphological, and Optical Properties of Functional Thin Films)
►▼ Show Figures

Figure 1

10 pages, 2714 KiB  
Article
Graphene/PVDF Nanocomposite-Based Accelerometer for Detection of Low Vibrations
by Surendra Maharjan, Victor K. Samoei and Ahalapitiya H. Jayatissa
Materials 2023, 16(4), 1586; https://doi.org/10.3390/ma16041586 - 14 Feb 2023
Cited by 3 | Viewed by 1884
Abstract
A flexible piezoresistive sensor was developed as an accelerometer based on Graphene/PVDF nanocomposite to detect low-frequency and low amplitude vibration of industrial machines, which may be caused due to misalignment, looseness of fasteners, or eccentric rotation. The sensor was structured as a cantilever [...] Read more.
A flexible piezoresistive sensor was developed as an accelerometer based on Graphene/PVDF nanocomposite to detect low-frequency and low amplitude vibration of industrial machines, which may be caused due to misalignment, looseness of fasteners, or eccentric rotation. The sensor was structured as a cantilever beam with the proof mass at the free end. The vibration caused the proof mass to accelerate up and down, which was converted into an electrical signal. The output was recorded as the change in resistance (response percentage) with respect to the acceleration. It was found that this accelerometer has a capability of detecting acceleration up to 8 gpk-pk in the frequency range of 20 Hz to 80 Hz. The developed accelerometer has the potential to represent an alternative to the existing accelerometers due to its compactness, simplicity, and higher sensitivity for low frequency and low amplitude applications. Full article
(This article belongs to the Special Issue Low-Dimensional Structures for Smart Materials and Composites: Preparation, Properties and Applications)
►▼ Show Figures

Figure 1

19 pages, 9066 KiB  
Article
Epoxy and Bio-Based Epoxy Carbon Fiber Twill Composites: Comparison of the Quasi-Static Properties
by Carlo Boursier Niutta, Raffaele Ciardiello, Andrea Tridello and Davide S. Paolino
Materials 2023, 16(4), 1601; https://doi.org/10.3390/ma16041601 - 14 Feb 2023
Cited by 6 | Viewed by 1444
Abstract
In recent years, interest in sustainability has significantly increased in many industrial sectors. Sustainability can be achieved with both lightweight design and eco-friendly manufacturing processes. For example, concerns on the use of thermoset composite materials, with a lightweight design and a high specific [...] Read more.
In recent years, interest in sustainability has significantly increased in many industrial sectors. Sustainability can be achieved with both lightweight design and eco-friendly manufacturing processes. For example, concerns on the use of thermoset composite materials, with a lightweight design and a high specific strength, have arisen, since thermoset resins are not fully recyclable and are mainly petrol based. A possible solution to this issue is the replacement of the thermoset matrix with a recyclable or renewable matrix, such as bio-based resin. However, the mechanical properties of composites made with bio-based resin should be carefully experimentally assessed to guarantee a safe design and the structural integrity of the components. In this work, the quasi-static mechanical properties of composite specimens (eight layers of carbon fiber fabric) made with commercially available epoxy and a bio-based epoxy resins (31% bio content) are compared. Tensile tests on the investigated resins and tensile, compression, shear and flexural tests have been carried out on composite laminates manufactured with the two investigated resins. A finite element model has been calibrated in the LS-Dyna environment using the experimentally assessed mechanical properties. The experimental results have proven that the two composites showed similar quasi-static properties, proving that bio-based composite materials can be reliably employed as a substitute for epoxy resins without affecting the structural integrity of the component but lowering their carbon footprint. Full article
(This article belongs to the Special Issue Recent Advances in Biobased and Biodegradable Polymers)
►▼ Show Figures

