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Crystals, Volume 15, Issue 2 (February 2025) – 68 articles

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16 pages, 2603 KiB  
Article
Photodegradation of Amoxicillin Under UV Irradiation Using Hydrogen Peroxide
by Isam Y. Qudsieh, Mohammad Ashraf Ali and Ibrahim M. Maafa
Crystals 2025, 15(2), 167; https://doi.org/10.3390/cryst15020167 (registering DOI) - 9 Feb 2025
Viewed by 59
Abstract
This experiment investigated the degradation of amoxicillin in water using hydrogen peroxide (H2O2) and UV Irradiation. The parameters analyzed included the initial concentration of amoxicillin, the pH of the solution, and the quantity of H2O2 used. [...] Read more.
This experiment investigated the degradation of amoxicillin in water using hydrogen peroxide (H2O2) and UV Irradiation. The parameters analyzed included the initial concentration of amoxicillin, the pH of the solution, and the quantity of H2O2 used. These factors were examined to assess the effectiveness of the photodegradation process. No degradation of amoxicillin was observed in the dark during stirring for 20 min. The investigation demonstrated successful photodegradation of amoxicillin using H2O2 as an oxidant in the presence of UV Irradiation. The pH of the irradiated solution significantly influenced the degradation of amoxicillin, with minimal degradation at acidic pH and a gradual increase as the pH shifted towards more basic conditions. Degradation was more pronounced with higher concentrations of H2O2, while it decreased as the concentration of amoxicillin in the reacting solution increased. Complete degradation was achieved using 3 mL of H2O2. The experimental data were well-fitted to zero-order reaction kinetics. The findings of this investigation show significant improvements compared to previously reported results in the field of photocatalysis using nanomaterials and photolysis techniques involving UV and H2O2. The novelty of our research is in the different experimental parameters used for the UV/H2O2 photolysis process, which distinguishes it from other previous investigations. The UV/H2O2 system proved highly effective in the photodegradation of amoxicillin, making it a viable option for degrading other organic pollutants commonly found in industrial wastewater. Full article
(This article belongs to the Special Issue Research and Application of Photoelectrocatalytic Materials)
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22 pages, 8587 KiB  
Article
Regulating the Mechanical and Corrosion Properties of Mg-2Zn-0.1Y Alloy by Trace SiC with Different Morphologies
by Furong Guo, Kaibo Nie, Kunkun Deng and Yanan Li
Crystals 2025, 15(2), 166; https://doi.org/10.3390/cryst15020166 (registering DOI) - 8 Feb 2025
Viewed by 133
Abstract
Traditional magnesium structural materials are used widely due to their light weight; however, their corrosion resistance is poor. In order to address this problem and improve the strength simultaneously, SiCp-, SiCnp-, and SiCnw-reinforced Mg-2Zn-0.1Y (wt. %, MZY alloy) matrix composites (SiC/MZY composites) with [...] Read more.
Traditional magnesium structural materials are used widely due to their light weight; however, their corrosion resistance is poor. In order to address this problem and improve the strength simultaneously, SiCp-, SiCnp-, and SiCnw-reinforced Mg-2Zn-0.1Y (wt. %, MZY alloy) matrix composites (SiC/MZY composites) with the same contents (0.3 wt. %) were prepared and extruded at low temperature in this paper. The effects of SiC morphology on the microstructure, mechanical properties and corrosion resistance of MZY alloy were studied. The results show that the grain size can be refined by adding SiC reinforcement. Compared with the unreinforced MZY alloy, the strengths of the SiC/MZY composites were all improved, with a yield strength of more than 440 MPa and an ultimate tensile strength of more than 450 MPa. However, only the corrosion rate of the composites reinforced by submicron SiCp was improved significantly. The hydrogen evolution corrosion rate (PH) was reduced by 81% relative to the MZY alloy. This can be attributed to the decreased galvanic corrosion pairs, as well as the decreased potential difference between the second phase and the matrix in the SiCp/MZY composite. Additionally, a compact product film on the surface of the SiCp/MZY composite can also protect the matrix. The materials prepared in this study showed excellent strength and high corrosion resistance at relatively low cost, providing valuable insights and design ideas for the development and application of those materials in marine and offshore engineering applications. Full article
(This article belongs to the Special Issue Microstructure and Mechanical Properties of Alloys and Composites)
12 pages, 29110 KiB  
Article
Study on Pitting Behavior of Welding Joint of Bimetal Composite Pipes in Suspended Sulfur Solution
by Yuwei Sun, Sirong Yu, Bingying Wang, Lin Liu, Enyang Liu and Tao Feng
Crystals 2025, 15(2), 165; https://doi.org/10.3390/cryst15020165 (registering DOI) - 8 Feb 2025
Viewed by 121
Abstract
Due to the severe corrosion environment, corrosion problems caused by sulfur deposition are one important reason for the failure of composite pipes in the long-term service process when Incoloy825/X65 bimetallic composite pipes are used in high-sulfur oil and gas transportation. In this paper, [...] Read more.
Due to the severe corrosion environment, corrosion problems caused by sulfur deposition are one important reason for the failure of composite pipes in the long-term service process when Incoloy825/X65 bimetallic composite pipes are used in high-sulfur oil and gas transportation. In this paper, an Incoloy825/X65 bimetallic composite pipe was subjected to an immersion corrosion test in suspended sulfur solution to observe the corrosion morphology and characterize the corrosion products using a SEM, EDS, and XRD. The adsorption behavior of the Incoloy825 alloy in terms of sulfur elements was investigated. The results show that the heat-affected zone (HAZ) of the welding joint is the preferred region for pitting corrosion. The film of corrosion product on the Incoloy825 was mainly composed of NiS, FeS, and Cr2S3, and its thickness was 7–13 μm. With prolongation of the immersion time, the pitting resistance of the surface product film of nickel-based alloys is weakened and then enhanced, and the corrosion product film can act as a barrier to anion transfer and inhibit the occurrence of pitting. Full article
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25 pages, 2947 KiB  
Review
Progress in Plastic Work–Heat Conversion of Metallic Crystals
by Peng-Fei Yue, Shao-Dan Yang, Yan Gao, Rong-Hao Shi, Guo-Shang Zhang, Zhi-Yuan Zhu, Dong Han and Ke-Xing Song
Crystals 2025, 15(2), 164; https://doi.org/10.3390/cryst15020164 (registering DOI) - 8 Feb 2025
Viewed by 104
Abstract
The Taylor–Quinney coefficient (TQC) is a critical parameter quantifying the thermal conversion of plastic work during deformation in metallic crystals. This review provides a comprehensive summary of recent advances in TQC research, spanning experimental, theoretical, and computational perspectives. The fundamental principles of the [...] Read more.
