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Crystals
Volume 16
Issue 1
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Crystals, Volume 16, Issue 1 (January 2026) – 78 articles

Cover Story (view full-size image): The polar oxide Lithium Niobate Tantalate represents a promising material platform for the next generation of highly integrated photonic and quantum optical multifunctional devices due to its pronounced tuning possibilities of the optical and/or electrical properties by composition. The luminescence of excitonic states with strong coupling to the lattice is one of the characteristic properties that, beyond its application potential, provides insights into the local structure of the solid solution. Using time-resolved spectroscopy, we find a non-exponential relaxation behaviour that can be attributed to a broad lifetime spectrum of self-trapped excitons and seems to indicate the presence of a pronounced structural disorder in comparison to the prominent edge compositions lithium niobate and lithium tantalate. View this paper
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18 pages, 9224 KB  
Article
Coupled Effects of Mg/Si Ratio and Recrystallization on Strength and Electrical Conductivity in Al-xMg-0.5Si Alloys
by Shanquan Deng, Xingsen Zhang, Junwei Zhu, Meihua Bian and Heng Chen
Crystals 2026, 16(1), 78; https://doi.org/10.3390/cryst16010078 - 22 Jan 2026
Viewed by 120
Abstract
The strategic balance between strength and electrical conductivity in Al-Mg-Si alloys is a critical challenge that must be overcome to enable their widespread adoption as viable alternatives to copper conductors in power transmission systems. To address this, the present study comprehensively investigates model [...] Read more.
The strategic balance between strength and electrical conductivity in Al-Mg-Si alloys is a critical challenge that must be overcome to enable their widespread adoption as viable alternatives to copper conductors in power transmission systems. To address this, the present study comprehensively investigates model alloys with Mg/Si ratios ranging from 1.0 to 2.0. A multi-faceted experimental approach was employed, combining tailored thermo-mechanical treatments (solution treatment, cold drawing, and isothermal annealing) with comprehensive microstructural characterization techniques, including electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM). The results elucidate a fundamental competitive mechanism governing property optimization: excess Mg atoms concurrently contribute to solid-solution strengthening via the formation of Cottrell atmospheres around dislocations, while simultaneously enhancing electron scattering, which is detrimental to conductivity. A critical synergy was identified at the Mg/Si ratio of 1.75, which promotes the dense precipitation of fine β″ phase while facilitating extensive recovery of high dislocation density. Furthermore, EBSD analysis confirmed the development of a microstructure comprising 74.1% high-angle grain boundaries alongside a low dislocation density (KAM ≤ 2°). This specific microstructural configuration effectively minimizes electron scattering while providing moderate grain boundary strengthening, thereby synergistically achieving an optimal balance between strength and electrical conductivity. Consequently, this work elucidates the key quantitative relationships and competitive mechanisms among composition (Mg/Si ratio), processing parameters, microstructure evolution, and final properties within the studied Al-xMg-0.5Si alloy system. These findings establish a clear design guideline and provide a fundamental understanding for developing high-performance aluminum-based conductor alloys with tailored Mg/Si ratios. Full article
(This article belongs to the Special Issue Microstructure, Properties and Characterization of Aluminum Alloys)
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17 pages, 2763 KB  
Article
Design and Characterization of Ceritinib Eutectic Solvent Systems for Pharmaceutical Formulation
by Iva Zokić, Dragana Pacina, Lara Krmelić, Valentina Erceg, Martina Miloloža Nikolić, Dajana Kučić Grgić and Jasna Prlić Kardum
Crystals 2026, 16(1), 77; https://doi.org/10.3390/cryst16010077 - 22 Jan 2026
Viewed by 141
Abstract
One of the main challenges facing the pharmaceutical industry today is the low solubility of active pharmaceutical ingredients (APIs), which leads to low bioavailability, reduced therapeutic efficacy, and the need for higher drug doses. Eutectic solvents (ES) offer a promising solution by effectively [...] Read more.
