Crystals

12 pages, 3148 KiB

Open AccessFeature PaperArticle

Micro-Nanoarchitectonics of Ga₂O₃/GaN Core-Shell Rod Arrays for High-Performance Broadband Ultraviolet Photodetection

by Ruifan Tang, Guanqi Li, Xun Hu, Na Gao, Jinchai Li, Kai Huang, Junyong Kang and Rong Zhang

Crystals 2023, 13(2), 366; https://doi.org/10.3390/cryst13020366 - 20 Feb 2023

Cited by 3 | Viewed by 1976

Abstract

This study presents broadband ultraviolet photodetectors (BUV PDs) based on Ga₂O₃/GaN core-shell micro-nanorod arrays with excellent performance. Micro-Nanoarchitectonics of Ga₂O₃/GaN core-shell rod arrays were fabricated with high-temperature oxidization of GaN micro-nanorod arrays. The PD based [...] Read more.

This study presents broadband ultraviolet photodetectors (BUV PDs) based on Ga₂O₃/GaN core-shell micro-nanorod arrays with excellent performance. Micro-Nanoarchitectonics of Ga₂O₃/GaN core-shell rod arrays were fabricated with high-temperature oxidization of GaN micro-nanorod arrays. The PD based on the microrod arrays exhibited an ultrahigh responsivity of 2300 A/W for 280 nm at 7 V, the peak responsivity was approximately 400 times larger than those of the PD based on the planar Ga₂O₃/GaN film. The responsivity was over 1500 A/W for the 270–360 nm band at 7 V. The external quantum efficiency was up to 1.02 × 10⁶% for 280 nm. Moreover, the responsivity was further increased to 2.65 × 10⁴ A/W for 365 nm and over 1.5 × 10⁴ A/W for 270–360 nm using the nanorod arrays. The physical mechanism may have been attributed to the large surface area of the micro-nanorods coupled with the Ga₂O₃/GaN heterostructure, which excited more photogenerated holes to be blocked at the Ga₂O₃ surface and Ga₂O₃/GaN interface, resulting in a larger internal gain. The overall high performance coupled with large-scale production makes it a promising candidate for practical BUV PD. Full article

(This article belongs to the Special Issue Recent Advances in III-Nitride Semiconductors)

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14 pages, 4470 KiB

Open AccessArticle

Prediction of Crack Propagation of Nano-Crystalline Coating Material Prepared from (SAM2X5): Experimentally and Numerically

by Hamid Al-Abboodi, Huiqing Fan and Mohammed Al-Bahrani

Crystals 2023, 13(2), 365; https://doi.org/10.3390/cryst13020365 - 20 Feb 2023

Cited by 1 | Viewed by 1222

Abstract

The fracture and crack growth of materials can be practically and conveniently predicted through numerical analysis and linear elastics fracture mechanics. On this basis, the current study aims to present experimental work supported by a numerical technique for mimicking the crack propagation by [...] Read more.

The fracture and crack growth of materials can be practically and conveniently predicted through numerical analysis and linear elastics fracture mechanics. On this basis, the current study aims to present experimental work supported by a numerical technique for mimicking the crack propagation by Version 5.6 of COMSOL Multiphysics (version 5.6), used for the simulation of the coating made from Fe-based amorphous material with a thickness of 300 µm. The paper shows the effects of mixed-mode loading on cohesive zone parameters attained from load-crack mouth opening displacement (CMOD) curves. The microstructure dominates the fracture, which in mode I is altered from all-transgranular cleavage to nearly all-intergranular structure in mode II. Two common criteria for failure are linked to the mixed-mode results: Maximum energy release rate criterion (Maximum G) and maximum tensile stress criterion (Maximum S). However, distinguishing between the two criteria is made impossible by the large scatter in the data. The stress intensity factor is the basis for the. The stress intensity factor is the leading parameter facilitated by the singular element and should be estimated with accuracy. With the aim of comparing each criterion and illustrating the numerical schemes’ robustness, a number of examples are presented. It can be concluded that the Maximum G and Maximum S were successful and accurate in predicting the propagation of the Fe-based amorphous material prepared on mild steel. Full article

(This article belongs to the Section Crystal Engineering)

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13 pages, 2884 KiB

Open AccessArticle

The Effect of Instability of KCl:Na Single Crystals

by Kuanyshbek Shunkeyev, Aizhan Tilep, Shynar Sagimbayeva, Zhiger Ubaev and Aleksandr Lushchik

Crystals 2023, 13(2), 364; https://doi.org/10.3390/cryst13020364 - 20 Feb 2023

Cited by 3 | Viewed by 1170

Abstract

For the first time, the stability of KCl single crystals doped with sodium impurity ions was analyzed via the optical absorption and luminescence methods. Using the characteristic bands of optical absorption, as well as of X-ray and tunnel luminescence, ascribed to radiation defects [...] Read more.

For the first time, the stability of KCl single crystals doped with sodium impurity ions was analyzed via the optical absorption and luminescence methods. Using the characteristic bands of optical absorption, as well as of X-ray and tunnel luminescence, ascribed to radiation defects and exciton-like formations localized near sodium impurity, the removal of Na⁺ ions from regular cation sites into nanosized clusters in KCl:Na crystals stored for a long time at room temperature was demonstrated. At the same time, the subsequent annealing of such “decayed” crystals at high temperature (400–700 °C) led to a partial incorporation of sodium impurity ions back into cation sites and the restoration of a homogeneous distribution of Na⁺ in the KCl:Na lattice. With an increase in the quenching temperature, the restoration degree continuously increased until it reached the saturation level (about 80% of the characteristics of a freshly grown crystal). The detectable/disappearing X-ray-induced absorption bands at 6.3 and 3.5 eV (respectively ascribed to interstitial chlorine ions and atoms localized near Na⁺), as well as the luminescence bands at 2.8 and 3.1 eV, typical of recombinationally generated exciton-like formations near Na⁺ or Na⁺-Na⁺, were the indicators of sodium ion redistribution in the crystal lattice. Full article

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11 pages, 2180 KiB

Open AccessArticle

Colorimetric Plasmonic Hydrogen Gas Sensor Based on One-Dimensional Nano-Gratings

by Majid Zarei, Seyedeh M. Hamidi and K. -W. -A. Chee

Crystals 2023, 13(2), 363; https://doi.org/10.3390/cryst13020363 - 20 Feb 2023

Cited by 2 | Viewed by 1752

Abstract

Plasmonic hydrogen gas sensors have become widely used in recent years due to their low cost, reliability, safety, and measurement accuracy. In this paper, we designed, optimized, and fabricated a palladium (Pd)-coated nano-grating-based plasmonic hydrogen gas sensor; and investigated using the finite-difference time-domain [...] Read more.