The Taylor–Quinney coefficient (TQC) is a critical parameter quantifying the thermal conversion of plastic work during deformation in metallic crystals. This review provides a comprehensive summary of recent advances in TQC research, spanning experimental, theoretical, and computational perspectives. The fundamental principles of the TQC are introduced, emphasizing its thermodynamic background and dependence on microstructural features. Experimental studies demonstrate how the strain rate, temperature, and microstructure influence the TQC, with advanced techniques such as infrared thermography and high-speed imaging enabling precise measurements under dynamic conditions. Theoretical models, including internal variable frameworks and nonequilibrium thermodynamics, offer insights into the energy distribution mechanisms and provide predictive capabilities across diverse loading scenarios. Computational simulations, using methods like finite element analysis and molecular dynamics, reveal multiscale thermal conversion mechanisms and the role of dislocation motion and localized heat accumulation in governing TQC values. Challenges and opportunities for TQC research are highlighted, including the need for multiscale modeling, the exploration of complex stress states, and applications under extreme environments. Future directions should focus on integrating advanced experimental techniques and computational models to optimize material design and performance. This review aims to deepen the understanding of the TQC and its implications for energy dissipation and material reliability in high-performance applications. Full article
15 pages, 8707 KiB  
Article
Constraint Effect on Tensile and Fatigue Fracture of Coach Peel Specimens of Novel Aluminum–Steel Resistance Spot Welds
by Liting Shi and Xiangcheng Guo
Crystals 2025, 15(2), 163; https://doi.org/10.3390/cryst15020163 (registering DOI) - 8 Feb 2025
Viewed by 172
Abstract
In response to the growing demand for fuel economy and the imperative to reduce greenhouse gas emissions, the automotive industry has embraced structural lightweighting through multi-material solutions. This poses challenges in joining dissimilar lightweight metals, such as aluminum alloys to steels. The effects [...] Read more.
In response to the growing demand for fuel economy and the imperative to reduce greenhouse gas emissions, the automotive industry has embraced structural lightweighting through multi-material solutions. This poses challenges in joining dissimilar lightweight metals, such as aluminum alloys to steels. The effects of the diameter of a weld nugget have been well documented, particularly in relation to its effects on the tensile strength, tensile fracture modes and fatigue behavior. For tensile shear specimens, various methods have been developed over the years to predict fracture modes by deriving the critical nugget diameter. However, these methods have proved inadequate for coach peel specimens, where a noteworthy observation is the occurrence of pull-out fracture modes with smaller weld nugget diameters than the critical diameter. In the present study, aluminum alloy sheets and steel sheets were resistance spot welded, achieving a deliberately reduced weld nugget diameter to induce an interfacial fracture mode in the tensile testing of coach peel specimens. Intriguingly, it was noted that fatigue fracture modes in the same coach peel specimens transitioned from pull-out to interfacial with decreasing applied loads, challenging conventional expectations. Furthermore, finite element analysis was performed, and the findings indicated that the fracture modes of the coach peel specimens were influenced not only by the diameter of the weld nugget but also by local stress states, specifically the stress triaxiality at the tips of the spot weld notches. Full article
(This article belongs to the Special Issue Fatigue and Fracture of Welded Structures)
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15 pages, 3403 KiB  
Review
A Chemical Transport Method for the Synthesis of Simple and Complex Inorganic Crystals—Survey of Applications and Modeling
by Grzegorz Matyszczak, Krzysztof Krawczyk, Albert Yedzikhanau and Michał Brzozowski
Crystals 2025, 15(2), 162; https://doi.org/10.3390/cryst15020162 (registering DOI) - 8 Feb 2025
Viewed by 159
Abstract
The chemical transport method is a process that occurs naturally; however, it is also very useful in the chemical laboratory environment for the synthesis of inorganic crystals. It was successfully used for the syntheses of simple and complex inorganic compounds, from binary (e.g., [...] Read more.
The chemical transport method is a process that occurs naturally; however, it is also very useful in the chemical laboratory environment for the synthesis of inorganic crystals. It was successfully used for the syntheses of simple and complex inorganic compounds, from binary (e.g., ZnS, CdSe) to quaternary (e.g., Cu2ZnSnS4) compounds. Many experimental parameters influence the quality of products of chemical transport reactions, and among them, one may distinguish the used precursors and applied temperature gradient. The careful selection of experimental conditions is crucial for the production of high-quality crystals. Mathematical descriptions of the chemical transport phenomena, however, may potentially help in the design of proper conditions. Full article
(This article belongs to the Special Issue Solidification and Crystallization of Inorganic Materials)
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15 pages, 3338 KiB  
Article
One-Pot Strategies for Lithium Recovery from Beta-Spodumene and LTA-Type Zeolite Synthesis
by Leonardo Leandro dos Santos, Rubens Maribondo do Nascimento and Sibele Berenice Castellã Pergher
Crystals 2025, 15(2), 161; https://doi.org/10.3390/cryst15020161 (registering DOI) - 8 Feb 2025
Viewed by 177
Abstract
This study presents a groundbreaking method for extracting lithium from beta-spodumene while simultaneously achieving the sustainable synthesis of LTA-type zeolite, designated as LPM-15, without relying on organic solvents or calcination. Lithium extraction was efficiently performed using sodium salts, accompanied by the recycling of [...] Read more.
This study presents a groundbreaking method for extracting lithium from beta-spodumene while simultaneously achieving the sustainable synthesis of LTA-type zeolite, designated as LPM-15, without relying on organic solvents or calcination. Lithium extraction was efficiently performed using sodium salts, accompanied by the recycling of the mother liquor, with lithium content in the supernatant precisely quantified via atomic absorption spectroscopy (AAS). The optimized synthesis route enables the concurrent production of Li2CO3 and LPM-15, distinguished by a powdered appearance without a well-defined geometric framework and a unique cubic morphology with spherical facets, respectively. To gain deeper insights into the process, density functional theory (DFT) simulations were conducted to analyze how different cation exchanges (Na+ replacing Al3+, NH4+ replacing Al3+, and Ca2+ replacing Al3+) influence the structural stability and diffusion dynamics within the zeolitic pores of LPM-15. Additionally, cation-exchange capacity (CEC) measurements further assessed ion mobility within the LPM-15 framework. This integrative approach not only sheds light on the fundamental mechanisms underpinning LTA-type zeolite synthesis but also demonstrates their versatile applications, with particular emphasis on water purification technologies. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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19 pages, 7066 KiB  
Article
First-Principles Study of Mechanical Properties of Pb(ZrxTi1−x)O3 in the Cubic and Tetragonal Phase
by Xudong Ran, Shaolan Zhou, Shaowen Zhou, Wei Lei, Lin Xiang, Yang Wu, Bingfei Hu, Jianquan Tao and Qiang Chen
Crystals 2025, 15(2), 160; https://doi.org/10.3390/cryst15020160 - 5 Feb 2025
Viewed by 305
Abstract
In this study, we employed the first-principles method based on density functional theory to calculate the elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and density of states for both cubic and tetragonal phases of Pb(ZrxTi1−x)O3 [...] Read more.