One of the main challenges facing the pharmaceutical industry today is the low solubility of active pharmaceutical ingredients (APIs), which leads to low bioavailability, reduced therapeutic efficacy, and the need for higher drug doses. Eutectic solvents (ES) offer a promising solution by effectively dissolving APIs, creating API-ES systems that can significantly improve drug solubility and delivery. In this study, three distinct ESs were prepared by combining various components, with their successful formation confirmed through Fourier Transform Infrared Spectroscopy. Key physicochemical properties, including the density, viscosity, and pH of the prepared solvents, were subsequently determined. Ceritinib (CRT), an API utilized in the treatment of non-small cell lung cancer, was then incorporated into the prepared ESs to yield the API-ES systems. A comparative analysis was conducted to assess the release profiles of pure CRT versus CRT within the API-ES systems. Furthermore, the permeability and diffusion coefficient of the drug within these systems were also determined. The results conclusively demonstrated that the formation of the API-ES system increased the solubility of CRT in water. This achievement represents a vital initial step toward optimizing the delivery of this drug and highlights the significant potential for developing a novel, improved pharmaceutical formulation. Full article
(This article belongs to the Section Biomolecular Crystals)
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10 pages, 2447 KB  
Article
A Fast-Response Vertical-Alignment In-Plane-Switching-Mode Liquid Crystal Display
by Feng Jiang, Jiangang Lu, Yi Li, Jing Wang, Kefeng Chen and Wei Li
Crystals 2026, 16(1), 76; https://doi.org/10.3390/cryst16010076 - 22 Jan 2026
Viewed by 276
Abstract
Fast-response liquid crystal (LC) displays have attracted attention for use as gaming displays with high frame rate and field-sequential displays. This work presents an LC display mode with vertical alignment and horizontal electric field driving, which achieves millisecond-scale response time. The proposed LC [...] Read more.
Fast-response liquid crystal (LC) displays have attracted attention for use as gaming displays with high frame rate and field-sequential displays. This work presents an LC display mode with vertical alignment and horizontal electric field driving, which achieves millisecond-scale response time. The proposed LC display mode may achieve an average grayscale-to-grayscale response time of 1.42 ms using low-rotational-viscosity LC material, optimized device architecture, and overdrive, offering a potential application for gaming displays and color-sequential displays. Full article
(This article belongs to the Collection Liquid Crystals and Their Applications)
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16 pages, 3133 KB  
Article
Spatially Selective Boundary Oscillation for Defect Structures Control in Two-Dimensional Liquid Crystal Confinement
by Ruifen Zhang, Shilong Xin and Xin Wen
Crystals 2026, 16(1), 75; https://doi.org/10.3390/cryst16010075 - 22 Jan 2026
Viewed by 225
Abstract
Modulating boundary conditions offers a powerful approach to generate and control topological defects, which govern the structure and dynamics of liquid crystals. Here, we employ Langevin dynamics simulations to study defect structure formation in two-dimensional colloidal liquid crystals confined within a square cavity [...] Read more.
Modulating boundary conditions offers a powerful approach to generate and control topological defects, which govern the structure and dynamics of liquid crystals. Here, we employ Langevin dynamics simulations to study defect structure formation in two-dimensional colloidal liquid crystals confined within a square cavity whose walls undergo periodic oscillation. The spatial topology of the driving boundary from single-side to global four-wall actuation directly sets the symmetry of energy input, which in turn determines its spatial gradient and distribution. By controlling boundary vibrations through amplitude and frequency, we demonstrate the emergence of novel steady-state patterns and transformations between distinct defect structures, identified via the local order parameter. Four-wall oscillation generates richer structural diversity due to its higher spatial symmetry. Structural transitions are quantified by tracking a global director angle under two driving regimes: varying amplitude at fixed frequency (f = 2.0), and varying frequency at fixed amplitude (A = 1.0). Our results establish that the manner of energy injection determined by the choice of boundary motion mode governs the emergent defect architectures, providing a general route to engineer non-equilibrium phases under confinement. Full article
(This article belongs to the Section Liquid Crystals)
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16 pages, 12349 KB  
Article
Pb-Apatite Framework as a Generator of Novel Flat-Band CuO-Based Physics
by Rafał Kurleto, Stephan Lany, Dimitar Pashov, Swagata Acharya, Mark van Schilfgaarde and Daniel S. Dessau
Crystals 2026, 16(1), 74; https://doi.org/10.3390/cryst16010074 - 22 Jan 2026
Viewed by 210
Abstract
Based upon density functional theory (DFT) calculations, we present the basic electronic structure of CuPb9(PO4)6O (Cu-doped lead apatite, aka LK-99), in two scenarios: (1) where the structure is constrained to the P3 symmetry and (2) where no [...] Read more.
