Research

32 pages, 4173 KiB

Open AccessArticle

Insight into Adsorption Kinetics of Cs⁺, Rb⁺, Co²⁺, and Sr²⁺ on a Zeolites-Based Composite: Comprehensive Diffusional Explanation and Modelling

by Abdel Boughriet, Gildas Doyemet, Nicole Poumaye, Oscar Allahdin and Michel Wartel

Appl. Sci. 2024, 14(8), 3511; https://doi.org/10.3390/app14083511 - 22 Apr 2024

Viewed by 336

Abstract

Kaolinite-rich soils were used to prepare zeolite-based composites via alkaline activation. The porous material was characterized by conducting XRD and microporosity measurements, as well as ESEM microscopy. The Weber and Morris (W-M) model was used for studying adsorption kinetics of radioactive cations on [...] Read more.

Kaolinite-rich soils were used to prepare zeolite-based composites via alkaline activation. The porous material was characterized by conducting XRD and microporosity measurements, as well as ESEM microscopy. The Weber and Morris (W-M) model was used for studying adsorption kinetics of radioactive cations on synthesized alkali-activated material. These investigations evidenced the effects of pore structure and the importance of the intrinsic characteristics of hydrated cations (ionic potential; hydrated radius; B-viscosity parameter; molar Gibbs energy of hydration of cation) on W-M kinetic rate constants. The application of diffusion-based models permitted us to assess the key diffusion parameters controlling successive diffusion regimes, and to reveal strong contributions of surface diffusion to adsorption kinetics during the course of the second and third kinetics stages of the W-M model. The magnitude of the surface diffusion coefficient was related to the capacity of hydrated cationic species to lose water molecules when penetrating brick pores. The HSDM model were tested for predicting radionuclide adsorption in a fixed-bed column. A breakthrough curve simulation indicated the predominance of the surface diffusion regime, which was in agreement with mathematical analysis of (batch) adsorption kinetics data. Ionic diffusion was linked to the characteristics of capillary porosity and connectivity of capillary pores in the composite, suggesting the generation of hydrated nuclides and their immobilization in the form of outer-sphere complexes. Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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11 pages, 3193 KiB

Open AccessArticle

Revealing the Impact of Ga and Y Doping on Thermal and Electrical Behavior of LaMnO₃ Ceramic Materials

by Paulina Vlazan, Catalin Nicolae Marin, Iosif Malaescu, Gabriela Vlase, Titus Vlase, Maria Poienar and Paula Sfirloaga

Appl. Sci. 2024, 14(4), 1546; https://doi.org/10.3390/app14041546 - 15 Feb 2024

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Abstract

The synthesis, thermal behavior and electrical properties of a series of undoped and 1% Ga- or Y-doped lanthanum manganite compounds, obtained via the sol–gel technique, are reported. Scanning electron microscopy (SEM/EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analyses were performed [...] Read more.

The synthesis, thermal behavior and electrical properties of a series of undoped and 1% Ga- or Y-doped lanthanum manganite compounds, obtained via the sol–gel technique, are reported. Scanning electron microscopy (SEM/EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analyses were performed on all synthesized samples. The XRD results confirmed a good crystallinity for all studied samples, and a change in the crystal structure of Ga- or Y-doped lanthanum manganite (Pm-3m space group) was observed compared to the pristine sample (R-3c space group). Thermal analysis highlighted a different behavior of the doped samples compared to the undoped sample, observed by the different mass losses in the analyzed temperature range. For these materials, it is shown for the first time that the static electrical conductivity, σ_DC, of Ga- or Y-doped LaMnO₃ compounds increases compared to the σ_DC of the pristine sample, and the thermal activation energy of the process of electrical conduction, E_A,cond, increases linearly with the temperature for all three studied samples. Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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18 pages, 6690 KiB

Open AccessArticle

Characterization of an Active Soldering Zn-Mg Alloy and the Study of Ultrasonic Soldering of SiC Ceramics with Copper Substrate

by Roman Kolenak, Alexej Pluhar, Jaromir Drapala, Peter Gogola, Matej Pasak and Mikulas Sloboda

Appl. Sci. 2024, 14(4), 1504; https://doi.org/10.3390/app14041504 - 13 Feb 2024

Viewed by 558

Abstract

The aim of this study was to characterize a Zn-Mg type soldering alloy and direct soldering of SiC ceramics with a copper substrate. The Zn1.5Mg solder exerts a wider melting interval. The temperature of the eutectic reaction was 365 °C, and the liquidus [...] Read more.