In this study, we employed the first-principles method based on density functional theory to calculate the elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and density of states for both cubic and tetragonal phases of Pb(ZrxTi1−x)O3. The structural model of Pb(ZrxTi1−x)O3 was established using the virtual crystal approximation (VCA). Our results demonstrate that the VCA-calculated properties are in excellent agreement with other theoretical predictions and experimental data. As the Zr content increases, the lattice constants of both cubic and tetragonal Pb(ZrxTi1−x)O3 increase, while the c/a ratio initially decreases and subsequently increases. Both cubic and tetragonal Pb(ZrxTi1−x)O3 satisfy the Born stability criteria, indicating mechanical stability. For the cubic phase, the elastic constants, bulk modulus, and shear modulus decrease with increasing Zr content. In contrast, for the tetragonal phase, the elastic and shear moduli exhibit a non-monotonic trend, peaking at a Zr content of 0.5, where Pb(Zr0.5Ti0.5)O3 demonstrates superior mechanical properties. A comparative analysis reveals that as Zr content increases, the cubic phase exhibits enhanced structural resilience, greater electronic structure stability, and increased anisotropy. These characteristics make cubic Pb(ZrxTi1−x)O3 more suitable for advanced manufacturing techniques such as additive manufacturing, offering enhanced design flexibility for ferroelectric materials. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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10 pages, 4617 KiB  
Article
Aerosol Deposited Polycrystalline PbZr0.53Ti0.47O3 Thick Films with a Large Transverse Piezoelectric Coefficient
by Long Teng, Juan Yang, Yongguang Xiao, Hongbo Cheng, Shibo Gong, Gao Luo, Jinlin Yang, Wenjia Zhang, Zhenwei Shen and Jun Ouyang
Crystals 2025, 15(2), 159; https://doi.org/10.3390/cryst15020159 - 5 Feb 2025
Viewed by 324
Abstract
The aerosol deposition (AD) method utilizes high kinetic-energy submicron powders to impact and form a film on a substrate. It is a highly efficient deposition method, capable of producing films or coatings with a strong interfacial bonding and a dense nano-grain structure without [...] Read more.
The aerosol deposition (AD) method utilizes high kinetic-energy submicron powders to impact and form a film on a substrate. It is a highly efficient deposition method, capable of producing films or coatings with a strong interfacial bonding and a dense nano-grain structure without thermal assistance. In this work, PbZr0.53Ti0.47O3 (PZT53/47) films (~1.2 μm thick) were deposited on Pt/Ti/Si(100) substrates via the AD method. After a conventional annealing process (700 °C for 1 h), these PZT53/47 films displayed a dense, crack-free, nano-grained morphology, corresponding to an optimal electrical performance. A large maximum polarization (Pmax = 70 μC/cm2) and a small coercive field (Ec = 104 kV/cm) were achieved under the maximum applicable electric field of 1.6 MV/cm. The PZT53/47 films also exhibited a large small-field dielectric constant of ~984, a high tunability of 72%, and a low leakage current of ~3.1 × 10−5 A/cm2 @ 40 V. Moreover, the transverse piezoelectric coefficient (e31.f) of these AD-processed films was as high as −4.6 C/m2, comparable to those of sputter-deposited PZT53/47 films. These high-quality PZT53/47 thick films have broad applications in piezoelectric micro-electromechanical systems. Full article
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13 pages, 2281 KiB  
Article
Innovative Hygroscopic Material for Humidity Regulation: Diatomaceous Earth Composite Porous Ceramic
by Zhennan Yao, Enza Migliore, Massimiliano Galluzzi and Jingze Liu
Crystals 2025, 15(2), 158; https://doi.org/10.3390/cryst15020158 - 4 Feb 2025
Viewed by 406
Abstract
Urbanization in hot and humid regions such as southern China has increased the demand for comfortable indoor environments. In order to design a material for efficient passive indoor humidity regulation, this study investigates a composite material that combines the hygroscopic properties of salt [...] Read more.
Urbanization in hot and humid regions such as southern China has increased the demand for comfortable indoor environments. In order to design a material for efficient passive indoor humidity regulation, this study investigates a composite material that combines the hygroscopic properties of salt and the adsorption capacity of diatomaceous earth (DE). Firstly, we prepared DE and boehmite into moisture-absorbing porous materials. Then, the initial DE-based sample was innovatively doped with SiO2 nanomaterials and loaded with LiCl to enhance the humidity regulation ability of the composite, especially in the adsorption and desorption ability of water vapour. The microstructure and phase composition of the composite samples were analysed, and we observed an increase in porosity, filling performance and capillary condensation upon the introduction of SiO2 nanoparticles. The hygroscopic salt loaded into the pores can absorb more water when exposed to the ambient humidity. This synergic effect can effectively improve the hygroscopic performance of the composite material while maintaining the stability of the physical and chemical properties. The optimized samples showed a moisture absorption rate of 28% in high-humidity environments, meeting moisture buffer value evaluation standards. The study’s findings lay the foundation for the future integration of these materials through advanced manufacturing technologies. Full article
(This article belongs to the Section Polycrystalline Ceramics)
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33 pages, 53588 KiB  
Article
Unraveling the Determinant Mechanisms in Flow-Mediated Crystal Growth and Phase Behaviors
by L. Connor Willis, Tesia D. Janicki, Rekha R. Rao and Z. Leonardo Liu
Crystals 2025, 15(2), 157; https://doi.org/10.3390/cryst15020157 - 4 Feb 2025
Viewed by 414
Abstract
To uncover the critical mechanisms responsible for mesoscopic level development during flow-mediated crystal growth, we develop a semi-two-way hydrodynamic coupled structural phase-field crystal formalism (HXPFC-s2). The new formalism, inspired by previous attempts at coupling hydrodynamic and phase-field crystal (PFC) equations, allows for studying [...] Read more.
To uncover the critical mechanisms responsible for mesoscopic level development during flow-mediated crystal growth, we develop a semi-two-way hydrodynamic coupled structural phase-field crystal formalism (HXPFC-s2). The new formalism, inspired by previous attempts at coupling hydrodynamic and phase-field crystal (PFC) equations, allows for studying mesoscopic flow-mediated crystallization at diffusive timescales pertinent to industrial applications. Unlike previous efforts, the devised coupling to the structural PFC (XPFC) equations allows generalization to more complex crystal structures through explicit parameterization of the direct correlation function (DCF). Utilizing the HXPFC-s2 formalism, we seek to uncover the determinant physical mechanisms in crystallization under simple shear flows by comparing temperature-driven crystallization to flow-mediated crystallization under varying flow-strengths. Parallels and deviations of under-cooling and flow-strength effects on crystal growth are drawn using the crystal cluster-size and system ordering time evolutions. In doing so, we identify scaling behaviors with a Peclet-like number, Pe˜, a critical Peclet-like number, Pe˜*, and flow-field-crystal plane-dependent interactions. Our findings may be relevant for controlling crystal growth and phase behaviors in flow applications. Full article
(This article belongs to the Special Issue Crystallization Process and Simulation Calculation, Third Edition)
15 pages, 4738 KiB  
Article
Estimation of Hardness of Single-Phase Metallic Alloys
by Ottó K. Temesi, Nguyen Q. Chinh, Levente Vitos and Lajos K. Varga
Crystals 2025, 15(2), 156; https://doi.org/10.3390/cryst15020156 - 2 Feb 2025
Viewed by 446
Abstract
First, we discuss a common feature of single-phase pure metals and amorphous and high-entropy alloys: the maximum value of hardness corresponding to a valence electron count (VEC) value of around 6.5–7. This correlation is explained by the coincidence that by subtracting the number [...] Read more.