Figure 1

18 pages, 9058 KiB  
Review
The Historical Development of Infrared Photodetection Based on Intraband Transitions
by Qun Hao, Xue Zhao, Xin Tang and Menglu Chen
Materials 2023, 16(4), 1562; https://doi.org/10.3390/ma16041562 - 13 Feb 2023
Cited by 4 | Viewed by 2447
Abstract
The infrared technology is entering widespread use as it starts fulfilling a growing number of emerging applications, such as smart buildings and automotive sectors. Majority of infrared photodetectors are based on interband transition, which is the energy gap between the valence band and [...] Read more.
The infrared technology is entering widespread use as it starts fulfilling a growing number of emerging applications, such as smart buildings and automotive sectors. Majority of infrared photodetectors are based on interband transition, which is the energy gap between the valence band and the conduction band. As a result, infrared materials are mainly limited to semi-metal or ternary alloys with narrow-bandgap bulk semiconductors, whose fabrication is complex and expensive. Different from interband transition, intraband transition utilizing the energy gap inside the band allows for a wider choice of materials. In this paper, we mainly discuss the recent developments on intraband infrared photodetectors, including ‘bottom to up’ devices such as quantum well devices based on the molecular beam epitaxial approach, as well as ‘up to bottom’ devices such as colloidal quantum dot devices based on the chemical synthesis. Full article
(This article belongs to the Section Quantum Materials)
►▼ Show Figures

Figure 1

12 pages, 4312 KiB  
Article
Single Crystals of EuScCuSe3: Synthesis, Experimental and DFT Investigations
by Maxim V. Grigoriev, Anna V. Ruseikina, Vladimir A. Chernyshev, Aleksandr S. Oreshonkov, Alexander A. Garmonov, Maxim S. Molokeev, Ralf J. C. Locke, Andrey V. Elyshev and Thomas Schleid
Materials 2023, 16(4), 1555; https://doi.org/10.3390/ma16041555 - 13 Feb 2023
Cited by 1 | Viewed by 1535
Abstract
EuScCuSe3 was synthesized from the elements for the first time by the method of cesium-iodide flux. The crystal belongs to the orthorhombic system (Cmcm) with the unit cell parameters a = 3.9883(3) Å, b = 13.2776(9) Å, c = 10.1728(7) [...] Read more.
EuScCuSe3 was synthesized from the elements for the first time by the method of cesium-iodide flux. The crystal belongs to the orthorhombic system (Cmcm) with the unit cell parameters a = 3.9883(3) Å, b = 13.2776(9) Å, c = 10.1728(7) Å, V = 538.70(7) Å3. Density functional (DFT) methods were used to study the crystal structure stability of EuScCuSe3 in the experimentally obtained Cmcm and the previously proposed Pnma space groups. It was shown that analysis of elastic properties as Raman and infrared spectroscopy are powerless for this particular task. The instability of EuScCuSe3 in space group Pnma space group is shown on the basis of phonon dispersion curve simulation. The EuScCuSe3 can be assigned to indirect wide-band gap semiconductors. It exhibits the properties of a soft ferromagnet at temperatures below 2 K. Full article
(This article belongs to the Special Issue Advances in Density Functional Theory (DFT) Studies of Solids (Second Volume))
►▼ Show Figures

Figure 1

8 pages, 3445 KiB  
Article
Effect of Surface Dispersion of Fe Nanoparticles on the Room-Temperature Flash Sintering Behavior of 3YSZ
by Angxuan Wu, Yuchen Zhu, Chen Xu, Nianping Yan, Xuetong Zhao, Xilin Wang and Zhidong Jia
Materials 2023, 16(4), 1544; https://doi.org/10.3390/ma16041544 - 13 Feb 2023
Cited by 2 | Viewed by 1427
Abstract
Arc floating in surface flashover can be controlled by reducing the interfacial charge-transfer resistance of ceramics. However, thus far, only a few studies have been conducted on methods of treating ceramic surfaces directly to reduce the interfacial charge-transfer resistance. Herein, we explore the [...] Read more.
Arc floating in surface flashover can be controlled by reducing the interfacial charge-transfer resistance of ceramics. However, thus far, only a few studies have been conducted on methods of treating ceramic surfaces directly to reduce the interfacial charge-transfer resistance. Herein, we explore the flash sintering behavior of a ceramic surface (3 mol% yttria-stabilized zirconia (3YSZ)) onto which loose metal (iron) powder was spread prior to flash sintering at room temperature (25 °C). The iron powder acts as a conductive phase that accelerates the start of flash sintering while also doping the ceramic phase during the sintering process. Notably, the iron powder substantially reduces the transition time from the arc stage to the flash stage from 13.50 to 8.22 s. The surface temperature (~1600 °C) of the ceramic substrate is sufficiently high to melt the iron powder. The molten metal then reacts with the ceramic surface, causing iron ions to substitute Zr4+ ions and promoting rapid densification. The YSZ grains in the metal-infiltrated area grow exceptionally fast. The results demonstrate that spreading metal powder onto a ceramic surface prior to flash sintering can enable the metal to enter the ceramic pores, which will be of significance in developing and enhancing ceramic–metal powder processing techniques. Full article
(This article belongs to the Special Issue Advanced Ceramics and Composites: Design, Structure, Processing, Properties, and Applications)
►▼ Show Figures