Plasmonic hydrogen gas sensors have become widely used in recent years due to their low cost, reliability, safety, and measurement accuracy. In this paper, we designed, optimized, and fabricated a palladium (Pd)-coated nano-grating-based plasmonic hydrogen gas sensor; and investigated using the finite-difference time-domain method and experimental spectral reflectance measurements, the calibrated effects of hydrogen gas exposure on the mechano-optical properties of the Pd sensing layer. The nanostructures were fabricated using DC sputter deposition onto a one-dimensional nano-grating optimized with a thin-film gold buffer to extend the optical response dynamic range and performance stability; the color change sensitivity of the Pd surface layer was demonstrated for hydrogen gas concentrations as low as 0.5 vol.%, up to 4 vol.%, based on the resonance wavelength shift within the visible band corresponding to the reversible phase transformation. Visual color change detection of even the smallest hydrogen concentrations indicated the high sensitivity of the gas sensor. Our technique has potential for application to high-accuracy portable plasmonic sensors compatible with biochemical sensing with smartphones. Full article

(This article belongs to the Special Issue 1D and 2D Nanomaterials for Sensor Applications)

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15 pages, 4658 KiB

Open AccessArticle

Structural and Spectroscopic Effects of Li⁺ Substitution for Na⁺ in Li_xNa_1−xCaLa_0.5Er_0.05Yb_0.45(MoO₄)₃ Upconversion Scheelite-Type Phosphors

by Chang Sung Lim, Aleksandr Aleksandrovsky, Maxim Molokeev, Aleksandr Oreshonkov and Victor Atuchin

Crystals 2023, 13(2), 362; https://doi.org/10.3390/cryst13020362 - 20 Feb 2023

Cited by 8 | Viewed by 1311

Abstract

New triple molybdates Li_xNa_1−xCaLa_0.5(MoO₄)₃:Er³⁺0.05/Yb³⁺0.45 (x = 0, 0.05, 0.1, 0.2, 0.3) were manufactured successfully using the microwave-assisted sol-gel-based technique (MAS). Their room-temperature crystal structures were determined in space group [...] Read more.

New triple molybdates Li_xNa_1−xCaLa_0.5(MoO₄)₃:Er³⁺0.05/Yb³⁺0.45 (x = 0, 0.05, 0.1, 0.2, 0.3) were manufactured successfully using the microwave-assisted sol-gel-based technique (MAS). Their room-temperature crystal structures were determined in space group I4₁/a by Rietveld analysis. The compounds were found to have a scheelite-type structure. In Li-substituted samples, the sites of big cations were occupied by a mixture of (Li, Na, La, Er, Yb) ions, which provided a linear cell volume decrease with the Li content increase. The increased upconversion (UC) efficiency and Raman spectroscopic properties of the phosphors were discussed in detail. The mechanism of optimization of upconversion luminescence upon Li content variation was shown to be due to the control of excitation/energy transfer channel, while the control of luminescence channels played a minor role. The UC luminescence maximized at lithium content x = 0.05. The mechanism of UC optimization was shown to be due to the control of excitation/energy transfer channel, while the control of luminescence channels played a minor role. Over the whole spectral range, the Raman spectra of Li_xNa_1−xCaLa_0.5(MoO₄)₃ doped with Er³⁺ and Yb³⁺ ions were totally superimposed with the luminescence signal of Er³⁺ ions, and increasing the Li⁺ content resulted in the difference of Er³⁺ multiple intensity. The density functional theory calculations with the account for the structural disorder in the system of Li, Na, Ca, La, Er and Yb ions revealed the bandgap variation from 3.99 to 4.137 eV due to the changing of Li content. It was found that the direct electronic transition energy was close to the indirect one for all compounds. The determined chromaticity points (ICP) of the LiNaCaLa(MoO₄)₃:Er³⁺,Yb³⁺ phosphors were in good relation to the equal-energy point in the standard CIE (Commission Internationale de L’Eclairage) coordinates. Full article

(This article belongs to the Special Issue Rare Earths-Doped Materials (Volume II))

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5 pages, 230 KiB

Open AccessEditorial

Recent Progress in Theoretical Studies and Computer Modeling of Non-Covalent Interactions

by Alexander S. Novikov

Crystals 2023, 13(2), 361; https://doi.org/10.3390/cryst13020361 - 20 Feb 2023

Cited by 2 | Viewed by 1163

Abstract

It is not at all surprising that the topic of non-covalent interactions, a key pillar of supramolecular chemistry, has seen interest grow enormously within the last decade [...] Full article

(This article belongs to the Special Issue Theoretical Investigation on Non-covalent Interactions)

14 pages, 5310 KiB

Open AccessArticle

A Metamaterial-Based Double-Sided Bowtie Antenna for Intelligent Transport System Communications Operating in Public Safety Band

by Rayan Hamza Alsisi, Arshad Karimbu Vallappil and Hafiz Abdul Wajid

Crystals 2023, 13(2), 360; https://doi.org/10.3390/cryst13020360 - 19 Feb 2023

Viewed by 1774

Abstract

In this paper, a compact design and new structure of bowtie antenna with dual-band characteristics for the 5G and public safety bands in intelligent transport systems (ITS) is presented. The antenna consists of a double-sided bowtie radiating patch with partial ground plane. A [...] Read more.

In this paper, a compact design and new structure of bowtie antenna with dual-band characteristics for the 5G and public safety bands in intelligent transport systems (ITS) is presented. The antenna consists of a double-sided bowtie radiating patch with partial ground plane. A triangular complementary split-ring resonator (TCSRR) metamaterial (MTM) structure was etched on the radiating patch, to develop a dual band and a single notch band between 3.85 and 4.65 GHz. The proposed antenna had an overall size of 36 × 36 mm² and was fabricated using a FR4 substrate with a thickness and dielectric permittivity (ε_r) of 1.6 mm and 4.3, respectively. CST microwave studio software was used for the design of antenna. The measured frequency results show impedance bandwidths of 3.45–3.85 GHz and 4.65–5.4 GHz, for a voltage standing wave ratio (VSWR) less than 2. The proposed antenna operates at 3.5 GHz and 4.9 GHz, providing bandwidths of 400 MHz and 750 MHz, respectively, which cover the 5G and public safety bands. A prototype was fabricated and measured based upon optimal parameters, and the experimental results showed consistency with the simulation results. The proposed antenna provided a simulated/measured gain of 5.64 dBi/5 dBi and 4 dBi/3.7 dBi at 3.5 GHz and 4.9 GHz, respectively. The enhanced bandwidth and better gain results of the proposed antenna make it an ideal candidate for an ITS operating in the 5G and public safety bands. Full article

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15 pages, 8290 KiB

Open AccessArticle

Predicting the Level of Background Current Noise in Graphene Biosensor through a Non-Covalent Functionalization Process

by Chao-yi Zhu, Zi-hong Lin, Da-yong Zhang, Jing-yuan Shi, Song-ang Peng and Zhi Jin

Crystals 2023, 13(2), 359; https://doi.org/10.3390/cryst13020359 - 19 Feb 2023

Cited by 1 | Viewed by 1528

Abstract

The rapid worldwide spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a series of problems. Detection platforms based on graphene field-effect transistors (GFETs) have been proposed to achieve a rapid diagnosis of SARS-CoV-2 antigen or antibody. For GFET-based biosensors, [...] Read more.