Based upon density functional theory (DFT) calculations, we present the basic electronic structure of CuPb9(PO4)6O (Cu-doped lead apatite, aka LK-99), in two scenarios: (1) where the structure is constrained to the P3 symmetry and (2) where no symmetry is imposed. At the DFT level, the former is predicted to be metallic while the latter is found to be a charge-transfer insulator. In both cases the filling of these states is nominally d9, consistent with the standard Cu2+ valence state, and Cu with a local magnetic moment of order 0.7 μB. In the metallic case we find these states to be unusually flat (∼0.2 eV dispersion), giving a very high density of electronic states (DOS) at the Fermi level that we argue can be a host for novel electronic physics. The flatness of the bands is the likely origin of symmetry-lowering gapping possibilities that would remove the spectral weight from EF. Motivated by some initial experimental observations of metallic or semiconducting behavior, we propose that disorder (likely structural) is responsible for closing the gap. Here, we consider a variety of possibilities that could possibly close the charge-transfer gap but limit consideration to kinds of disorder that preserve electron count. Of the possible kinds we considered (spin disorder, O populating vacancy sites, and Cu on less energetically favorable Pb sites), the local Cu moment, and consequently the charge-transfer gap, remains robust. We conclude that disorder responsible for metallic behavior entails some kind of doping where the electron count changes. Further, we claim that the emergence of the flat bands should be due to weak wave function overlap between the orbitals on Cu and O sites, owing to the directional character of the constituent orbitals. Therefore, finding an appropriate host structure for minimizing hybridization between Cu and O while allowing them to still weakly interact should be a promising route for generating flat bands at EF which can lead to interesting electronic phenomena, regardless of whether LK-99 is a superconductor. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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9 pages, 1688 KB  
Article
Morphological Evolution of Nickel–Fullerene Thin Film Mixtures
by Giovanni Ceccio, Kazumasa Takahashi, Romana Mikšová, Yuto Kondo, Eva Štěpanovská, Josef Novák, Sebastiano Vasi and Jiří Vacik
Crystals 2026, 16(1), 73; https://doi.org/10.3390/cryst16010073 - 22 Jan 2026
Viewed by 130
Abstract
Hybrid systems consisting of metal–fullerene composites exhibit intriguing properties but often suffer from thermal instability. With proper control, such instability can be harnessed to enable the formation of sophisticated nanostructures with nanometric precision. These self-organization phenomena are not limited to thermal stimulation alone [...] Read more.
Hybrid systems consisting of metal–fullerene composites exhibit intriguing properties but often suffer from thermal instability. With proper control, such instability can be harnessed to enable the formation of sophisticated nanostructures with nanometric precision. These self-organization phenomena are not limited to thermal stimulation alone but can also be triggered by other external stimuli. In this work, we investigate the morphological evolution of thin films composed of evaporated C60 and sputtered nickel mixtures, focusing on how external stimuli influence both their structural and electrical properties. Thin films were prepared under controlled deposition conditions, and their surface morphology was analyzed using advanced characterization techniques. Progressive changes in film morphology were observed as a function of composition and external treatment, highlighting the interplay between metallic and molecular components. In particular, it was observed that, due to the annealing treatment, the sample undergoes strong phase separation, with the formation of structures tens of microns in diameter and an increase in electrical resistance, exhibiting insulating behavior. These findings provide insights into the mechanisms governing hybrid thin film formation and suggest potential applications in electronic, optoelectronic, and energy-related devices. Full article
(This article belongs to the Special Issue Metal Coordination Complexes for Optical and Chiro-Optical Applications)
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19 pages, 6327 KB  
Article
Tailoring the Microstructure and Mechanical Properties of Laser Directed Energy–Deposited Inconel 718 Alloys via Ultrasonic Frequency Modulation
by Bo Peng, Mengmeng Zhang, Xiaoqiang Zhang, Ze Chai, Fahai Ba and Xiaoqi Chen
Crystals 2026, 16(1), 72; https://doi.org/10.3390/cryst16010072 - 21 Jan 2026
Viewed by 275
Abstract
Ultrasonic-assisted laser-directed energy deposition (UA-DED) is a promising combined technology for manufacturing high-value thin-walled Inconel 718 components in aerospace. Nevertheless, the optimal ultrasonic frequency—a key parameter for achieving desirable performance in thin-walled Inconel 718 alloys—remains to be determined. In this study, we systematically [...] Read more.
Ultrasonic-assisted laser-directed energy deposition (UA-DED) is a promising combined technology for manufacturing high-value thin-walled Inconel 718 components in aerospace. Nevertheless, the optimal ultrasonic frequency—a key parameter for achieving desirable performance in thin-walled Inconel 718 alloys—remains to be determined. In this study, we systematically investigated the influence of ultrasonic frequency (12–20 kHz) on the microstructure and mechanical properties of thin-walled Inconel 718 fabricated by UA-DED. The results revealed that an ultrasonic frequency of 20 kHz was optimal and can yield significant improvements in the microstructures of the as-deposited sample coordinate planes, manifested by the complete suppression of large pores, three-dimensional refinement of the γ matrix grains, alleviation of Nb and Mo segregation, the reduction of fragmented Laves particles, a decrease in residual macroscopic stresses, and homogeneous distributions of γ′/γ″ phases and γ-grain orientation. Meanwhile, the application of a 20 kHz ultrasonic frequency endows the manufactured thin-walled 718 parts with superior mechanical properties, including a tensile strength of 899 MPa in the laser scanning direction and 877 MPa in the build direction, along with the corresponding elongations of 34.8% and 38.9%. This work demonstrates the potential of modulating ultrasonic frequency to tailor microstructures and produce high-performance thin-walled Inconel 718 aerospace components. Full article
(This article belongs to the Special Issue Microstructure and Properties of Metals and Alloys)
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15 pages, 7578 KB  
Article
Effect of Titanium Content and Mechanical Alloying Time on the Formation of Nanocrystalline Solid Solutions in the Ni–Al–Ti System
by Yerkezhan Tabiyeva, Dias Yerbolat, Sayat Zakerov, Yerkhat Dauletkhanov, Azamat Urkunbay, Elfira Sagymbekova and Nurgamit Kantay
Crystals 2026, 16(1), 71; https://doi.org/10.3390/cryst16010071 - 21 Jan 2026
Viewed by 221
Abstract
This work investigates the effect of titanium content and the duration of mechanical alloying on the structural and phase state of powder mixtures in the Ni–Al–Ti system. The initial mixtures of Ni68Al25Ti7, Ni72Al22Ti [...] Read more.