Figure 1

17 pages, 12522 KiB  
Article
Porous Thermoplastic Molded Regenerated Silk Crosslinked by the Addition of Citric Acid
by Alessio Bucciarelli, Nicola Vighi, Alessandra Maria Bossi, Brunella Grigolo and Devid Maniglio
Materials 2023, 16(4), 1535; https://doi.org/10.3390/ma16041535 - 12 Feb 2023
Viewed by 1750
Abstract
Thermoplastic molded regenerated silk fibroin was proposed as a structural material in tissue engineering applications, mainly for application in bone. The protocol allows us to obtain a compact non-porous material with a compression modulus in the order of a Giga Pascal in dry [...] Read more.
Thermoplastic molded regenerated silk fibroin was proposed as a structural material in tissue engineering applications, mainly for application in bone. The protocol allows us to obtain a compact non-porous material with a compression modulus in the order of a Giga Pascal in dry conditions (and in the order of tens of MPa in wet conditions). This material is produced by compressing a lyophilized silk fibroin powder or sponge into a mold temperature higher than the glass transition temperature. The main purpose of the produced resin was the osteofixation and other structural applications in which the lack of porosity was not an issue. In this work, we introduced the use of citric acid in the thermoplastic molding protocol of silk fibroin to obtain porosity inside the structural material. The citric acid powder during the compression acted as a template for the pore formation. The mean pore diameter achieved by the addition of the higher amount of citric acid was around 5 μm. In addition, citric acid could effectively crosslink the silk fibroin chain, improving its mechanical strength. This effect was proved both by evaluating the compression modulus (the highest value recorded was 77 MPa in wet conditions) and by studying the spectra obtained by Fourier transform infrared spectroscopy. This protocol may be applied in the near future to the production of structural bone scaffolds. Full article
(This article belongs to the Special Issue Synthesis, Optimization, and Reuse of Sustainable Bio-Based Materials)
►▼ Show Figures

Figure 1

17 pages, 5382 KiB  
Article
Green Synthesis, Characterization, and Empirical Thermal Conductivity Assessment of ZnO Nanofluids for High-Efficiency Heat-Transfer Applications
by Meriem Jebali, Gianpiero Colangelo and Ana Isabel Gómez-Merino
Materials 2023, 16(4), 1542; https://doi.org/10.3390/ma16041542 - 12 Feb 2023
Cited by 2 | Viewed by 1987
Abstract
ZnO nanoparticles were synthesized using lemon juice and zinc nitrate (1:1) through the green method. The structure of the biosynthesized ZnO nanoparticles was analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The morphology and the size of [...] Read more.
ZnO nanoparticles were synthesized using lemon juice and zinc nitrate (1:1) through the green method. The structure of the biosynthesized ZnO nanoparticles was analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The morphology and the size of ZnO nanoparticles were elucidated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The powder was highly dispersed and irregularly shaped and the size of the nanoparticles ranged from 28 to 270 nm, depending on the shape of the particles. Thermal conductivity of the biosynthesized ZnO PG/W mixture 40:60 (v/v) nanofluids was measured within the temperature range of 20–70 °C. Experimental results revealed a linear increase in thermal conductivity with the rise of temperature and volume fraction. The enhancement of this parameter with temperature was probably due to the different shapes of the former agglomerates. They were broken by the thermal energy in aggregates of different forms. A correlation of these structures with temperature was established. Finally, an empirical model was developed for predicting thermal conductivity with particle volume fraction and temperature. Full article
(This article belongs to the Special Issue Green Synthesis and Applications of Metallic Nanoparticles)
►▼ Show Figures