The rapid worldwide spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a series of problems. Detection platforms based on graphene field-effect transistors (GFETs) have been proposed to achieve a rapid diagnosis of SARS-CoV-2 antigen or antibody. For GFET-based biosensors, the graphene surface usually needs to be functionalized to immobilize the bioreceptor and the non-covalent approach is preferred for functionalization because it is believed not to significantly alter the electronic properties of graphene. However, in this work, the non-covalent functionalization introduced by 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE) was determined to lead to different changes in electrical properties in graphene samples with different defect densities. The fabricated graphene biosensor can successfully detect SARS-CoV-2 antigen with a concentration as low as 0.91 pg/mL. Further, by careful comparison, we determined that, for GFET fabricated on graphene with a higher defect density, the current variation caused by PBASE modification is greater and the background current noise in the subsequent antigen detection is also larger. Based on this relationship, we can predict the background current noise of the biosensors by evaluating the current change induced by the modification and screen the devices at an early stage of graphene biosensor fabrication for process optimization. Full article

(This article belongs to the Special Issue 2D Crystalline Nanomaterials)

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14 pages, 2999 KiB

Open AccessArticle

Effect of Few-Layer Graphene on the Properties of Mixed Polyolefin Waste Stream

by S. M. Nourin Sultana, Emna Helal, Giovanna Gutiérrez, Eric David, Nima Moghimian and Nicole R. Demarquette

Crystals 2023, 13(2), 358; https://doi.org/10.3390/cryst13020358 - 19 Feb 2023

Cited by 6 | Viewed by 1897

Abstract

This work demonstrates how the addition of few-layer graphene (FLG) influences the processability and mechanical properties of the mixed polyolefin waste stream (R-(PE/PP)). Three different types of compounds were investigated: (1) R-(PE/PP) with FLG; (2) blends of R-(PE/PP) with prime polyethylene (PE) or [...] Read more.

This work demonstrates how the addition of few-layer graphene (FLG) influences the processability and mechanical properties of the mixed polyolefin waste stream (R-(PE/PP)). Three different types of compounds were investigated: (1) R-(PE/PP) with FLG; (2) blends of R-(PE/PP) with prime polyethylene (PE) or polypropylene (PP) or PP copolymer; and (3) R-(PE/PP) with both the prime polymer and FLG. The processability was assessed by measuring the torque during melt extrusion, the melt flow index (MFI), and viscosity of the compounds. Investigations of the processability and mechanical properties of the composites indicate that the presence of FLG can reinforce the composites without hindering the processability, an unusual but desired feature of rigid fillers. A maximum increase in tensile strength by 9%, flexural strength by 23%, but a reduction in impact strength were observed for the compounds containing R-(PE/PP), 4 wt.% FLG, and 9 wt.% prime PP. The addition of FLG concentrations higher than 4 wt.% in R-(PE/PP), however, resulted in higher tensile and flexural properties while preserving the impact strength. Remarkably, the addition of 10 wt.% FLG increased the impact strength of the composite by 9%. This increase in impact strength is attributed to the dominant resistance of the rigid FLG particles to crack propagation. Full article

(This article belongs to the Special Issue Advanced Technologies in Graphene-Based Materials)

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20 pages, 4717 KiB

Open AccessArticle

Influence of Grain Size on Mechanical Properties of a Refractory High Entropy Alloy under Uniaxial Tension

by Orlando Deluigi, Felipe Valencia, Diego R. Tramontina, Nicolás Amigo, Javier Rojas-Nunez and Eduardo M. Bringa

Crystals 2023, 13(2), 357; https://doi.org/10.3390/cryst13020357 - 19 Feb 2023

Cited by 2 | Viewed by 2776

Abstract

There is a growing interest in High Entropy Alloys (HEAs) due to their outstanding mechanical properties. Most simulation studies have focused on face-centered cubic (fcc) HEAs; however, bcc HEAs can offer a larger elastic modulus and plastic yielding, thus, becoming possible candidates for [...] Read more.

There is a growing interest in High Entropy Alloys (HEAs) due to their outstanding mechanical properties. Most simulation studies have focused on face-centered cubic (fcc) HEAs; however, bcc HEAs can offer a larger elastic modulus and plastic yielding, thus, becoming possible candidates for the next generation of refractory materials. In this work, we focus on molecular dynamics (MD) simulations of bcc HfNbTaZr nanocrystalline samples, with a grain size (d) between 5 and 17 nm, deformed under tension at 300 K. The elastic modulus increases with the grain size and reaches a plateau near 10 nm. We find the typical inverse Hall–Petch (HP) behavior with yield strength, ultimate tensile stress (UTS), and flow stress increasing with d. Up to 12 nm, there are contributions from dislocations and twins; however, grain boundary (GB) activity dominates deformation. For the 5 nm grains, the GB disorder extends and leads to extensive amorphization and grain size reduction. For

d > 10

nm, there is a HP-type behavior with dislocations and twinning controlling deformation. For this regime, there is hardening at large strains. Compared to bcc single metal samples, the HP maximum of this HEA appears at a lower grain size, and this could be related to the chemical complexity facilitating dislocation nucleation. We use machine learning to help understand deformation regimes. We also compare our results to a single crystal (SC) HfNbTaZr HEA deformed along [001] and find that the single crystal is weaker than the nanocrystalline samples. The single crystal deforms initially by twinning and then rapidly by dislocation multiplication, leading to strong hardening. It has been proposed that edge dislocations play a major role in bcc HEA plasticity, and we also analyze the relative contributions of edge versus screw dislocations during deformation for both single crystal and nanocrystalline samples. Full article

(This article belongs to the Special Issue Dislocation Mechanics of Crystal/Polycrystal Mechanical Strength Properties)

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12 pages, 2125 KiB

Open AccessArticle

The Effect of Titanium Oxyfluoride Morphology on Photocatalytic Activity of Fluorine-Doped Titanium(IV) Oxide

by Marta Kowalkińska, Jakub Karczewski and Anna Zielińska-Jurek

Crystals 2023, 13(2), 356; https://doi.org/10.3390/cryst13020356 - 19 Feb 2023

Cited by 1 | Viewed by 1520

Abstract

Titanium oxyfluoride (TiOF₂) is a metastable product that can be obtained in a fluorine-rich environment. This material can also be a valuable precursor in the synthesis of titanium(IV) oxide (TiO₂). However, the effect of TiOF₂ morphology on the [...] Read more.