First, we discuss a common feature of single-phase pure metals and amorphous and high-entropy alloys: the maximum value of hardness corresponding to a valence electron count (VEC) value of around 6.5–7. This correlation is explained by the coincidence that by subtracting the number of sp valence electrons (Nsp = 2) from the VEC we obtain the maximal number of unpaired d electrons, Nd = 4.5–5 in the 3d, 4d, and 5d rows of transition elements. These unpaired d electrons form orbital overlap bonding, which is stronger than the isotropic metallic bonds of a delocalized electron cloud. The more unpaired d electrons there are, the higher the bonding strength. Second, we will discuss the hardness formulas derived from cohesion energy and shear modulus. We will demonstrate that both types of formulas originate in the electrostatic energy density of metallic bonds, expressing a 1/R4 dependence. Finally, we show that only two parameters are sufficient to estimate hardness: the atomic radius and the cohesion-based valence. In the case of alloys, our formula gives a lower bound on the hardness only. It is not suitable for calculation of the hardness increase caused by solid solution, grain size, precipitation, and phase mixture. Full article
(This article belongs to the Special Issue Microstructure and Deformation of Advanced Alloys)
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22 pages, 8797 KiB  
Article
Distortion and Residual Stress Reduction Using Asynchronous Heating Sources for Multi-Robot Coordinated Wire-Arc Directed Energy Deposition
by Yongzhe Li, Chenxiao Zhang, Caowei Huang, Xiaoyu Wang, Guangjun Zhang and Yijun Zhou
Crystals 2025, 15(2), 155; https://doi.org/10.3390/cryst15020155 - 2 Feb 2025
Viewed by 423
Abstract
Multi-robot coordinated wire-arc directed energy deposition (MRC-WA-DED) has proliferated in recent decades, employing asynchronous independent heating sources to deposit material simultaneously. Beyond enhancing efficiency, MRC-WA-DED introduces a synergic effect between the heating sources, resulting in a controllable thermal field on the deposit component. [...] Read more.
Multi-robot coordinated wire-arc directed energy deposition (MRC-WA-DED) has proliferated in recent decades, employing asynchronous independent heating sources to deposit material simultaneously. Beyond enhancing efficiency, MRC-WA-DED introduces a synergic effect between the heating sources, resulting in a controllable thermal field on the deposit component. This research aims to investigate if the synergic effect is beneficial for residual stress and distortion reduction and how it can be applied to enhance the quality of MRC-WA-DEDed parts. A finite element model was developed to compare the thermodynamic response of WA-DED when both coordinated heating sources (CHSs) and a single heating source (SHS) are applied. Simulation and deposition experiments were carried out to clarify the influence of different coordination strategies on the fabricated component’s thermal behavior, stress distribution, and distortion conditions. The results indicate that the synergic effect of CHSs leads to a smoother temperature gradient than that accomplished by a SHS, reducing the maximum distortion of a single layer by 49.1%. As validated by actual depositions, the residual stress, maximum distortion, and hardness of a ten-layer component were reduced by 6.5%, 11.2%, and 18.6%, respectively. Full article
(This article belongs to the Special Issue Advanced Welding and Additive Manufacturing)
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18 pages, 4654 KiB  
Article
The Effect of Different Laser Powers on the Properties of Ni65A Cladding Reinforced by WC
by Mengqiong Huang, Jincheng Yu, Jinyi Wang, Guilin Xu and Xin Jin
Crystals 2025, 15(2), 154; https://doi.org/10.3390/cryst15020154 - 2 Feb 2025
Viewed by 362
Abstract
In this paper, the effects of different laser powers on the microstructure, microhardness, and wear resistance of Ni65A/WC composite coatings were investigated by using laser cladding technology. The morphology, phase structure, elemental distribution, wear behaviour, and property changes of the fused coatings were [...] Read more.
In this paper, the effects of different laser powers on the microstructure, microhardness, and wear resistance of Ni65A/WC composite coatings were investigated by using laser cladding technology. The morphology, phase structure, elemental distribution, wear behaviour, and property changes of the fused coatings were systematically characterised and analysed. The mechanism of power parameters on coating properties was summarised. The results show that different laser powers significantly affect the microstructure of the coating and the distribution of the enhanced phase WC. Under the 800 W power condition, the WC particles were not sufficiently dissolved and the organisation was not dense. The hardness and abrasion resistance were low. Under 1200 W power conditions, the enhanced phases were uniformly dispersed. The best microstructure densities and homogeneity were observed. The generated hard phase and matrix toughness achieved a good balance. The hardness of the coating reached 375 HV while also showing optimum wear resistance and stable friction behaviour. Under 1600 W power conditions, although the hard phase was completely dissolved and re-precipitated, some areas of tissue coarsening made the wear resistance slightly inferior to that at 1200 W. The 2000 W power condition resulted in a significant deterioration in the coating properties due to the increase in cracks and pores caused by the overheating of the melt pool. For this reason, 1200 W power conditions proved to be the ideal parameter range for optimising the microstructure and mechanical properties of Ni65A/WC composite coatings. The study in this paper can provide an important reference for the design of high-performance wear-resistant coatings. Full article
(This article belongs to the Special Issue Recent Trends in Laser Cladding and Surface Alloying)
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20 pages, 7604 KiB  
Article
Copper-Substituted Calcium Orthophosphate (CaxCu1-x)HPO4.nH2O for Humidity Detection
by Yurii Milovanov, Mehran Dadkhah, Ahmed Sabry Afify and Jean-Marc Tulliani
Crystals 2025, 15(2), 153; https://doi.org/10.3390/cryst15020153 - 1 Feb 2025
Viewed by 398
Abstract
Calcium orthophosphate material (Ca1-xCux)HPO4.nH2O (0.4 ≤ x ≤ 1) with the gradual replacement of Ca2+ with Cu2+ ions were synthesized by a chemical precipitation technique. Samples were characterized by X-ray diffraction (XRD), scanning [...] Read more.