Graphical abstract

13 pages, 2105 KiB  
Article
Analyzing the Bolometric Performance of Vanadium Oxide Thin Films Modified by Carbon Nanotube Dispersions
by Usha Philipose, Chris Littler, Yan Jiang, Alia Naciri, Michael Harcrow and A. J. Syllaios
Materials 2023, 16(4), 1534; https://doi.org/10.3390/ma16041534 - 12 Feb 2023
Cited by 1 | Viewed by 1791
Abstract
The influence of carbon nanotube (CNT) dispersions on the electrical properties and noise signal amplitude of VOx films is investigated. For a critical range of the CNT dispersion density on VOx films, the intrinsic properties of the [...] Read more.
The influence of carbon nanotube (CNT) dispersions on the electrical properties and noise signal amplitude of VOx films is investigated. For a critical range of the CNT dispersion density on VOx films, the intrinsic properties of the VOx films are modified by the CNTs. The CNT concentrations reported in this work are about 0.3 μg/cm2 and 1.6 μg/cm2, allowing for low density and high density dispersions on the VOx film surface to be investigated. These values are higher than the percolation threshold of about 0.12 μg/cm2 for these films. The composite film exhibits a significant reduction in the temperature coefficient of resistance (TCR) (from ≈3.8% K−1 to ≈0.3% K−1) for high density dispersions. In contrast, while VOx–CNT composites with low density single wall CNT dispersions exhibit no significant change in TCR values, an approximate two orders of magnitude reduction in the low frequency 1/f noise is measured. The noise signal amplitude measured at 0.1 V and at 1.0 Hz reduces from 6 × 10−5V/(Hz) for VOx films to 5 × 10−7V/(Hz) for the low density SWCNT dispersion on VOx film and to 3 × 10−6V/(Hz) for the low density MWCNT dispersion on VOx film. The CNT concentration is the critical factor for yielding the observed changes in conductivity and low frequency noise. The results presented in this work provide a better understanding of VOx-based composites, thereby enabling the development of new, versatile and functional materials for device applications. Full article
(This article belongs to the Special Issue Feature Papers in Thin Films and Interfaces)
►▼ Show Figures

Figure 1

21 pages, 3534 KiB  
Article
Parametric Study of the Influence of Nonlinear Elastic Characteristics of Rail Pads on Wheel–Rail Vibrations
by Traian Mazilu, Mădălina Dumitriu and Ionuț-Radu Răcănel
Materials 2023, 16(4), 1531; https://doi.org/10.3390/ma16041531 - 12 Feb 2023
Cited by 4 | Viewed by 1416
Abstract
The rail pad is the elastic element between the rail and the sleeper that has the role of absorbing the mechanical stresses from the rail and reducing the vibrations and shocks generated by wheel–rail interactions. In this paper, the problem of the influence [...] Read more.
The rail pad is the elastic element between the rail and the sleeper that has the role of absorbing the mechanical stresses from the rail and reducing the vibrations and shocks generated by wheel–rail interactions. In this paper, the problem of the influence of the variability of the nonlinear load-deformation characteristic of rail pads (resulting from the manufacturing process) on wheel–rail vibrations is investigated. The limit load-deformation characteristics of a manufactured rail pad and the medium load-deformation characteristic resulting as the arithmetic mean of the two are considered. The nonlinear load-deformation characteristic of the ballast is also considered. All these characteristics are approximated with the help of the bilinear function and are implemented in a track model consisting of an infinite Euler-Bernoulli beam placed on a two-elastic layer continuous foundation with inertial insertion, resulting in a model with an inhomogeneous foundation. The parameters of the inhomogeneous foundation are established from the equilibrium condition under a static load. Wheel–rail vibrations are studied in terms of the contact force and the acceleration of the rail and wheel. The influence of the variability of the elastic characteristics of the rail pad manifests itself in the field of medium frequencies, which amplify or attenuate the vibration levels in certain bands of one-third of an octave. Full article
(This article belongs to the Special Issue Research and Modeling of Materials Fatigue and Fracture)
►▼ Show Figures