Titanium oxyfluoride (TiOF₂) is a metastable product that can be obtained in a fluorine-rich environment. This material can also be a valuable precursor in the synthesis of titanium(IV) oxide (TiO₂). However, the effect of TiOF₂ morphology on the physicochemical properties of TiO₂ has not been studied so far. In this work, single-phase TiOF₂ was prepared by a solvothermal method. The as-synthesized samples exhibited a variety of morphologies, including different shapes and crystallite sizes. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS), surface area measurements, thermal gravimetric analysis (TGA) and UV–vis diffuse reflectance spectroscopy (DR/UV–vis). Furthermore, TiOF₂ samples were used as precursors in the synthesis of fluorine-doped titanium(IV) oxide and applied in photocatalytic phenol degradation under UV-vis light. The experiments showed that the crystallite size of the precursor, as well as the number of fluoride ions used in the synthesis, were the predominant factors that affected the photocatalytic activity of the final photocatalyst. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Photocatalytic Technologies)

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13 pages, 4071 KiB

Open AccessArticle

Ion-Beam Synthesis of Structure-Oriented Iron Nanoparticles in Single-Crystalline Rutile TiO₂

by Iskander R. Vakhitov, Nikolay M. Lyadov, Vladimir I. Vdovin, Anton K. Gutakovskii, Vladimir I. Nuzhdin, Lenar R. Tagirov and Rustam I. Khaibullin

Crystals 2023, 13(2), 355; https://doi.org/10.3390/cryst13020355 - 18 Feb 2023

Viewed by 1187

Abstract

Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fe⁺ ions were implanted in high fluences of (0.5 ÷ 1.5) × 10¹⁷ ion/cm² into an oxide semiconductor and single-crystalline TiO₂ [...] Read more.

Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fe⁺ ions were implanted in high fluences of (0.5 ÷ 1.5) × 10¹⁷ ion/cm² into an oxide semiconductor and single-crystalline TiO₂ plates of rutile structure with (100) or (001) face orientations. Microstructure, elemental-phase composition, and magnetic properties of the Fe-ion-implanted TiO₂ were studied by scanning and transmission electron microscopies (SEM and TEM), X-ray photoelectron (XPS) and Rutherford backscattering (RBS) spectroscopies, as well as vibrating-sample magnetometry (VSM). The high-fluence ion implantation results in the formation of magnetic nanoparticles of metallic iron beneath the irradiated surface of rutile. The induced ferromagnetism and observed two- or four-fold magnetic anisotropy are associated with the endotaxial growth of Fe nanoparticles oriented along the crystallographic axes of TiO₂. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2023–2024)

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17 pages, 15061 KiB

Open AccessArticle

Microstructure, Mechanical and Thermal Properties of Al/Cu/SiC Laminated Composites, Fabricated by the ARB and CARB Processes

by Jie Luo, Rashid Khattinejad, Amirhossein Assari, Moslem Tayyebi and Bejan Hamawandi

Crystals 2023, 13(2), 354; https://doi.org/10.3390/cryst13020354 - 18 Feb 2023

Cited by 11 | Viewed by 1563

Abstract

The aim of the current work is to investigate the effect of SiC particle weight percent and rolling passes on Al/Cu/SiC laminated composites, fabricated by accumulative roll-bonding (ARB) and cross-accumulative roll-bonding (CARB) processes. The optical microscopy (OM) images of composites revealed that despite [...] Read more.

The aim of the current work is to investigate the effect of SiC particle weight percent and rolling passes on Al/Cu/SiC laminated composites, fabricated by accumulative roll-bonding (ARB) and cross-accumulative roll-bonding (CARB) processes. The optical microscopy (OM) images of composites revealed that despite the good bonding of the layers, they underwent plastic instabilities as a consequence of strain hardening of the layers. However, these instabilities occurred more in ARBed composites than in composites fabricated by the CARB process. This is because in the latter process, the composites are rolled in two directions, which leads to better strain distribution. Furthermore, with an increase in passes, SiC particles were well distributed in the matrix and interfaces. The mechanical findings showed that, by increasing passes, there was a growth in the values of strengths and elongation. This behavior is believed to be related to increased work-hardening of layers, better distribution of reinforcing particles, and an enhanced bonding of interfaces at higher rolling passes. In addition, the results of thermal conductivities showed a downward trend with an increase in passes; in fact, the increased number of Al/Cu interfaces declined the heat conduction of composites. Full article

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15 pages, 13211 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Dependence of Charpy Impact Properties of Fe-30Mn-0.05C Steel on Microstructure

by Jianchao Xiong, Heng Li, Ling Kong, Xiaodan Zhang, Wenquan Cao and Yuhui Wang

Crystals 2023, 13(2), 353; https://doi.org/10.3390/cryst13020353 - 18 Feb 2023

Cited by 2 | Viewed by 1342

Abstract

Fe-30Mn-0.05C steel specimens with cold-rolled, partially recrystallized, fine-grained, and coarse-grained microstructures were fabricated by means of 80% cold rolling followed by annealing at 550–1000 °C. The initial and deformed microstructures were characterized, and the Charpy impact properties were tested at room temperature (RT) [...] Read more.

Fe-30Mn-0.05C steel specimens with cold-rolled, partially recrystallized, fine-grained, and coarse-grained microstructures were fabricated by means of 80% cold rolling followed by annealing at 550–1000 °C. The initial and deformed microstructures were characterized, and the Charpy impact properties were tested at room temperature (RT) and liquid nitrogen temperature (LNT). It was found that the Charpy absorbed energy increased with the annealing temperature, while the specimens showed different trends: parabolic increase at RT and exponential increase at LNT, respectively. Compared with the fully recrystallized specimens, those with a partially recrystallized microstructure exhibited lower impact energy, especially at LNT. This was because cracks tended to nucleate and propagate along the recovery microstructure where stress concentration existed. The grain size played an important role in the twinning behavior and impact properties. High Charpy impact energy (~320 J) was obtained in the coarse-grained specimen having the grain size of 42.1 μm at both RT and LNT, which was attributed to the activation of high-density deformation twinning. However, deformation twinning was inhibited in the specimen with the average grain size of 3.1 μm, resulting in limited work hardening and lower impact energy. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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12 pages, 2078 KiB

Open AccessFeature PaperArticle

Textile Functionalization by Porous Protein Crystal Conjugation and Guest Molecule Loading

by Luke F. Hartje, David A. Andales, Lucas P. Gintner, Lucas B. Johnson, Yan V. Li and Christopher D. Snow

Crystals 2023, 13(2), 352; https://doi.org/10.3390/cryst13020352 - 18 Feb 2023

Viewed by 1409

Abstract

Protein crystals are versatile nanostructured materials that can be readily engineered for applications in nanomedicine and nanobiotechnology. Despite their versatility, the small size of typical individual protein crystals (less than one cubic mm) presents challenges for macroscale applications. One way to overcome this [...] Read more.