Calcium orthophosphate material (Ca1-xCux)HPO4.nH2O (0.4 ≤ x ≤ 1) with the gradual replacement of Ca2+ with Cu2+ ions were synthesized by a chemical precipitation technique. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Then, the prepared powders were deposited onto an alumina substrate with interdigitated Pt electrodes by the spin coating method and polyvinyl alcohol (PVA) as a binder. Successively, the sensors were investigated from 0% to 90% at room temperature under various conditions, including humidity, nitrogenous oxide, methane, carbon dioxide and ammonia. The results evidenced that at 90% RH, the sensitivity of sensors significantly increased with the increase in the Cu content. Moreover, the sensors exhibited good repeatability and, after 1 year of aging, the sensor response was equal to 34% that of the freshly prepared sensor. Finally, there was no interference in the presence of other gases (nitrogenous oxide 2.5 ppm, methane 10 ppm, carbon dioxide 500 ppm and ammonia 4 ppm). Full article
(This article belongs to the Special Issue Celebrating the 10th Anniversary of International Crystallography)
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15 pages, 3550 KiB  
Article
Enhancing Perovskite Solar Cell Stability by TCO Layer Presence Beneath MACl-Doped Perovskites
by Minkyu Song, Jinyoung Kim and Gyu Min Kim
Crystals 2025, 15(2), 152; https://doi.org/10.3390/cryst15020152 - 1 Feb 2025
Viewed by 452
Abstract
Perovskite solar cells (PSCs) have emerged as a promising photovoltaic technology, yet their stability under environmental stressors remains a critical challenge. This study examines the substrate-dependent degradation mechanisms of perovskite films and evaluates the role of methylammonium chloride (MACl) incorporation. Devices fabricated on [...] Read more.
Perovskite solar cells (PSCs) have emerged as a promising photovoltaic technology, yet their stability under environmental stressors remains a critical challenge. This study examines the substrate-dependent degradation mechanisms of perovskite films and evaluates the role of methylammonium chloride (MACl) incorporation. Devices fabricated on ITO and glass substrates exhibited markedly different stability behaviors under high-humidity conditions. ITO substrates delayed the phase transition from the black α-phase to the yellow δ-phase due to stronger substrate–film interactions and reduced defect densities, while glass substrates facilitated rapid degradation through moisture infiltration and grain boundary instability. MACl incorporation enhanced the initial crystallinity and optoelectronic properties of the perovskite films, as evidenced by superior power conversion efficiency and photon absorption. However, residual MACl under humid conditions introduced structural instability, particularly on glass substrates. To address these challenges, a fully coated ITO structure, referred to as the Island Type design, was proposed. This structure eliminates exposed glass regions, leveraging the stabilizing properties of ITO to suppress moisture infiltration and prolong device durability. The findings provide a comprehensive understanding of the interplay between substrate properties and material composition in PSC stability and highlight the potential of structural optimizations to balance efficiency and durability for commercial applications. Full article
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14 pages, 3993 KiB  
Article
Mineralogical Characteristics and Color Origin of Nephrite Containing Pink Minerals
by Ye Yuan, Youxuan Li and Miao Shi
Crystals 2025, 15(2), 151; https://doi.org/10.3390/cryst15020151 - 1 Feb 2025
Viewed by 362
Abstract
Recently, a variety of nephrite containing localized pink mineral aggregates has emerged on the market, which is sometimes referred to as “peach blossom jade” by some merchants. Currently, there is limited research on this type of nephrite containing pink minerals, and its detailed [...] Read more.
Recently, a variety of nephrite containing localized pink mineral aggregates has emerged on the market, which is sometimes referred to as “peach blossom jade” by some merchants. Currently, there is limited research on this type of nephrite containing pink minerals, and its detailed mineral composition characteristics and coloration mechanisms remain unclear. In this study, four samples of nephrite containing pink minerals were systematically investigated using conventional gemological tests, as well as modern analytical techniques such as X-ray powder diffraction (XRD), infrared spectroscopy (IR), laser Raman spectroscopy, ultraviolet–visible (UV-Vis) absorption spectroscopy, electron probe microanalysis (EPMA), and X-ray fluorescence spectroscopy (XRF). These techniques were employed to elucidate the mineral composition, chemical composition, spectroscopic features, and coloration origins of the samples. The results indicate that the primary mineral constituent of the samples is tremolite, with accessory minerals including zoisite, muscovite, orthoclase, andesine, diopside, and prehnite. The major chemical components of the samples are SiO2, CaO, and MgO, along with minor amounts of Al2O3, K2O, and FeOT. The overall green hue of the samples is positively correlated with Fe content. The pink mineral present in the samples is predominantly Mn-bearing zoisite, and the pink coloration of zoisite is primarily attributed to the energy level transitions of Mn2+ at approximately 540 nm and 440 nm. Full article
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)
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13 pages, 2934 KiB  
Article
Nonlinear Optical Bistability in a Bragg Reflector Multilayered Structure with MoS2
by Songqing Tang, Xilei Dong, Leyong Jiang, Haishao Chen, Zhuoya Sun, Fuping Zhang, Yangbin Zhu and Yunyang Ye
Crystals 2025, 15(2), 150; https://doi.org/10.3390/cryst15020150 - 31 Jan 2025
Viewed by 372
Abstract
The special band structure of bilayer MoS2 makes it show strong nonlinear optical characteristics in the visible band, which provides a new way to develop visible nonlinear devices. In this paper, we present a theoretical analysis of the optical bistability (OB) in [...] Read more.
The special band structure of bilayer MoS2 makes it show strong nonlinear optical characteristics in the visible band, which provides a new way to develop visible nonlinear devices. In this paper, we present a theoretical analysis of the optical bistability (OB) in a silver–Bragg reflector structure by embedding bilayer MoS2 at the visible band. The nonlinear OB phenomenon is achieved due to the nonlinear conductivity of the bilayer MoS2 and the excitation of the optical Tamm state at the interface between the silver and the Bragg reflector. It is found that the hysteresis behavior and the threshold width of the OB can be effectively tuned by varying the incident light wavelength. In addition, the optical bistable behavior of the structure can be adjusted by varying the position of the MoS2 inset in the defect layer, the incident angle, and the structural parameters of the spacer layer. We believe the above results can provide a new paradigm for the construction of controllable bistable devices. Full article
(This article belongs to the Special Issue Advances of Nonlinear Optical Materials)
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20 pages, 8855 KiB  
Article
Additive Manufacturing of High-Performance Ti-Mo Alloys Used on a Puncture Needle: The Role of Linear Energy Density in Microstructure Evolution and Mechanical Properties
by Xuesong Dai, Yue Sun and Jitai Han
Crystals 2025, 15(2), 149; https://doi.org/10.3390/cryst15020149 - 31 Jan 2025
Viewed by 376
Abstract
This study involved the preparation of dense Ti-10wt.%Mo alloys using selective laser melting (SLM) with a powder combination of pure titanium (Ti) and pure molybdenum (Mo). Integrating temperature stress numerical simulations and actual data elucidates the correlation between linear laser energy density and [...] Read more.