The aim of this study was to characterize a Zn-Mg type soldering alloy and direct soldering of SiC ceramics with a copper substrate. The Zn1.5Mg solder exerts a wider melting interval. The temperature of the eutectic reaction was 365 °C, and the liquidus temperature was 405 °C. The microstructure of the soldering alloy is comprised of a zinc matrix. Segregation of binary eutectics in the form of (Zn) + Mg₂Zn₁₁ lamellas occurred on the boundaries of Zn grains. Additionally, the presence of a MgZn₂ magnesium phase was observed in the solder matrix. The SiC/solder bond was formed due to magnesium distribution from solder to the boundary with SiC ceramics, where magnesium reacts with silicon, which is infiltered in SiC ceramics. By a mutual interaction, a new Mg₂Si phase is formed. An interaction between the molten zinc solder and Cu substrate occurred on the boundary of the Cu/substrate joint at the formation of a transition zone composed of two new phases, namely the γCu (Cu₅Zn₈) non-wettable phase type, approximately 30 µm wide, and a wettable (CuZn₄) phase type ε, approximately 12 µm wide. The average shear strength of a combined SiC/Cu joint fabricated using Zn1.5Mg solder was 44 MPa. Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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14 pages, 4720 KiB

Open AccessArticle

New PVP–Ag or Pd-Doped Perovskite Oxide Hybrid Structures for Water Splitting Electrocatalysis

by Adina Căta, Bogdan-Ovidiu Țăranu, Ioana Maria Carmen Ienașcu and Paula Sfirloaga

Appl. Sci. 2024, 14(3), 1186; https://doi.org/10.3390/app14031186 - 31 Jan 2024

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Abstract

Global warming and the global energy crisis are two major challenges humanity is currently confronting that are pressuring the scientific community to find efficient, low-cost, and environmentally sustainable solutions. Within this context, hydrogen has emerged as a clean and efficient energy carrier promising [...] Read more.

Global warming and the global energy crisis are two major challenges humanity is currently confronting that are pressuring the scientific community to find efficient, low-cost, and environmentally sustainable solutions. Within this context, hydrogen has emerged as a clean and efficient energy carrier promising to replace environmentally hazardous fossil fuels. The present study, of relevance to the water splitting domain, concerns the synthesis of two novel hybrid structures, namely polyvinylpyrrolidone (PVP) functionalized with Ag-doped LaMnO₃ and Pd-doped LaMnO₃, respectively. The water electrolysis catalytic activity of these new materials was evaluated in a strongly alkaline medium. Perovskite-based modified electrodes were manufactured through four different procedures. The samples displayed electrocatalytic activity for the O₂ evolution reaction and the most active electrode was the one obtained by drop-casting a mixture of LaMnO₃:Ag/PVP and Carbon Black on graphite support. The study is aimed at and succeeds in increasing the scientific database concerning the role of perovskite oxides in the water-splitting field. Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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22 pages, 5455 KiB

Open AccessArticle

Antibacterial and In Vitro Bioactivity Studies of Silver-Doped, Cerium-Doped, and Silver–Cerium Co-Doped 80S Mesoporous Bioactive Glass Particles via Spray Pyrolysis

by Mannie Belay Taye, Henni Setia Ningsih and Shao-Ju Shih

Appl. Sci. 2023, 13(23), 12637; https://doi.org/10.3390/app132312637 - 24 Nov 2023

Cited by 4 | Viewed by 1132

Abstract

Researchers are concentrating on discovering reducing treatments for bacterial infections due to the worrisome and quick rise of drug-resistant microbial-related illnesses. Metallic ion doping and co-doping mesoporous bioactive glass (MBG) can defend against drug-resistant pathogens of Escherichia coli (E. coli) infection [...] Read more.