Protein crystals are versatile nanostructured materials that can be readily engineered for applications in nanomedicine and nanobiotechnology. Despite their versatility, the small size of typical individual protein crystals (less than one cubic mm) presents challenges for macroscale applications. One way to overcome this limitation is by immobilizing protein crystals onto larger substrates. Cotton is composed primarily of cellulose, the most common natural fiber in the world, and is routinely used in numerous material applications including textiles, explosives, paper, and bookbinding. Here, two types of protein crystals were conjugated to the cellulosic substrate of cotton fabric using a 1,1′-carbonyldiimidazole/aldehyde mediated coupling protocol. The efficacy of this attachment was assessed via accelerated laundering and quantified by fluorescence imaging. The ability to load guest molecules of varying sizes into the scaffold structure of the conjugated protein crystals was also assessed. This work demonstrates the potential to create multifunctional textiles by incorporating diverse protein crystal scaffolds that can be infused with a multiplicity of useful guest molecules. Cargo molecule loading and release kinetics will depend on the size of the guest molecules as well as the protein crystal solvent channel geometry. Here, we demonstrate the loading of a small molecule dye into the small pores of hen egg white lysozyme crystals and a model enzyme into the 13-nm pores delimited by “CJ” crystals composed of an isoprenoid-binding protein from Campylerbacter jejuni. Full article

(This article belongs to the Special Issue Feature Papers in Biomolecular Crystals in 2022-2023)

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17 pages, 4408 KiB

Open AccessArticle

In Situ Observation of Retained Austenite Transformation in Low-Carbon Micro-Alloyed Q&P Steels

by Xiaoyu Ye, Haoqing Zheng, Gongting Zhang, Zhiyuan Chang, Zhiwang Zheng, Zhenyi Huang, Xiuhua Gao and Guanqiao Su

Crystals 2023, 13(2), 351; https://doi.org/10.3390/cryst13020351 - 18 Feb 2023

Cited by 3 | Viewed by 1374

Abstract

Retained austenite (RA) transformation and its role in the mechanical properties of three low-carbon micro-alloyed quenching and partitioning (Q&P) steels was investigated utilizing in situ tensile tests and electron microscopy. Meanwhile, RA’s strain-induced martensite transformation (SIMT) was analyzed and discussed in terms of [...] Read more.

Retained austenite (RA) transformation and its role in the mechanical properties of three low-carbon micro-alloyed quenching and partitioning (Q&P) steels was investigated utilizing in situ tensile tests and electron microscopy. Meanwhile, RA’s strain-induced martensite transformation (SIMT) was analyzed and discussed in terms of the strengthening mechanism. The results show that the ductility of the Q&P steels relies on the size and morphology of RA. In addition, both affect RA’s mechanical or thermostability. Dislocation density and carbon trapping should be considered in estimating the yield strength in the two-step Q&P process. V and Nb-Ti elements promote the formation of blocky RA. Ti accelerates the formation of film-like RA. For experimental Q&P steels with different processes and compositions, the true stress always keeps a linear relationship with the amount of transformed martensite, i.e., 30.38~46.37 MPa per vol. 1% transformed martensite, during the in situ tensile deformation. Full article

(This article belongs to the Special Issue Numerical Analysis of Microstructure and Mechanical Properties in Metallic Materials)

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3 pages, 168 KiB

Open AccessEditorial

Editorial on the Special Issue “Advances of Low-Dimensional Metal Halide Perovskite Materials”

by Binbin Luo, Ruosheng Zeng and Feiming Li

Crystals 2023, 13(2), 350; https://doi.org/10.3390/cryst13020350 - 18 Feb 2023

Viewed by 980

Abstract

Due to their outstanding performance in optoelectronic applications, lead-based halide perovskites (LHPs) have attained significant attention from scientists worldwide [...] Full article

(This article belongs to the Section Materials for Energy Applications)

2 pages, 159 KiB

Open AccessEditorial

Editorial for Special Issue “Frontiers of Semiconductor Lasers”

by Yongyi Chen and Li Qin

Crystals 2023, 13(2), 349; https://doi.org/10.3390/cryst13020349 - 18 Feb 2023

Viewed by 884

Abstract

Since the end of the last century, in which semiconductor lasers were fast developing, this kind of laser and its applications have greatly improved our world [...] Full article

(This article belongs to the Special Issue Frontiers of Semiconductor Lasers)

17 pages, 7306 KiB

Open AccessArticle

Effect of Mn⁺² Doping and Vacancy on the Ferromagnetic Cubic 3C-SiC Structure Using First Principles Calculations

by Najib M. Sultan, Thar M. Badri Albarody, Kingsley Onyebuchi Obodo and Masri B. Baharom

Crystals 2023, 13(2), 348; https://doi.org/10.3390/cryst13020348 - 17 Feb 2023

Cited by 1 | Viewed by 1640

Abstract

Wide bandgap semiconductors doped with transition metals are attracting significant attention in the fabrication of dilute magnetic semiconductor devices (DMSs). The working principle of DMSs is based on the manipulation of the electron spin, which is useful for magnetic memory devices and spintronic [...] Read more.

Wide bandgap semiconductors doped with transition metals are attracting significant attention in the fabrication of dilute magnetic semiconductor devices (DMSs). The working principle of DMSs is based on the manipulation of the electron spin, which is useful for magnetic memory devices and spintronic applications. Using the density functional theory (DFT) calculation with the GGA+U approximation, we investigated the effect of native defects on the magnetic and electronic structure of Mn+2-doped 3C-SiC structure. Three structures were selected with variations in the distance between two impurities of (Mn+2)-doped 3C-SiC, which are 4.364 Å, 5.345Å, and 6.171 Å, respectively. We found ferromagnetic coupling for single and double Mn+2 dopant atoms in the 3C-SiC structure with magnetic moments of 3

μ_{B}

and 6

μ_{B}

respectively. This is due to the double exchange because of p-d orbital hybridization. The p-orbitals of C atoms play important roles in the stability of the ferromagnetic configuration. The impact of Si-vacancy (nearby, far) and C-vacancy (near) of (Mn+2)-doped 3C-SiC plays an important role in the stabilization of AFM due to super-exchange coupling, while the C-vacancy (far) model is stable in FM. All electronic structures of Mn+2-doped 3C-SiC reveal a half-metallic behavior, except for the Si-vacancy and C-vacancy of (nearby), which shows a semiconductor with bandgap of 0.317 and 0.828 eV, respectively. The Curie temperature of (Mn+2)-doped 3C-SiC are all above room temperature. The study shows that native vacancies play a role in tuning the structure from (FM) to (AFM), and this finding is consistent with experiments reported in the literature. Full article

(This article belongs to the Special Issue First-Principles Simulation—Nano-Theory (Volume II))

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12 pages, 1774 KiB

Open AccessArticle

First-Principles Study of the Structural, Mechanical and Thermodynamic Properties of Al₁₁RE₃ in Aluminum Alloys

by Touwen Fan, Lan Lin, Houjiang Liang, Yuhong Ma, Yuwei Tang, Te Hu, Zixiong Ruan, Dongchu Chen and Yuanzhi Wu

Crystals 2023, 13(2), 347; https://doi.org/10.3390/cryst13020347 - 17 Feb 2023

Cited by 4 | Viewed by 1369

Abstract

The stability and mechanical and thermodynamic properties of Al₁₁RE₃ intermetallics (RE = Sc, Y and lanthanide La-Lu) have been investigated by combining first-principles and Debye model calculations. It was found that the formation enthalpies of the Al₁₁RE₃ [...] Read more.