This study involved the preparation of dense Ti-10wt.%Mo alloys using selective laser melting (SLM) with a powder combination of pure titanium (Ti) and pure molybdenum (Mo). Integrating temperature stress numerical simulations and actual data elucidates the correlation between linear laser energy density and residual stress. The impact of linear energy density on the surface roughness, densification behavior, microstructural development, and mechanical properties of SLM-processed Ti-10Mo components was also examined. As linear energy density diminished from 0.125 J/mm to 0.233 J/mm, surface roughness reduced from 18.2 μm to 4.4 μm, while relative compactness increased from 94.9% to 99.8%, respectively. It is necessary to reduce the friction between the puncture needle or implant needle and human tissue, enhancing comfort and precision. The microstructural investigation revealed that SLM-processed Ti-10Mo alloys consist of a phase combination of hexagonal tight-packed (hcp) α-Ti and body-centered cubic (bcc) β-Ti, with heterogeneous conchoidal microstructures found in the samples. Furthermore, as the laser energy input increased, Mo powder particles were mostly fully melted, leading to a significant rise in the microhardness value. The as-built Ti-10Mo alloys exhibited a high ultimate tensile strength of 860 MPa and an elongation of 32.9% at a linear laser energy density of 0.15 J/mm, with the fracture morphology indicating a mixed fracture mode mostly characterized by ductile fracture. This research can enhance the prospective bio-application of Ti-Mo alloys. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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20 pages, 16771 KiB  
Article
A Comparison of the Hot Deformation Behavior and Constitutive Model of the GH4079 Alloy
by Weifeng Ying, Jia Hou, Shengnan Jiang and Jianan Wang
Crystals 2025, 15(2), 148; https://doi.org/10.3390/cryst15020148 - 31 Jan 2025
Viewed by 336
Abstract
In this paper, GH4079 alloy was thermally compressed under processing conditions of 1025 °C–1200 °C and 0.001 s−1–1 s−1. This article established the strain compensation Arrhenius constitutive equation, the improved Johnson–Cook constitutive equation, and the strain compensation Arrhenius constitutive [...] Read more.
In this paper, GH4079 alloy was thermally compressed under processing conditions of 1025 °C–1200 °C and 0.001 s−1–1 s−1. This article established the strain compensation Arrhenius constitutive equation, the improved Johnson–Cook constitutive equation, and the strain compensation Arrhenius constitutive model based on phase transition temperature segmentation and calculated the correlation coefficient (R) and local relative error (AARE) to verify the accuracy of the model, respectively. Finally, a certain microstructural analysis was combined. It can be concluded that the rheological stress of alloy GH4079 gradually decreases with the increase in temperature and strain rate. The AARE values of these three models are 21.09%, 20.47%, and 10.62%, respectively. The strain compensation Arrhenius model based on phase transition temperature segments can better describe the thermal deformation behavior of GH4079. By integrating this model, appropriate processing conditions can be selected to regulate the microstructural organization and achieve optimization during the practical application of the alloy. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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6 pages, 170 KiB  
Editorial
Crystallization of High-Performance Metallic Materials
by Wangzhong Mu and Chao Chen
Crystals 2025, 15(2), 147; https://doi.org/10.3390/cryst15020147 - 30 Jan 2025
Viewed by 351
Abstract
Crystallization includes liquid/solid and solid/solid phase transitions, important processes for improving engineering material performance, which have attracted significant attention in the community. The current Special Issue (SI) entitled ‘Crystallization of High-Performance Metallic Materials’ has collected twelve research papers focusing on different [...] Read more.
Crystallization includes liquid/solid and solid/solid phase transitions, important processes for improving engineering material performance, which have attracted significant attention in the community. The current Special Issue (SI) entitled ‘Crystallization of High-Performance Metallic Materials’ has collected twelve research papers focusing on different aspects of the crystallization of metallic materials, e.g., the solidification of steel, fatigue and fracture behaviors of magnesium composites, nucleation of intermetallic compounds in aluminum alloys, microstructure evolution in nickel-based super-alloys, etc. The summary of crystallization behaviors at different temperature ranges in different metallic materials contributes to the state of the art of engineering material development. Full article
(This article belongs to the Special Issue Crystallization of High Performance Metallic Materials)
28 pages, 10098 KiB  
Review
A Short Review of Advancements in Additive Manufacturing of Cemented Carbides
by Zhe Zhao, Xiaonan Ni, Zijian Hu, Wenxin Yang, Xin Deng, Shanghua Wu, Yanhui Li, Guanglin Nie, Haidong Wu, Jinyang Liu and Yong Huang
Crystals 2025, 15(2), 146; https://doi.org/10.3390/cryst15020146 - 30 Jan 2025
Viewed by 453
Abstract
Cemented carbides, renowned for their exceptional strength, hardness, elastic modulus, wear resistance, corrosion resistance, low coefficient of thermal expansion, and chemical stability, have long been indispensable tooling materials in metal cutting, oil drilling, and engineering excavation. The advent of additive manufacturing (AM), commonly [...] Read more.
Cemented carbides, renowned for their exceptional strength, hardness, elastic modulus, wear resistance, corrosion resistance, low coefficient of thermal expansion, and chemical stability, have long been indispensable tooling materials in metal cutting, oil drilling, and engineering excavation. The advent of additive manufacturing (AM), commonly known as “3D printing”, has sparked considerable interest in the processing of cemented carbides. Among the various AM techniques, Selective Laser Melting (SLM), Selective Laser Sintering (SLS), Selective Electron Beam Melting (SEBM), and Binder Jetting Additive Manufacturing (BJAM) have garnered frequent attention. Despite the great application potential of AM, no single AM technique has been universally adopted for the large-scale production of cemented carbides yet. The SLM and SEBM processes confront substantial challenges, such as a non-uniform sintering temperature field, which often result in uneven sintering and frequent post-solidification cracking. SLS notably struggles with achieving a high relative density of carbides. While BJAM yields WC-Co samples with a lower incidence of cracking, it is not without flaws, including abnormal WC grain growth, coarse WC clustering, Co-rich pool formation, and porosity. Three-dimensional gel-printing, though possessing certain advantages from its sintering performance, falls short in dimensional and geometric precision control, as well as fabrication efficiency. Cemented carbides produced via AM processes have yet to match the quality of their traditionally prepared counterparts. To date, the specific densification and microstructure evolution mechanisms during the AM process, and their interrelationship with the feedstock carbide material design, printing/sintering process, and resulting mechanical behavior, have not been thoroughly investigated. This gap in our knowledge impedes the rapid advancement of AM for carbide processing. This article offers a succinct overview of additive manufacturing of cemented carbides, complemented by an analysis of the current research landscape. It highlights the benefits and inherent challenges of these techniques, aiming to provide clarity on the present state of the AM processing of cemented carbides and to offer insights into potential future research directions and technological advancements. Full article
(This article belongs to the Special Issue High-Performance Metallic Materials)
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12 pages, 4780 KiB  
Article
Mathematical Modeling to Predict the Formation of Micrometer-Scale Crystals Using Reverse Anti-Solvent Crystallization
by Jianhua Wang, Fawei Wang, Xu Wen, Yankang Zhang, Jiapeng Wang and Yucun Liu
Crystals 2025, 15(2), 145; https://doi.org/10.3390/cryst15020145 - 29 Jan 2025
Viewed by 501
Abstract
The reverse addition process in anti-solvent crystallization is safer and more efficient than sieving when dealing with energetic compounds. A new mathematical model has been developed to understand the crystal size mechanism during the reverse addition of solvent in a binary system. This [...] Read more.