Researchers are concentrating on discovering reducing treatments for bacterial infections due to the worrisome and quick rise of drug-resistant microbial-related illnesses. Metallic ion doping and co-doping mesoporous bioactive glass (MBG) can defend against drug-resistant pathogens of Escherichia coli (E. coli) infection of wounds and solve the issues of bone deformities. In this study, un-doped MBG, silver-doped MBG (Ag-doped MBG), cerium-doped MBG (Ce-doped MBG), and silver–cerium co-doped MBG (Ag-Ce co-doped MBG) have been successfully synthesized via the spray pyrolysis method. In addition, various characterization techniques, including X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption–desorption, were used to investigate the phase compositions, surface morphologies, chemical compositions, inner structure morphologies, chemical bonds/functional groups, and specific surface areas, respectively. The antibacterial efficacy against E. coli was assessed using the colony count technique. All types of MBG with Ag, Ce, and Ag-Ce were effective against E. coli. Furthermore, when immersed in simulated body fluid, the MBGs formed hydroxyapatite and could be used to improve bone defects. Only 5.75 mol% Ag-doped MBG showed toxicity in the MTT assay test. According to our analysis, the 80S-Ag-Ce-MBG was the first Ag-Ce co-doped MBG. Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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12 pages, 7778 KiB

Open AccessArticle

Electrophysical Properties of PZT-Type Ceramics Obtained by Two Sintering Methods

by Przemysław Niemiec, Dariusz Bochenek and Grzegorz Dercz

Appl. Sci. 2023, 13(20), 11195; https://doi.org/10.3390/app132011195 - 12 Oct 2023

Viewed by 1034

Abstract

This study demonstrates the impact of two sintering techniques on the fundamental properties of doped PZT-type ceramic materials (with Mn⁴⁺, Sb³⁺, Gd³⁺, and W⁶⁺), with the general chemical formula Pb(Zr_0.49Ti_0.51)_0.94 [...] Read more.

This study demonstrates the impact of two sintering techniques on the fundamental properties of doped PZT-type ceramic materials (with Mn⁴⁺, Sb³⁺, Gd³⁺, and W⁶⁺), with the general chemical formula Pb(Zr_0.49Ti_0.51)_0.94Mn_0.021Sb_0.016Gd_0.012W_0.012O₃. The synthesis of ceramic powders was carried out through the calcination method. Two different methods were used in the final sintering process: (i) pressureless sintering (PS) and (ii) hot pressing (HP). The PZT-type ceramics were subjected to electrophysical measurements, encompassing various analyses such as X-ray diffraction (XRD), microstructure (scanning electron microscopy (SEM)), ferroelectric and dielectric properties, and DC electrical conductivity. The analysis of the crystal structure at room temperature showed that the material belongs to the perovskite structure from the tetragonal phase (P4mm space group) without foreign phases. Both sintering methods ensure obtaining the material with appropriate dielectric and ferroelectric parameters, and the tests carried out verified that the ceramic materials have a diverse range of parameters appropriate for use in micromechatronic and microelectronic applications. The obtained ceramic material has high permittivity values, low dielectric loss tangent values, and high resistance. At room temperature, the ceramic samples’ P-E hysteresis loops do not saturate at a field of 3.5 kV/mm (P_m maximum polarization is in the range from 12.24 to 13.47 μC/cm²). However, at higher temperatures, the P-E hysteresis loops become highly saturated, and, at 110 °C, the P_m maximum polarization values are in the range from 28.02 to 30.83 μC/cm². Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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11 pages, 1355 KiB

Open AccessArticle

Application of the Lock-In Technique in Magnetoelectric Coupling Measurements of the PZT/Terfenol-D Composite

by Jakub Grotel, Tomasz Pikula and Rafał Mech

Appl. Sci. 2023, 13(17), 9543; https://doi.org/10.3390/app13179543 - 23 Aug 2023

Cited by 1 | Viewed by 994

Abstract

This paper presents a study of magnetoelectric (ME) properties of the PZT/Terfenol-D composite with a varying number of layers. The composite consists of piezoelectric and magnetostrictive phases that are mechanically coupled. The purpose of this setup is to gain control over the electric [...] Read more.