Figure 1

15 pages, 8380 KiB  
Article
Antimicrobial Properties of TiNbSn Alloys Anodized in a Sulfuric Acid Electrolyte
by Yu Mori, Satoko Fujimori, Hiroaki Kurishima, Hiroyuki Inoue, Keiko Ishii, Maya Kubota, Kazuyoshi Kawakami, Naoko Mori, Toshimi Aizawa and Naoya Masahashi
Materials 2023, 16(4), 1487; https://doi.org/10.3390/ma16041487 - 10 Feb 2023
Cited by 2 | Viewed by 1500
Abstract
TiNbSn alloy is a high-performance titanium alloy which is biosafe, strong, and has a low Young’s modulus. TiNbSn alloy has been clinically applied as a material for orthopedic prosthesis. Anodized TiNbSn alloys with acetic and sulfuric acid electrolytes have excellent biocompatibility for osseointegration. [...] Read more.
TiNbSn alloy is a high-performance titanium alloy which is biosafe, strong, and has a low Young’s modulus. TiNbSn alloy has been clinically applied as a material for orthopedic prosthesis. Anodized TiNbSn alloys with acetic and sulfuric acid electrolytes have excellent biocompatibility for osseointegration. Herein, TiNbSn alloy was anodized in a sulfuric acid electrolyte to determine the antimicrobial activity. The photocatalytic activities of the anodic oxide alloys were investigated based on their electronic band structure and crystallinity. In addition, the cytotoxicity of the anodized TiNbSn alloy was evaluated using cell lines of the osteoblast and fibroblast lineages. The antimicrobial activity of the anodic oxide alloy was assessed according to the ISO 27447 using methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Escherichia coli. The anodic oxide comprised rutile and anatase titanium dioxide (TiO2) and exhibited a porous microstructure. A well-crystallized rutile TiO2 phase was observed in the anodized TiNbSn alloy. The methylene blue degradation tests under ultraviolet illumination exhibited photocatalytic activity. In antimicrobial tests, the anodized TiNbSn alloy exhibited robust antimicrobial activities under ultraviolet illumination for all bacterial species, regardless of drug resistance. Therefore, the anodized TiNbSn alloy can be used as a functional biomaterial with low Young’s modulus and excellent antimicrobial activity. Full article
(This article belongs to the Special Issue Mechanical Behavior of Biological and Bio-Inspired Materials)
►▼ Show Figures

Figure 1

15 pages, 6239 KiB  
Article
Mammalian Oocyte Analysis by MALDI MSI with Wet-Interface Matrix Deposition Technique
by Anna Bodzon-Kulakowska, Wiesława Młodawska, Przemyslaw Mielczarek, Dorota Lachowicz, Piotr Suder and Marek Smoluch
Materials 2023, 16(4), 1479; https://doi.org/10.3390/ma16041479 - 9 Feb 2023
Cited by 2 | Viewed by 1566
Abstract
Oocytes are a special kind of biological material. Here, the individual variability of a single cell is important. It means that the opportunity to obtain information about the lipid content from the analysis of a single cell is significant. In our study, we [...] Read more.
Oocytes are a special kind of biological material. Here, the individual variability of a single cell is important. It means that the opportunity to obtain information about the lipid content from the analysis of a single cell is significant. In our study, we present a method for lipid analysis based on the MALDI-based mass spectrometry imaging (MSI) approach. Our attention was paid to the sample preparation optimization with the aid of a wet-interface matrix deposition system (matrix spraying). Technical considerations of the sample preparation process, such as the number of matrix layers and the position of the spraying nozzle during the matrix deposition, are presented in the article. Additionally, we checked if changing the 2,5-dihydroxybenzoic acid (DHB) and 9-Aminoacridine (9AA) matrix concentration and their solvent composition may improve the analysis. Moreover, the comparison of paraformaldehyde-fixed versus nonfixed cell analysis was performed. We hope that our approach will be helpful for those working on lipid analyses in extraordinary material such as a single oocyte. Our study may also offer clues for anybody interested in single-cell analysis with the aid of MALDI mass spectrometry imaging and the wet-interface matrix deposition method. Full article
(This article belongs to the Special Issue Mass Spectrometry in Materials Science)
►▼ Show Figures