This work investigates the effect of titanium content and the duration of mechanical alloying on the structural and phase state of powder mixtures in the Ni–Al–Ti system. The initial mixtures of Ni68Al25Ti7, Ni72Al22Ti6, Ni70Al21Ti9, and Ni75Al25 were subjected to high-energy milling in a planetary ball mill for 1–6 h. It was found that the addition of titanium accelerates the dissolution of components and promotes the formation of a supersaturated fcc Ni(Al,Ti) solid solution. The most pronounced effects were observed for the Ni70Al21Ti9 composition, where after 6 h of alloying, the minimum crystallite size (11.3 nm) and maximum lattice strain (1.52%) were achieved. It is shown that titanium reduces the tendency for cold welding and promotes more uniform particle refinement. The optimal conditions for synthesizing a nanocrystalline solid solution with a homogeneous structure are a titanium content of 9 at.% and a mechanical alloying duration of 6 h. The resulting powders are promising for subsequent sintering and application in structural and heat-resistant intermetallic alloys and coatings. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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17 pages, 2161 KB  
Article
Structure-Related Properties in AlP Nanoparticles Across One- and Two-Dimensional Architectures
by Fotios I. Michos, Christina Papaspiropoulou, Nikos Aravantinos-Zafiris and Michail M. Sigalas
Crystals 2026, 16(1), 70; https://doi.org/10.3390/cryst16010070 - 21 Jan 2026
Viewed by 186
Abstract
A systematic density functional theory (DFT) and time-dependent DFT (TD-DFT) investigation of aluminum phosphide (AlxPx) nanoparticles with diverse dimensionalities and geometries is presented. Starting from a cubic-like Al4P4 building block, a series of one-dimensional (1D) elongated, [...] Read more.
A systematic density functional theory (DFT) and time-dependent DFT (TD-DFT) investigation of aluminum phosphide (AlxPx) nanoparticles with diverse dimensionalities and geometries is presented. Starting from a cubic-like Al4P4 building block, a series of one-dimensional (1D) elongated, two-dimensional (2D) exotic, and extended sheet-like nanostructures was constructed, enabling a unified structure–property analysis across size and topology. Optical absorption and infrared (IR) vibrational spectra were computed and correlated with geometric motifs, revealing pronounced shape-dependent tunability. Compact and highly interconnected 2D architectures exhibit red-shifted absorption and enhanced vibrational polarizability, whereas elongated or low-connectivity motifs lead to blue-shifted optical responses and stiffer vibrational frameworks. Benchmark comparisons indicate that CAM-B3LYP excitation energies closely reproduce reference EOM-CCSD trends for the lowest singlet states. Binding energy and HOMO-UMO gap analyses confirm increasing thermodynamic stability with size and dimensionality, alongside topology-driven electronic modulation. These findings establish AlP nanostructures as highly tunable platforms for optoelectronic and vibrationally active applications. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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13 pages, 4030 KB  
Article
Selenoether-Linked Liquid Crystal Trimers and the Twist-Bend Nematic Phase
by Yuki Arakawa and Takuma Shiba
Crystals 2026, 16(1), 69; https://doi.org/10.3390/cryst16010069 - 21 Jan 2026
Viewed by 223
Abstract
Bent-shaped liquid crystal (LC) dimers, trimers, and oligomers are intriguing because of their unique liquid crystallinities, which have gained further impetus after the identification of the twist-bend nematic (NTB) phase in these molecules. LC trimers exhibiting the NTB phase still [...] Read more.