This paper presents a study of magnetoelectric (ME) properties of the PZT/Terfenol-D composite with a varying number of layers. The composite consists of piezoelectric and magnetostrictive phases that are mechanically coupled. The purpose of this setup is to gain control over the electric polarization of a material via an external magnetic field. Unlike most similar composites, our samples utilize a commercial piezoelectric patch instead of pure PZT. At present, researchers face two main problems regarding magnetoelectric materials: (i) the effect is observed far below room temperature for single-phase materials, and (ii) the ME coupling is too weak to be commercially viable. Our research was carried out via the lock-in technique on two PZT/Terfenol-D samples we synthesized. Relatively strong room-temperature magnetoelectric coupling between piezoelectric and magnetostrictive phases was observed for both samples. Two types of characteristics were investigated: (i) ME voltage versus magnetic AC field frequency, and (ii) ME voltage versus magnetic DC field. We detected multiple, grouped signal peaks ascribed to different resonance modes. Uniquely, the peaks form band-like characteristics which might be an important step in bringing the materials closer to wider commercial use. Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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15 pages, 8026 KiB

Open AccessArticle

Dielectric Spectroscopy Studies and Modelling of Piezoelectric Properties of Multiferroic Ceramics

by Agata Lisińska-Czekaj, Dionizy Czekaj, Barbara Garbarz-Glos, Wojciech Bąk, Temesgen Tadeyos Zate and Jae-Ho Jeon

Appl. Sci. 2023, 13(12), 7193; https://doi.org/10.3390/app13127193 - 16 Jun 2023

Viewed by 1073

Abstract

Compounds and solid solutions of bismuth ferrite (BiFeO₃)—barium titanate (BaTiO₃) system are of great scientific and engineering interest as multiferroic and potential high-temperature lead-free piezoelectric materials. In the present paper, the results of research on the synthesis and characterisation [...] Read more.

Compounds and solid solutions of bismuth ferrite (BiFeO₃)—barium titanate (BaTiO₃) system are of great scientific and engineering interest as multiferroic and potential high-temperature lead-free piezoelectric materials. In the present paper, the results of research on the synthesis and characterisation of 0.67Bi₁.₀₂FeO₃–0.33BaTiO₃ (67BFBT) ceramics in terms of crystal structure and dielectric and piezoelectric properties are reported. It was found that the produced 67BFBT ceramics were characterised by a tetragonal crystal structure described by the P4mm space group, an average crystallite size <D> ≈ 80 nm, and an average strain <ε> = 0.01%. Broad-band dielectric spectroscopy (BBDS) was employed to characterise the dielectric response of polycrystalline ceramics. The frequency range from ν = 10⁻¹ Hz to ν = 10⁵ Hz was used to characterise the influence of the electric field strength on dielectric response of the ceramic sample at room temperature. The dielectric spectra were checked for consistency with the Kramers–Kronig test, and the high quality of the measurements were confirmed. The electric equivalent circuit method was used to fit the dielectric spectra within the frequency range that corresponded to the occurrence of the resonant spectra of the radial mode for thin disk sample, i.e., from ν = 10⁵ Hz to ν = 10⁷ Hz and the temperature range from T = −20 °C to T = 50 °C. The electric equivalent circuit [R_sCPE₁([L₁R₁C₁]C₀)] was used, and good fitting quality was reached. The relevant calculations were performed, and it was found that the piezoelectric charge coefficient exhibited a value of d₃₁ = 35 pC/N and the planar coupling factor was k_p = 31% at room temperature. Analysis of impedance spectra performed in terms of circumferential magnetic field made it possible to establish an influence of magnetic field on piezoelectric parameters of 67BFBT multiferroic ceramics. Additionally, the “magnetic” tunability of the modulus of the complex dielectric permittivity makes 67BFBT a sensing material with vast potential. Full article

(This article belongs to the Special Issue Novel Ceramic Materials: Processes, Properties and Applications)

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