The reverse addition process in anti-solvent crystallization is safer and more efficient than sieving when dealing with energetic compounds. A new mathematical model has been developed to understand the crystal size mechanism during the reverse addition of solvent in a binary system. This model incorporates droplet dynamics, distribution moments, and mass balance constraints. It can be used to predict the appropriate crystal size for designing explosive recipes with a desired particle size distribution to maximize energy output. The model was validated by conducting reverse-addition crystallization of sodium chloride in a deionized water/ethanol binary system at temperatures ranging from 10 to 50 degrees Celsius. The predicted results closely matched the experimental findings, which were confirmed using a Laser Particle Size Analyzer and Electron Microscope Scanning. Full article
(This article belongs to the Special Issue Crystallization Process and Simulation Calculation, Third Edition)
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18 pages, 8358 KiB  
Article
Corrosion Behavior and Mechanism of High-Aluminum Inconel 625 in Chlorinated Salts
by Ying Wei, Junjia Cao, Yuehong Zheng, Haicun Yu, Penghui Yang and Peiqing La
Crystals 2025, 15(2), 144; https://doi.org/10.3390/cryst15020144 - 29 Jan 2025
Viewed by 491
Abstract
Concentrated solar power plant (CSP) technology holds significant application value in the renewable energy sector for converting solar radiation into thermal and electrical energy. As a heat storage medium for next-generation solar thermal power stations, chloride salts exhibit strong corrosive effects on structural [...] Read more.
Concentrated solar power plant (CSP) technology holds significant application value in the renewable energy sector for converting solar radiation into thermal and electrical energy. As a heat storage medium for next-generation solar thermal power stations, chloride salts exhibit strong corrosive effects on structural components. To enhance corrosion resistance of the heated body in molten salt environments, Inconel 625 is modified by incorporating aluminum, which facilitates the formation of a protective oxide film. In this study, High-Aluminum Inconel 625, after cold rolling and solution treatment, was immersed in a NaCl-KCl-MgCl2 eutectic chloride melt at 650 °C for 200 h. Post-corrosion analysis revealed the formation of an alumina layer on the surface, effectively mitigating corrosion. Increased aluminum content resulted in thicker alumina layers and the formation of oxidation products, such as Cr2O3, Fe2O3, MoO2, and MgCr2O4 spinel structures, significantly enhancing the alloy’s corrosion resistance. The Inconel 625 cold-rolled plate with 5.31 wt% Al exhibited the best corrosion resistance (3510 μm/year), making it a promising candidate for use in next-generation CSP heat storage and exchange components. Full article
(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)
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19 pages, 8425 KiB  
Article
Spectroscopic Ellipsometry and Wave Optics: A Dual Approach to Characterizing TiN/AlN Composite Dielectrics
by Mohamed El Hachemi, Nikhar Khanna and Emanuele Barborini
Crystals 2025, 15(2), 143; https://doi.org/10.3390/cryst15020143 - 29 Jan 2025
Viewed by 361
Abstract
In this paper, we present a method for retrieving the optical properties of a nano-designed TiN/AlN composite dielectric, using spectroscopic ellipsometry for experimental measurements and wave optics simulations for numerical analysis. Composite cermets have gained attention for solar–thermal energy conversion, but [...] Read more.
In this paper, we present a method for retrieving the optical properties of a nano-designed TiN/AlN composite dielectric, using spectroscopic ellipsometry for experimental measurements and wave optics simulations for numerical analysis. Composite cermets have gained attention for solar–thermal energy conversion, but their fundamental optical properties are not well understood. While characterizing uniformly deposited layers is generally straightforward, the process becomes more complex for nanoparticulate composites. The refractive index is essential for investigating and tuning the optical characteristics of the composite. Our method employs COMSOL Multiphysics software, validated by experimental spectroscopic ellipsometry studies. The strong agreement between experimental and numerical results supports this approach as a rational way to design material models for optical property studies across a broad spectrum. Full article
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16 pages, 35462 KiB  
Article
Research on the Microstructure and Properties of Arc-Sprayed Austenitic Stainless Steel and Nickel-Based Alloy Composite Coatings with Different Spraying Distances
by Jingang Yan, Zhenming Yang, Limin Zhang and Jianxin Wang
Crystals 2025, 15(2), 142; https://doi.org/10.3390/cryst15020142 - 28 Jan 2025
Viewed by 370
Abstract
1Cr18Ni9Ti and Monel composite metal coatings with five different spraying distances were prepared by arc spraying technology. The density, hardness, friction, and wear properties and acid corrosion rate of the coatings with different spraying distances were studied by X-ray diffraction, scanning electron microscopy, [...] Read more.
1Cr18Ni9Ti and Monel composite metal coatings with five different spraying distances were prepared by arc spraying technology. The density, hardness, friction, and wear properties and acid corrosion rate of the coatings with different spraying distances were studied by X-ray diffraction, scanning electron microscopy, Rockwell hardness test, and friction and wear test. Research shows that the spraying distance has a significant effect on the density, hardness, porosity, friction, and wear properties and corrosion rate of the coating. When the spraying distance is 250 mm, the coating has the maximum density and hardness, the minimum porosity and corrosion rate, and the minimum friction coefficient and wear volume. Cu3.8ni and cr0.19fe0.7ni0.11 compounds in the coating have significant effects on the friction, wear, and hardness of the coating. The results show that too-high or too-low spraying distance will lead to pores and large particle agglomeration in the coating, which will affect the surface physical properties of the coating. Full article
(This article belongs to the Special Issue Advances in Processing, Simulation and Characterization of Alloys)
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14 pages, 7978 KiB  
Article
Upcycling Spent Selective-Catalytic-Reduction Catalyst to Produce Titanium Carbide Through Molten-Salt Electrolysis
by Weigang Cao, Qi Zhu, Long Zheng, Jiahao Jin, Xiangpeng Li and Yanan Xu
Crystals 2025, 15(2), 141; https://doi.org/10.3390/cryst15020141 - 28 Jan 2025
Viewed by 501
Abstract
The molten-salt electrolytic method was employed to recycle spent SCR catalyst to prepare TiC compound. A systematic investigation has been carried out through thermodynamic calculation and experimental analysis. The effects of graphite content, cell voltage, electrolyzing temperature, and electrolyzing time on electrolytic products [...] Read more.