The stability and mechanical and thermodynamic properties of Al₁₁RE₃ intermetallics (RE = Sc, Y and lanthanide La-Lu) have been investigated by combining first-principles and Debye model calculations. It was found that the formation enthalpies of the Al₁₁RE₃ intermetallics are all negative, indicating that they are stable; moreover, the experimental values of Al₁₁La₃ and Al₁₁Ce₃ are in good agreement with the predicted values, which are −0.40 kJ/mol and −0.38 kJ/mol, respectively. The calculated results of the mechanical properties reveal that the Young’s modulus E and shear modulus G of Al₁₁RE₃ (RE = La, Ce, Pr, Nd and Sm) intermetallics are obviously greater than that of Al, implying that the stiffness, toughness, and tensile strength of them are significantly greater than those of aluminum, and that they, as strengthen phases, can effectively improve the mechanical property of aluminum alloys. The Poisson’s ratio v of Al₁₁Sc₃ (0.37) is the largest, and the heterogeneity is obvious. All the Al₁₁RE₃ intermetallics can enhance the thermostability of the aluminum because of their lower Gibbs free energy F in the range of −5.002~−4.137 eV/atom and thermal expansion coefficient α of Al in the range of 2.34~2.89 × 10⁻⁵/K at 300K, as well as higher entropy and constant volume-specific heat than aluminum at finite temperatures. With an increase in the atomic number, different change trends were observed for the formation enthalpy ΔH_f, bulk modulus B, Young’s modulus E, and shear modulus G. This paper can provide ideas and help for designing a high-performance, heat-resistant aluminum alloy. Full article

(This article belongs to the Special Issue Advances in High Strength Steels)

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14 pages, 5024 KiB

Open AccessArticle

Synthesis, Supramolecular Structural Investigations of Co(II) and Cu(II) Azido Complexes with Pyridine-Type Ligands

by Mezna Saleh Altowyan, Jörg H. Albering, Assem Barakat, Saied M. Soliman and Morsy A. M. Abu-Youssef

Crystals 2023, 13(2), 346; https://doi.org/10.3390/cryst13020346 - 17 Feb 2023

Viewed by 887

Abstract

Two new Co(II) and Cu(II) azido complexes with 4-picoline (4-Pic) and pyridine-2-carboxaldoxime (HAld) were synthesized by self-assembly of the organic ligand and the M(II) nitrate in the presence of azide as a co-ligand. Their structures were determined to be [...] Read more.

Two new Co(II) and Cu(II) azido complexes with 4-picoline (4-Pic) and pyridine-2-carboxaldoxime (HAld) were synthesized by self-assembly of the organic ligand and the M(II) nitrate in the presence of azide as a co-ligand. Their structures were determined to be [Co(4-Pic)₄(H₂O)(N₃)]NO₃*H₂O*4-Pic (1) and [Cu(HAld)(Ald)(N₃)] (2) using X-ray single crystal diffraction. In complex 1, the coordination geometry is a slightly distorted octahedron with a water molecule and azide ion located trans to one another. On the other hand, complex 2 has a distorted square pyramid CuN₅ coordination sphere with N-atoms of the organic ligand as a basal plane and azide ion as apical. All types of intermolecular contacts and their contributions in the molecular packing were analyzed using Hirshfeld analysis. The intermolecular contacts, H…H (53.9%), O…H (14.1%), N…H (11.0%) and H…C (18.8%) in 1, and H…H (27.4%), N…H (27.7%), O…H (14.7%) and H…C (13.6%) in 2 have the largest contributions. Of all the contacts, the O…H, N…H and C…C interactions in 2 and the O…H, N…H and H…C in 1 are apparently shorter than the van der Waals radii sum of the interacting atoms. Atoms in molecules (AIM) topological parameters explained the lower symmetry of the coordinated azide in 1 than 2. Full article

(This article belongs to the Special Issue New Advances in Transition Metal Complexes)

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9 pages, 1831 KiB

Open AccessArticle

Influence of X Cation Covalence in the Formation of Ni-O-X Mixed Oxides by Reactive Ion Beam Mixing of Ni/X Interfaces

by Antonio Arranz and Carlos Palacio

Crystals 2023, 13(2), 345; https://doi.org/10.3390/cryst13020345 - 17 Feb 2023

Viewed by 985

Abstract

The reaction of the Ni/X interfaces (X = Si or Cr) with O₂⁺ ions at low energy (3 keV) was studied using X-ray photoelectron spectroscopy (XPS) and factor analysis (FA). It was found that low ion doses lead to the formation [...] Read more.

The reaction of the Ni/X interfaces (X = Si or Cr) with O₂⁺ ions at low energy (3 keV) was studied using X-ray photoelectron spectroscopy (XPS) and factor analysis (FA). It was found that low ion doses lead to the formation of a NiO thin film on the surface that was progressively transformed into a Ni-O-X mixed oxide with increasing the ion dose. The degree of transformation of NiO into Ni-O-X depended on the covalence of the X cation, indicating that the reaction was influenced by chemical driving forces. For strong covalent cations (Si and Al), NiO was completely transformed into Ni-O-X at ion doses above 1.8 × 10¹⁷ ions/cm², whereas for ionic cations (Cr) the transformation was incomplete. The ionicity of Ni atoms in the Ni-O-X mixed oxide increased with the increase in the covalence of X cation, and the features of the Ni 2p core level, characteristic of bulk NiO which were attributed to non-local screening, disappeared. Full article

(This article belongs to the Special Issue Research and Applications of Metal Oxide Thin Films)

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17 pages, 4692 KiB

Open AccessReview

Microstructural, Mechanical, and Corrosion Properties of AZXX Magnesium Alloy: A Review of Processing Methods

by Shalu Pargavi B., Todkar Utkarsh Dhanaji, Sejal Dassani, M. Somasundaram, A. Muthuchamy and A. Raja Annamalai

Crystals 2023, 13(2), 344; https://doi.org/10.3390/cryst13020344 - 17 Feb 2023

Cited by 3 | Viewed by 2591

Abstract

Magnesium (Mg) and its alloys are considered an ideal material for aerospace, medical, energy, and automotive purposes, because of their low density and high specific strength. Researchers are interested in AZ alloys because of their superior flow characteristics. This review makes an effort [...] Read more.