Bent-shaped liquid crystal (LC) dimers, trimers, and oligomers are intriguing because of their unique liquid crystallinities, which have gained further impetus after the identification of the twist-bend nematic (NTB) phase in these molecules. LC trimers exhibiting the NTB phase still remain relatively rare compared to the predominant LC dimers. We report the first homologs of selenium-linked LC trimers, 4,4′-bis[ω-(4-cyanobiphenyl-4′-ylseleno)alkoxy]biphenyls (CBSenOBOnSeCB) with carbon numbers in the alkyl-chain spacers, n = 7 or 9). Polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction (XRD) measurements were performed to investigate the phase transition behavior and mesophase structures of the trimers. Both CBSenOBOnSeCB trimers exhibited nematic (N) and NTB phases. The XRD measurements revealed the presence of smectic A-like cybotactic clusters with a triply intercalated structure in the N and NTB phases. The LC phase transition temperatures of CBSenOBOnSeCB were lower than those of the already-known ether-linked CBOnOBOnOCB and thioether-linked CBSnOBOnSCB counterparts. This trend is ascribed to the enhanced molecular bending and molecular flexibility of CBSenOBOnSeCB, which are caused by the smaller bond angle and greater bond flexibility of C–Se–C compared to C–O–C and C–S–C. This study offers a new molecular design for multiply linked LC oligomers with heavier chalcogen atoms. Full article
(This article belongs to the Special Issue State-of-the-Art Liquid Crystals Research in Japan (2nd Edition))
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14 pages, 1777 KB  
Article
Machine-Learning-Based Screening of Perovskite Cathodes for Low-Temperature Solid Oxide Fuel Cell Operation
by Mingxuan Deng, Yang Yu, Yunhao Wang, Zhuangzhuang Ma, Linyuan Lu, Tianhao Rui, Yulin Lan, Jiajun Linghu, Nannan Han, Yiyan Li, Zhipeng Li and Haibin Zhang
Crystals 2026, 16(1), 68; https://doi.org/10.3390/cryst16010068 - 20 Jan 2026
Viewed by 293
Abstract
The discovery of cathode materials that simultaneously exhibit high oxygen-reduction activity, robust stability, and low cost is pivotal to moving solid oxide fuel cells (SOFCs) from the laboratory into commercial deployment. To address this challenge, we compile the largest perovskite dataset to date [...] Read more.
The discovery of cathode materials that simultaneously exhibit high oxygen-reduction activity, robust stability, and low cost is pivotal to moving solid oxide fuel cells (SOFCs) from the laboratory into commercial deployment. To address this challenge, we compile the largest perovskite dataset to date parameterized by the oxygen tracer surface exchange coefficient (k*). Using only readily obtainable elemental and structural descriptors, we develop machine-learning models that surpass existing approaches in both accuracy and computational efficiency. Specifically, by integrating Mahalanobis-distance-based applicability-domain analysis with random forest-enhanced property descriptors and support vector regression, we high-throughput-screen 1.3 million ABO3 compositions and curate a candidate list that balances thermodynamic stability, cost, and oxygen-reduction activity. Beyond prediction accuracy, SHAP interpretation reveals strong physical correlations between the enhanced descriptors and k*, highlighting the coefficient of thermal expansion, O p-band center, and A-site ionic radius as the dominant factors governing oxygen exchange kinetics. Finally, we identify 209 promising perovskite cathodes predicted to outperform LSC in the low-temperature regime, offering promising directions for experimental realization of practical low-temperature SOFCs. Full article
(This article belongs to the Section Materials for Energy Applications)
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26 pages, 550 KB  
Review
Recovery of Critical Metals from Waste-Printed Circuit Boards for Sustainable Energy Transition
by Lucian-Cristian Pop, Szabolcs Szima and Szabolcs Fogarasi
Crystals 2026, 16(1), 67; https://doi.org/10.3390/cryst16010067 - 20 Jan 2026
Viewed by 468
Abstract
It is undeniable that rapid population increase coupled with growing resource constraints are making the demand for smart and sustainable solutions more urgent than ever to secure future resources for the transition to sustainable energy production. To address these issues, it is necessary [...] Read more.
It is undeniable that rapid population increase coupled with growing resource constraints are making the demand for smart and sustainable solutions more urgent than ever to secure future resources for the transition to sustainable energy production. To address these issues, it is necessary to define innovative approaches that can exploit more efficiently and extensively the resources we have at our disposal. Consequently, this paper provides an overview of the potential benefits of processing waste-printed circuit boards (WPCBs) that are generated in large quantities and, due to their high metal content, can emerge as an adequate and profitable supply of critical metals, such as copper, aluminum, and nickel, which are essential for green energy transition. The review promotes the idea of industrial symbiosis as a concept that goes beyond circular economy and can integrate WPCB treatment and manufacturing processes related to sustainable energy transition, although they are different industrial sectors that can be even regionally separated. Major metal recovery processes from WPCBs are examined and discussed, with the primary focus on the performances of copper, aluminum, and nickel production, while additional metals relevant to the energy transition are also highlighted. Finally, the review paper argues and exemplifies that the recovered metals from WPCBs have the required properties to be supplied into the manufacturing processes of wind turbines, solar panels, and lithium-ion batteries. Full article
(This article belongs to the Special Issue Exploring New Materials for the Transition to Sustainable Energy)
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14 pages, 3220 KB  
Article
Effect of Stone Powder Content on the Properties and Microstructure of Nuclear Power-Manufactured Sand Concrete
by Xiangqin Du, Zhilong Liu, Rongfei Chen, Zhenhua Zhao, Xiaobo Hao, Xiaofan Peng and Hongmei Wu
Crystals 2026, 16(1), 66; https://doi.org/10.3390/cryst16010066 - 19 Jan 2026
Viewed by 241
Abstract
Stone powder is an inevitable by-product generated during the processing of manufactured sand and gravel. Waste stone powder has been proven to affect concrete properties and has been applied in the transportation and hydropower fields. This study aims to convert waste granite stone [...] Read more.