The molten-salt electrolytic method was employed to recycle spent SCR catalyst to prepare TiC compound. A systematic investigation has been carried out through thermodynamic calculation and experimental analysis. The effects of graphite content, cell voltage, electrolyzing temperature, and electrolyzing time on electrolytic products were explored. The results show that a suitable amount of graphite content, high cell voltage, and a high electrolyzing temperature are beneficial to promote the formation of TiC compounds. It has also been found that the electroreduction of spent SCR catalyst/graphite can completely transform it into TiC compound in a relatively short time. The final electrolytic product is confirmed to be a solid solution of (Ti, W, Si, V)C. Meanwhile, the electrolytic process and reaction mechanism were investigated through the analysis of intermediates and the thermodynamic calculation. The electrolytic product has a potential application as reinforcement in metal matrix, which is a high additional-value utilization for spent SCR catalysts. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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18 pages, 1692 KiB  
Article
Complexes of Cd(II) with Nicotinamide, Nitrate, and Oxalate as Mixed Ligands: Synthesis, Characterization, and Biological Activity
by Laurențiu Pricop, Ioana Cristina Marinas, Anamaria Hanganu, Mihaela Ganciarov, Augustin M. Mădălan and Maria Olimpia Miclăuș
Crystals 2025, 15(2), 140; https://doi.org/10.3390/cryst15020140 - 27 Jan 2025
Viewed by 433
Abstract
Three complexes of Cd(II), [Cd(NA)2(NO3)2(H2O)2] (1), [Cd(NA)2(NO3)2(H2O)2]·2NA (2), and [Cd(ox)(NA)(H2O)]·H2O (3) (NA = nicotinamide, ox = oxalate) were synthesized [...] Read more.
Three complexes of Cd(II), [Cd(NA)2(NO3)2(H2O)2] (1), [Cd(NA)2(NO3)2(H2O)2]·2NA (2), and [Cd(ox)(NA)(H2O)]·H2O (3) (NA = nicotinamide, ox = oxalate) were synthesized and characterized. Complexes (1) and (2) are mononuclear, while complex (3) is a bidimensional polymeric coordination compound, with oxalate anions bridging metal ions in two different ways: µ2 bis-bidentate chelating manner and µ4 bis-bidentate bis-monodentate manner. The stereochemistry of Cd(II) in compounds (1) and (3) is a distorted pentagonal bipyramid, while in compound (2) it is a regular octahedron. Complexes (1) and (2) demonstrated significant activity against Enterococcus faecalis and Escherichia coli, showcasing their potential as effective antibacterial agents and inhibitors of microbial adhesion. The complexes were characterized by means of single-crystal X-ray diffraction, elemental analysis, FTIR (all complexes), 1H NMR, 13C NMR, fluorescence spectroscopy, and antimicrobial activity (complexes (1) and (2)). Full article
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53 pages, 13954 KiB  
Review
Progress in Icephobic Coatings for Wind Turbine Protection: Merging Chemical Innovation with Practical Implementation
by Ghazal Minoofar, Amirhossein Jalali Kandeloos, Mohammad Sadegh Koochaki and Gelareh Momen
Crystals 2025, 15(2), 139; https://doi.org/10.3390/cryst15020139 - 27 Jan 2025
Viewed by 1946
Abstract
Ice accumulation on wind turbine blades poses a significant challenge to turbine performance and safety, and these issues have led to extensive research on developing effective anti-icing methods. Polymer-based icephobic coatings have emerged as promising solutions, given their passive nature and low energy [...] Read more.
Ice accumulation on wind turbine blades poses a significant challenge to turbine performance and safety, and these issues have led to extensive research on developing effective anti-icing methods. Polymer-based icephobic coatings have emerged as promising solutions, given their passive nature and low energy requirements. However, developing effective icephobic coatings is a complex task. In addition to anti-icing properties, factors such as mechanical strength, durability, and resistance to UV, weathering, and rain erosion must be carefully considered to ensure these coatings withstand the harsh conditions faced by wind turbines. The main challenge in coating engineering is mastering the chemistry behind these coatings, as it determines their performance. This review provides a comprehensive analysis of the suitability of current icephobic coatings for wind turbine applications, emphasizing their alignment with present industrial standards and the underlying coating chemistry. Unlike previous works, which primarily focus on the mechanical aspects of icephobicity, this review highlights the critical yet underexplored role of chemical composition and explores recent advancements in polymer-based icephobic coatings. Additionally, earlier studies largely neglect the specific standards required for industrial applications on wind turbines. By demonstrating that no existing coating fully meets all necessary criteria, this work underscores both the urgency of developing icephobic coatings with improved durability and the pressing need to establish robust, application-specific standards for wind turbines. The review also combines insights from cutting-edge research on icephobic coatings that are coupled with active de-icing methods, known as the hybrid approach. By organizing and summarizing these innovations, the review aims to accelerate the development of reliable and efficient wind energy systems to pave the way for a cleaner and more sustainable future. Full article
(This article belongs to the Special Issue Celebrating the 10th Anniversary of International Crystallography)
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28 pages, 13067 KiB  
Review
Tamm Plasmons: Properties, Applications, and Tuning with Help of Liquid Crystals
by Victor Yu. Reshetnyak, Igor P. Pinkevych, Michael E. McConney, Timothy J. Bunning and Dean R. Evans
Crystals 2025, 15(2), 138; https://doi.org/10.3390/cryst15020138 - 27 Jan 2025
Viewed by 471
Abstract
This article provides a brief overview of the research on localized optical states called Tamm plasmons (TPs) and their potential applications, which have been extensively studied in recent decades. These states arise under the influence of incident light at the interface between a [...] Read more.
This article provides a brief overview of the research on localized optical states called Tamm plasmons (TPs) and their potential applications, which have been extensively studied in recent decades. These states arise under the influence of incident light at the interface between a metal film and a medium with the properties of a Bragg mirror, or between two media with the properties of a Bragg mirror. The localization of the states in the interfacial region is a consequence of the negative dielectric constant of the metal and the presence of a photonic band gap of the Bragg reflector. Optically, TPs appear as resonant reflection dips or peaks in the transmission and absorption spectra in the region corresponding to the photonic band gap. The relative simplicity of creating a Tamm structure and the significant sensitivity of TPs to its parameters make them attractive for applications. The formation of broadband and tunable TP modes in hybrid structures containing, in particular, rugate filters and porous distributed Bragg reflectors are considered. Considerable attention is paid to TP designs that include liquid crystals, which allow for the remote tuning of the TP spectrum without the mechanical restructuring of the system. The application of TPs in sensors, thermal emitters, absorbers, laser generation, and the experimental capabilities of TP-liquid crystal devices are also discussed. Full article
(This article belongs to the Special Issue Liquid Crystal Research and Novel Applications in the 21st Century)
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