Magnesium (Mg) and its alloys are considered an ideal material for aerospace, medical, energy, and automotive purposes, because of their low density and high specific strength. Researchers are interested in AZ alloys because of their superior flow characteristics. This review makes an effort to summarise the numerous processing methods that have been adapted for use with AZXX alloy. One of the main obstacles to Mg alloys being used in their intended context is the difficulty of processing Mg and its alloys. Curiously, the homogenization process is often used in tandem with extrusion and rolling. It also gives an insight into the microstructure, mechanical (hardness, tensile, impact, fatigue, and creep), and electrochemical corrosion properties of AZXX alloys. The improvement of AZXX alloy can be attributed to the grain boundary strengthening and the second phase strengthening mechanisms. The effects of Al content and phases on properties are extensively discussed. This article summarises what has recently happened with AZXX wrought Mg alloy and offers some predictions for its future. Full article

(This article belongs to the Section Crystalline Metals and Alloys)

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15 pages, 4315 KiB

Open AccessArticle

Centrosymmetric Nickel(II) Complexes Derived from Bis-(Dithiocarbamato)piperazine with 1,1′-Bis-(Diphenylphosphino)ferrocene and 1,2-Bis-(Diphenylphosphino)ethane as Ancillary Ligands: Syntheses, Crystal Structure and Computational Studies

by Devyani Srivastava, Om Prakash, Gabriele Kociok-Köhn, Abhinav Kumar, Abdullah Alarifi, Naaser A. Y. Abduh, Mohd Afzal and Mohd Muddassir

Crystals 2023, 13(2), 343; https://doi.org/10.3390/cryst13020343 - 17 Feb 2023

Cited by 2 | Viewed by 1490

Abstract

Two Ni(II) complexes with the formula [{Ni(dppf)}₂{(L1)₂}](PF₆)₂ (Ni-I) and [{Ni(dppe)}₂{(L1)₂}](PF₆)₂ (Ni-II) were prepared by reacting [Ni(dppf)Cl₂] and [Ni(dppe)Cl₂] (dppf = 1,1′-Bis-(diphenylphosphino)ferrocene; dppe = 1,2-Bis-(diphenylphosphino)ethane) with [...] Read more.

Two Ni(II) complexes with the formula [{Ni(dppf)}₂{(L1)₂}](PF₆)₂ (Ni-I) and [{Ni(dppe)}₂{(L1)₂}](PF₆)₂ (Ni-II) were prepared by reacting [Ni(dppf)Cl₂] and [Ni(dppe)Cl₂] (dppf = 1,1′-Bis-(diphenylphosphino)ferrocene; dppe = 1,2-Bis-(diphenylphosphino)ethane) with secondary amine piperazine derived ligand disodium bis-(dithiocarbamate)piperazine ((piper(dtc)₂ = L1) and counter anion PF₆⁻. These complexes were characterized by elemental analyses, FT-IR, ¹H, ¹³C and ³¹P NMR, UV-Vis. spectroscopy and single crystal X-ray diffraction. The X-ray analyses reveal centrosymmetric structures where each Ni(II) centre adopts distorted square planar geometry defined by two sulfur centres of dithiocarbamate ligand and two phosphorus centres of dppf and dppe ligands in Ni-I and Ni-II, respectively. The supramolecular framework of both Ni-I and Ni-II are sustained by C-H⋯π and C-H⋯F interactions, and they also display interesting intramolecular C-H⋯Ni anagostic interactions. Further, the nature of these interactions are studied using Hirshfeld surface analyses, DFT and quantum theory of atoms in molecules (QTAIM) calculations. Additionally, non-covalent interaction (NCI) plot analyses were conducted to gain additional insight into these non-covalent interactions. This work is vital in a new approach towards the rational designing of the centrosymmetric molecules with interesting architectures. Full article

(This article belongs to the Special Issue Coordination Polymers: Design and Application)

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10 pages, 2778 KiB

Open AccessArticle

Hydrogen Bond-Directed Self-Assembly of a Novel Pyrene Derivative

by Yang Yu, Yuzhen Zhao, Yongsheng Mi, Fengmei Fang, Huimin Zhang, Zhun Guo, Yang Zhao and Dong Wang

Crystals 2023, 13(2), 342; https://doi.org/10.3390/cryst13020342 - 17 Feb 2023

Viewed by 1140

Abstract

A symmetrical pyrene derivative chemical structure was prepared by a classical synthetic method such as the Sonogashira cross-coupling reaction. The molecular structure of the product was characterised in detail by nuclear magnetic resonance (NMR), mass spectrometry (MS) and other methods. Furthermore, the optical [...] Read more.

A symmetrical pyrene derivative chemical structure was prepared by a classical synthetic method such as the Sonogashira cross-coupling reaction. The molecular structure of the product was characterised in detail by nuclear magnetic resonance (NMR), mass spectrometry (MS) and other methods. Furthermore, the optical properties of the novel products were studied by UV-vis and photoluminescence spectroscopy. The electrochemical properties of the molecules were fully characterised by comparison of electrochemical experiments and DFT simulation. Scanning electron microscope (SEM) observed that the product successfully formed a regular self-assembly structure. The product verifies the role of the molecular structure of the disc-mounted molecules on the optical and self-assembly properties, and is of reference value in the field of organic optoelectronic molecules Full article

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10 pages, 2843 KiB

Open AccessArticle

N-Heterocyclic Carbene–Palladium Functionalized Coordination Polymer (Pd-NHC@Eu-BCI) as an Efficient Heterogeneous Catalyst in the Suzuki–Miyaura Coupling Reaction

by Lixin You, Rui Tan, Xiaojuan Wang, Jianhong Hao, Shiyu Xie, Gang Xiong, Fu Ding, Andrei S. Potapov and Yaguang Sun

Crystals 2023, 13(2), 341; https://doi.org/10.3390/cryst13020341 - 17 Feb 2023

Cited by 1 | Viewed by 1335

Abstract

In the present work, a new heterogeneous catalyst Pd-NHC@Eu-BCI was synthesized by introducing N-heterocyclic carbene–palladium active sites into a 2D coordination polymer [Eu(BCI)(NO₃)₂H₂O]_n (Eu-BCI) based on a 1,3-bis(carboxymethyl)imidazolium (HBCI) ligand. The catalyst was characterized by various [...] Read more.