Stone powder is an inevitable by-product generated during the processing of manufactured sand and gravel. Waste stone powder has been proven to affect concrete properties and has been applied in the transportation and hydropower fields. This study aims to convert waste granite stone powder (GP) to nuclear power concrete by replacing manufactured sand, investigating its effect on the workability, compressive strength, splitting tensile strength, impermeability, and freezing resistance of nuclear power concrete. The mechanism was further elucidated through thermogravimetric (TG), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) techniques. The results show that with the increase in GP content, the slump, compressive strength, and splitting tensile strength of concrete increase first and then decrease, and the seepage height under pressure water decreases first and then increases. The workability, strength, and impermeability of concrete are optimal when GP content is 11.0%. Reasonable GP content improves the compactness of concrete by filling pores and optimizing aggregate gradation, resulting in decreases in porosity, with the size being the most probable and average pore size. Full article
(This article belongs to the Special Issue Synergizing Crystallography, Mineral Materials Science and Solid Waste Upcycling for Sustainable Materials Innovation)
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11 pages, 1117 KB  
Article
Process Optimization and Performance Study of ZnO Nanowires Grown by the VLS Method
by Zhi-Yue Li, Hai-Xiao Luo and Ting-Yong Chen
Crystals 2026, 16(1), 65; https://doi.org/10.3390/cryst16010065 - 18 Jan 2026
Cited by 1 | Viewed by 224
Abstract
One-dimensional ZnO nanowires offer significant potential for optoelectronic applications, though their controlled synthesis remains challenging. This study optimized ZnO nanowire growth via carbothermal reduction vapor transport based on the vapor–liquid–solid mechanism. Key parameters investigated were gold catalyst thickness and annealing, source temperature, system [...] Read more.
One-dimensional ZnO nanowires offer significant potential for optoelectronic applications, though their controlled synthesis remains challenging. This study optimized ZnO nanowire growth via carbothermal reduction vapor transport based on the vapor–liquid–solid mechanism. Key parameters investigated were gold catalyst thickness and annealing, source temperature, system pressure, and oxygen concentration. Results show that thinner Au films promote high-density, small-diameter nanowires. An optimal source temperature window (950–1000 °C) was identified, while pressure and oxygen content critically influenced growth mode by modulating vapor supersaturation. Under optimized conditions, aligned single-crystalline ZnO nanowires with hexagonal wurtzite structure were achieved. Structural and optical characterization confirmed high crystallinity and strong near-band-edge emission, demonstrating the efficacy of the developed approach for tailored nanowire synthesis. Full article
(This article belongs to the Special Issue Research and Applications of ZnO Thin Films)
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19 pages, 3518 KB  
Article
Al/Graphene Co-Doped ZnO Electrodes: Impact on CTS Thin-Film Solar Cell Efficiency
by Done Ozbek, Meryem Cam, Guldone Toplu, Sevde Erkan, Serkan Erkan, Ali Altuntepe, Kasim Ocakoglu, Sakir Aydogan, Yavuz Atasoy, Mehmet Ali Olgar and Recep Zan
Crystals 2026, 16(1), 64; https://doi.org/10.3390/cryst16010064 - 17 Jan 2026
Viewed by 246
Abstract
This study investigates pristine and doped ZnO thin films fabricated via the sol-gel technique, aiming to address efficiency challenges when used as transparent conductive oxide (TCO) layers in thin-film solar cells. ZnO was first doped with aluminum (Al), and subsequently with both Al [...] Read more.