Figure 1

10 pages, 3179 KiB  
Article
Strong Plasmon-Mie Resonance in Si@Pd Core-Ω Shell Nanocavity
by Haomin Guo, Qi Hu, Chengyun Zhang, Haiwen Liu, Runmin Wu and Shusheng Pan
Materials 2023, 16(4), 1453; https://doi.org/10.3390/ma16041453 - 9 Feb 2023
Cited by 2 | Viewed by 2296
Abstract
The surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) can be used to enhance the generation of the hot electrons in plasmon metal nanocavity. In this paper, Pd nanomembrane (NMB) is sputtered on the surface of Si nanosphere (NS) on glass [...] Read more.
The surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) can be used to enhance the generation of the hot electrons in plasmon metal nanocavity. In this paper, Pd nanomembrane (NMB) is sputtered on the surface of Si nanosphere (NS) on glass substrate to form the Si@Pd core-Ω shell nanocavity. A plasmon-Mie resonance is induced in the nanocavity by coupling the plasmon resonance with the Mie resonance to control the optical property of Si NS. When this nanocavity is excited by near-infrared-1 (NIR-1, 650 nm–900 nm) femtosecond (fs) laser, the luminescence intensity of Si NS is dramatically enhanced due to the synergistic interaction of plasmon and Mie resonance. The generation of resonance coupling regulates resonant mode of the nanocavity to realize multi-dimensional nonlinear optical response, which can be utilized in the fields of biological imaging and nanoscale light source. Full article
(This article belongs to the Special Issue Synthesis and Application of Advanced Optical and Optoelectronic Functional Materials)
►▼ Show Figures

Figure 1

12 pages, 2084 KiB  
Article
Enhanced Thermoelectric Properties of Misfit Bi2Sr2-xCaxCo2Oy: Isovalent Substitutions and Selective Phonon Scattering
by Arindom Chatterjee, Ananya Banik, Alexandros El Sachat, José Manuel Caicedo Roque, Jessica Padilla-Pantoja, Clivia M. Sotomayor Torres, Kanishka Biswas, José Santiso and Emigdio Chavez-Angel
Materials 2023, 16(4), 1413; https://doi.org/10.3390/ma16041413 - 8 Feb 2023
Cited by 2 | Viewed by 1725
Abstract
Layered Bi-misfit cobaltates, such as Bi2Sr2Co2Oy, are the natural superlattice of an electrically insulating rocksalt (RS) type Bi2Sr2O4 layer and electrically conducting CoO2 layer, stacked along the crystallographic c-axis. [...] Read more.
Layered Bi-misfit cobaltates, such as Bi2Sr2Co2Oy, are the natural superlattice of an electrically insulating rocksalt (RS) type Bi2Sr2O4 layer and electrically conducting CoO2 layer, stacked along the crystallographic c-axis. RS and CoO2 layers are related through charge compensation reactions (or charge transfer). Therefore, thermoelectric transport properties are affected when doping or substitution is carried out in the RS layer. In this work, we have shown improved thermoelectric properties of spark plasma sintered Bi2Sr2-xCaxCo2Oy alloys (x = 0, 0.3 and 0.5). The substitution of Ca atoms affects the thermal properties by introducing point-defect phonon scattering, while the electronic conductivity and thermopower remain unaltered. Full article
(This article belongs to the Special Issue Thermoelectric Materials: Progress and Their Applications)
►▼ Show Figures