In the present work, a new heterogeneous catalyst Pd-NHC@Eu-BCI was synthesized by introducing N-heterocyclic carbene–palladium active sites into a 2D coordination polymer [Eu(BCI)(NO₃)₂H₂O]_n (Eu-BCI) based on a 1,3-bis(carboxymethyl)imidazolium (HBCI) ligand. The catalyst was characterized by various analytical techniques such as X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), infrared spectroscopy (IR) and thermogravimetric analysis (TGA). Catalytic activity of Pd-NHC@Eu-BCI was tested for the Suzuki–Miyaura cross-coupling reaction. The catalyst from the reaction mixture was easily recovered by filtration and still exhibited good catalytic activity and maintained its original structure after five cycles. Full article

(This article belongs to the Special Issue Multifunctional Coordination Polymers: Synthesis, Structure, Properties and Applications)

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18 pages, 3443 KiB

Open AccessArticle

The Fabrication of Gold–Silver Bimetallic Colloids by Microplasma: A Worthwhile Strategy for Counteracting the Surface Activity of Avian Influenza Virus

by Muhammad Zubair, Muhammad Shahid Rafique, Afshan Khalid, Tahir Yaqub, Muhammad Furqan Shahid, Suliman Yousef Alomar and Muhammad Ali Shar

Crystals 2023, 13(2), 340; https://doi.org/10.3390/cryst13020340 - 16 Feb 2023

Cited by 2 | Viewed by 1399

Abstract

In the present project, fructose-stabilized gold, silver and gold–silver bimetallic colloids have been synthesized by the electrochemical reduction of HAuCl₄·3H₂O (Au precursor) and AgNO₃ (Ag precursor), employing the atmospheric pressure microplasma technique. X-Ray Diffraction patterns of gold–silver bimetallic [...] Read more.

In the present project, fructose-stabilized gold, silver and gold–silver bimetallic colloids have been synthesized by the electrochemical reduction of HAuCl₄·3H₂O (Au precursor) and AgNO₃ (Ag precursor), employing the atmospheric pressure microplasma technique. X-Ray Diffraction patterns of gold–silver bimetallic particles exhibit (111), (200) and (220) planes identical to gold and silver NPs depicting FCC structures. The decrease in the peak intensities of Au–Ag (111) and Au–Ag (200) as compared to those of Au (111) and (200) is due to the formation of Au–Ag alloys. The FE-SEM image of gold–silver bimetallic NPs has revealed an adequate change in morphology as compared to the morphology of gold NPs and silver NPs. The majority of the gold–silver bimetallic NPs are spherical and are uniformly dispersed. The EDS spectra of (Au–Ag) confirm the presence of metallic gold and silver. The appearance of a single Surface Plasmon Resonance (SPR) peak in the UV–VIS absorption spectra of gold–silver colloids and its position in between the SPR peaks of the UV–VIS absorption spectra of gold and silver colloids justify the formation of gold–silver bimetallic alloy particles. In DLS measurements, the size distribution of gold–silver bimetallic colloids carries a narrow range 55 to 117 nm as compared to the size distribution of gold and silver colloids. The compatibility of the sizes of these colloids and the influenza virus belonging to the Orthomyxoviruses family (size range 80–300 nm with different morphologies) are assumed to stand responsible for an effective bio-conjunction with Influenza viruses. Au–Ag bimetallic nanostructures have synergistically improved their antiviral activity against H9N2 influenza virus as compared to monometallic AuNPs and AgNPs. Thus, the Au–Ag nanostructured alliance has been proven to be more effective and is capable of manifesting high antiviral efficacy. Full article

(This article belongs to the Special Issue Nanomaterials for Potential Applications)

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13 pages, 3763 KiB

Open AccessArticle

Study on the Chromogenic Mechanism of Violet-Red to Orange-Red Spinel

by Yang Du and Ying Guo

Crystals 2023, 13(2), 339; https://doi.org/10.3390/cryst13020339 - 16 Feb 2023

Viewed by 1493

Abstract

In this paper, the chemical composition and spectroscopy of 38 violet-red to orange-red spinel samples were analyzed by energy dispersive X-ray fluorescence spectrometer and UV-visible spectrophotometer, based on CIE LAB color space, to explore the effects of different chromogenic ions on spinel color [...] Read more.

In this paper, the chemical composition and spectroscopy of 38 violet-red to orange-red spinel samples were analyzed by energy dispersive X-ray fluorescence spectrometer and UV-visible spectrophotometer, based on CIE LAB color space, to explore the effects of different chromogenic ions on spinel color transition. The results show that the chroma C* is mainly controlled by the variation of color coordinates a*, and the hue angle h° is mainly controlled by the variation of color coordinates b*. Spinel can be divided into iron-bearing spinel and chromium–vanadium-bearing spinel according to their chromogenic elements, where Fe is mostly present in the form of Fe²⁺, which is mainly replaced with Mg²⁺ in tetrahedral voids, while Cr³⁺ and V³⁺ are mainly replaced with Al³⁺ in octahedral voids, and the level of Al content indicates the degree of isomorphism in spinel. The lightness L* of spinel decreases with increasing Cr content, and the hue h° decreases with increasing Fe and increases with increasing V content. Full article

(This article belongs to the Topic In-Situ Study of Mineralogy, Gemology and Progress in Gemology)
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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4 pages, 187 KiB

Open AccessEditorial

Novel ZnO-Based Nanostructures: Synthesis, Characterization and Applications

by Yamin Leprince-Wang, Guangyin Jing and Basma El Zein

Crystals 2023, 13(2), 338; https://doi.org/10.3390/cryst13020338 - 16 Feb 2023

Viewed by 1282

Abstract

The Special Issue “Novel ZnO-Based Nanostructures: Synthesis, Characterization and Applications” is a collection of 13 papers, including 3 review papers and 10 original articles dedicated to both experimental research works and numerical simulations on ZnO nanostructures [...] Full article

(This article belongs to the Special Issue Novel ZnO-Based Nanostructures: Synthesis, Characterization and Applications)

12 pages, 5982 KiB

Open AccessArticle

Chirality as a Feature of the Crystal Structure of Lanthanide Ion Complexes—Some Simple Examples

by Lioubov I. Semenova, Irene Ling and Alexandre N. Sobolev

Crystals 2023, 13(2), 337; https://doi.org/10.3390/cryst13020337 - 16 Feb 2023

Viewed by 1262

Abstract

Single-crystal X-ray structure determinations are reported for four lanthanide complexes, [Dy(bipy)₂Cl₂(OH₂)₂]Cl^.H₂O (bipy = 2,2′-bipyridine), 1; [La₂(phen)₂(O₂CCH₃)₄(NO₃)₂] [...] Read more.

Single-crystal X-ray structure determinations are reported for four lanthanide complexes, [Dy(bipy)₂Cl₂(OH₂)₂]Cl^.H₂O (bipy = 2,2′-bipyridine), 1; [La₂(phen)₂(O₂CCH₃)₄(NO₃)₂] (phen = 1,10-phenanthroline), 2; [Lu(terpy)(O₂CCH₃)₃]^.NaNO₃ (terpy = 2,2′;6′,2″-terpyridine) 3; and [Lu(phen)(O₂CH)₃(OH₂)]^.H₂O, 4. Dispersion interactions within the stacked arrays of coordinated aza-aromatic units found in all four complexes appear to be a significant structural influence in the solid state. For complex 1, there are additional interactions beyond dispersion, which suggests that it may be the means whereby the Δ and Λ forms contribute to the overall chiral nature of the crystal. These weak intermolecular interactions were investigated in detail using the Hirshfeld surface analysis. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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