This study investigates pristine and doped ZnO thin films fabricated via the sol-gel technique, aiming to address efficiency challenges when used as transparent conductive oxide (TCO) layers in thin-film solar cells. ZnO was first doped with aluminum (Al), and subsequently with both Al and reduced graphene oxide (rGO), to evaluate the individual and combined effects of these dopants. The optimal pH value for the ZnO structure was initially determined, with the film produced at pH 9 exhibiting the most favorable characteristics. Al doping was then optimized at a ratio of Al/(Al + Zn) = 0.2, followed by optimization of the graphene content at 1.5 wt%. In this context, the structural, optical, and electrical properties of pristine ZnO, Al-doped ZnO (AZO), and Al and graphene co-doped ZnO (Gr:AZO) thin films were systematically investigated. These films were integrated as TCO layers into Cu2SnS3 (CTS)-based thin-film solar cells fabricated via physical vapor deposition (PVD). The cell architecture employed an 80 nm pristine ZnO window layer, while the doped ZnO films (300 nm) served as TCO layers. To assess the influence of the chemically deposited top layers, device performance was compared against a reference cell in which all layers were fabricated entirely using PVD. As expected, the reference cell exhibited superior performance compared to the cell whose AZO layer deposited chemically; however, the incorporation of both Al and graphene significantly enhanced the efficiency of the chemically modified cell, outperforming devices using only pristine or singly doped ZnO films. These results demonstrate the promising potential of co-doped solution-processed ZnO films as an alternative TCO layer in improving the performance of thin-film solar cell technologies. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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16 pages, 2724 KB  
Article
Sustainable Routes to a Soluble Anthelmintic Thiabendazole Organic Salt
by Ilenia D’Abbrunzo, Elisa Zampieri, Maja Bjelošević Žiberna, Serena Bertoni, Cécile Häberli, Jennifer Keiser and Beatrice Perissutti
Crystals 2026, 16(1), 63; https://doi.org/10.3390/cryst16010063 - 16 Jan 2026
Viewed by 245
Abstract
A new organic salt of thiabendazole with p-toluenesulfonic acid was successfully synthesized by mechanochemistry. Notably, the same crystalline form and morphology were obtained both through neat grinding and liquid-assisted grinding using 4-methyltetrahydropyran, a sustainable solvent not yet commonly employed in mechanochemical processes. The [...] Read more.
A new organic salt of thiabendazole with p-toluenesulfonic acid was successfully synthesized by mechanochemistry. Notably, the same crystalline form and morphology were obtained both through neat grinding and liquid-assisted grinding using 4-methyltetrahydropyran, a sustainable solvent not yet commonly employed in mechanochemical processes. The resulting salt crystallizes as a hydrate with impressive physical stability for up to 18 months under four storage conditions, including 40 °C. Comprehensive solid-state characterization (PXRD, DSC, TGA, HSM, SEM) confirmed the phase identity, purity, and thermal behavior of the material, while FTIR spectroscopy provided insight into the intermolecular interactions driving salt formation and stabilizing the crystalline water. In comparison to pure thiabendazole, the hydrate salt exhibited a remarkable ~70-fold increase in solubility and significantly improved intrinsic dissolution rate over the entire study period. Importantly, the in vivo evaluation in the Heligmosomoides polygyrus mouse model of the salt and the pure drug revealed similar moderate reductions in worm burden, indicating that salt formation does not compromise anthelmintic efficacy. Full article
(This article belongs to the Section Crystal Engineering)
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14 pages, 5048 KB  
Article
Transmissive Multilayer Geometric Phase Gratings Using Water-Soluble Alignment Material
by Fatemeh Abbasi, Kristiaan Neyts, Inge Nys and Jeroen Beeckman
Crystals 2026, 16(1), 62; https://doi.org/10.3390/cryst16010062 - 15 Jan 2026
Viewed by 285
Abstract
Multilayer liquid crystal devices can offer enhanced optical functionalities for augmented reality and photonic applications, but fabrication remains severely limited by solvent incompatibility between photoalignment materials and underlying polymerized layers. Conventional photoalignment agents use aggressive solvents like N,N-dimethylformamide that damage polymerized substrates, necessitating [...] Read more.