Figure 1

22 pages, 8744 KiB  
Article
Abnormal Eu3+ → Eu2+ Reduction in Ca9−xMnxEu(PO4)7 Phosphors: Structure and Luminescent Properties
by Elena V. Sipina, Dmitry A. Spassky, Nataliya R. Krutyak, Vladimir A. Morozov, Evgenia S. Zhukovskaya, Alexei A. Belik, Mikhail S. Manylov, Bogdan I. Lazoryak and Dina V. Deyneko
Materials 2023, 16(4), 1383; https://doi.org/10.3390/ma16041383 - 7 Feb 2023
Cited by 5 | Viewed by 1924
Abstract
β-Ca3(PO4)2-type phosphors Ca9−xMnxEu(PO4)7 have been synthesized by high-temperature solid-phase reactions. The crystal structure of Ca8MnEu(PO4)7 was characterized by synchrotron X-ray diffraction. The phase transitions, [...] Read more.
β-Ca3(PO4)2-type phosphors Ca9−xMnxEu(PO4)7 have been synthesized by high-temperature solid-phase reactions. The crystal structure of Ca8MnEu(PO4)7 was characterized by synchrotron X-ray diffraction. The phase transitions, magnetic and photoluminescence (PL) properties were studied. The abnormal reduction Eu3+ → Eu2+ in air was observed in Ca9−xMnxEu(PO4)7 according to PL spectra study and confirmed by X-ray photoelectron spectroscopy (XPS). Eu3+ shows partial reduction and coexistence of Eu2+/3+ states. It reflects in combination of a broad band from the Eu2+ 4f65d1 → 4f7 transition and a series of sharp lines attributed to 5D0 → 7FJ transitions of Eu3+. Eu2+/Eu3+ ions are redistributed among two crystal sites, M1 and M3, while Mn2+ fully occupies octahedral site M5 in Ca8MnEu(PO4)7. The main emission band was attributed to the 5D0 → 7F2 electric dipole transition of Eu3+ at 395 nm excitation. The abnormal quenching of Eu3+ emission was observed in Ca9−xMnxEu(PO4)7 phosphors with doping of the host by Mn2+ ions. The phenomena of abnormal reduction and quenching were discussed in detail. Full article
(This article belongs to the Special Issue Advanced Materials for Optical and Luminescence Applications)
►▼ Show Figures

Figure 1

33 pages, 12603 KiB  
Article
Application of the ps−Version of the Finite Element Method to the Analysis of Laminated Shells
by Cheng Angelo Yan and Riccardo Vescovini
Materials 2023, 16(4), 1395; https://doi.org/10.3390/ma16041395 - 7 Feb 2023
Cited by 2 | Viewed by 1465
Abstract
The development of accurate and efficient numerical methods is of crucial importance for the analysis and design of composite structures. This is even more true in the presence of variable stiffness (VS) configurations, where intricate load paths can be responsible for complex and [...] Read more.
The development of accurate and efficient numerical methods is of crucial importance for the analysis and design of composite structures. This is even more true in the presence of variable stiffness (VS) configurations, where intricate load paths can be responsible for complex and localized stress profiles. In this work, we present the ps−version of the finite elements method (ps−FEM), a novel FE approach which can perform global/local analysis through different refinement strategies efficiently and easily. Within this framework, the global behavior is captured through a p−refinement by increasing the polynomial order of the elements. For the local one, a mesh−superposition technique, called s−refinement, is used to improve locally the solution by defining a local/fine mesh overlaid to the global/coarse one. The combination of p− and s−refinements enables us to achieve excellent accuracy−to−cost ratios. This paper aims to present the numerical formulation and the implementation aspects of this novel approach to VS composite shell analysis. Numerical tests are reported to illustrate the potential of the method. The results provide a clear insight of its potential to guarantee fast convergence and easy mesh refinement where needed. Full article
(This article belongs to the Special Issue Feature Papers in Materials Simulation and Design)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying article 401-450 on page 9 of 34.

Go to page    first_page chevron_left 7 8 9 10 11 chevron_right last_page
Back to TopTop