Multilayer liquid crystal devices can offer enhanced optical functionalities for augmented reality and photonic applications, but fabrication remains severely limited by solvent incompatibility between photoalignment materials and underlying polymerized layers. Conventional photoalignment agents use aggressive solvents like N,N-dimethylformamide that damage polymerized substrates, necessitating protective interlayers. This study demonstrates a water-soluble photoalignment approach using AbA-2522 that eliminates these fabrication barriers. The water-soluble alignment material enables direct multilayer processing without layer damage while maintaining alignment quality equivalent to conventional materials. We successfully fabricate compact transmissive devices integrating liquid crystal polarization gratings with quarter-wave plates, achieving a first-order diffraction efficiency of 65.4% for 9 μm period gratings for linearly polarized incident light (λ = 457 nm). The multilayer structure exhibits highly selective polarization-dependent diffraction with efficiency ratios exceeding 10:1 between preferred and suppressed orders, eliminating external polarization control elements. Polarized optical microscopy confirms excellent alignment uniformity, while the fabrication process offers environmental benefits and reduced complexity. This approach establishes a practical pathway for advanced multilayer photonic devices critical for next-generation augmented reality systems and photonic integration, addressing fundamental challenges that have limited multilayer liquid crystal device development. Full article
(This article belongs to the Collection Liquid Crystals and Their Applications)
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29 pages, 4522 KB  
Article
Machine Learning-Driven Prediction of Microstructural Evolution and Mechanical Properties in Heat-Treated Steels Using Gradient Boosting
by Saurabh Tiwari, Khushbu Dash, Seongjun Heo, Nokeun Park and Nagireddy Gari Subba Reddy
Crystals 2026, 16(1), 61; https://doi.org/10.3390/cryst16010061 - 15 Jan 2026
Viewed by 350
Abstract
Optimizing heat treatment processes requires an understanding of the complex relationships between compositions, processing parameters, microstructures, and properties. Traditional experimental approaches are costly and time-consuming, whereas machine learning methods suffer from critical data scarcity. In this study, gradient boosting models were developed to [...] Read more.
Optimizing heat treatment processes requires an understanding of the complex relationships between compositions, processing parameters, microstructures, and properties. Traditional experimental approaches are costly and time-consuming, whereas machine learning methods suffer from critical data scarcity. In this study, gradient boosting models were developed to predict microstructural phase fractions and mechanical properties using synthetic training data generated from an established metallurgical theory. A 400-sample dataset spanning eight AISI steel grades was created based on Koistinen–Marburger martensite kinetics, the Grossmann hardenability theory, and empirical property correlations from ASM handbooks. Following systematic hyperparameter optimization via 5-fold cross-validation, gradient boosting achieved R2 = 0.955 for hardness (RMSE = 2.38 HRC), R2 = 0.949 for tensile strength (RMSE = 87.6 MPa), and R2 = 0.936 for yield strength, outperforming the Random Forest, Support Vector Regression, and Neural Networks by 7–13%. Feature importance analysis identified the tempering temperature (38.4%), carbon equivalent (15.4%), and carbon content (13.0%) as the dominant factors. Model predictions demonstrated physical consistency with the literature data (mean error of 1.8%) and satisfied the fundamental metallurgical relationships. This methodology provides a scalable and cost-effective approach for heat treatment optimization by reducing experimental requirements based on learning curve analysis while maintaining prediction accuracy within the measurement uncertainty. Full article
(This article belongs to the Special Issue Investigation of Microstructural and Properties of Steels and Alloys)
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16 pages, 36371 KB  
Article
Synergistic Integration of Drop-Casting with Sonication and Thermal Treatment for Fabrication of MWCNT-Coated Conductive Cotton Fabrics
by Muhammad Shahbaz and Hiroshi Furuta
Crystals 2026, 16(1), 60; https://doi.org/10.3390/cryst16010060 - 14 Jan 2026
Viewed by 507
Abstract
This study introduces a synergistic drop-casting, sonication, and thermal treatment (DSTT) method for fabricating multi-walled carbon nanotube (MWCNT)-coated conductive cotton fabrics. The process produced uniform MWCNT networks with a minimum sheet resistance of 0.072 ± 0.004 kΩ/sq. at ~30 wt.% loading. Scanning electron [...] Read more.
This study introduces a synergistic drop-casting, sonication, and thermal treatment (DSTT) method for fabricating multi-walled carbon nanotube (MWCNT)-coated conductive cotton fabrics. The process produced uniform MWCNT networks with a minimum sheet resistance of 0.072 ± 0.004 kΩ/sq. at ~30 wt.% loading. Scanning electron microscopy confirmed an improved MWCNT network. Reproducibility was demonstrated for different fabric sizes, with resistance values remaining consistent within experimental errors. Stability tests showed only minor changes in sheet resistance after 16 weeks of ambient storage and periodic manual bending. Compared to conventional methods such as room-temperature drying, vacuum drying, and sonication alone, DSTT consistently performed better, yielding fabrics with lower resistance and more reliable conductivity. These results highlight DSTT as a reproducible and scalable method for producing conductive cotton fabrics suitable for smart textiles and wearable electronics. Full article
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17 pages, 2160 KB  
Article
Effect of Sandblasting, Tribochemical Silica Coating, CO2 Laser, and Plasma-Enhanced Chemical Vapor Deposition on Surface Characteristics and Shear Bond Strength of 3Y-TZP Zirconia
by Mohammed A. Alrabiah and Fahad Alkhudhairy
Crystals 2026, 16(1), 59; https://doi.org/10.3390/cryst16010059 - 14 Jan 2026
Viewed by 248
Abstract
To evaluate the influence of different surface conditioning protocols—sandblasting (SB), tribochemical silica coating (TBC), CO2 laser irradiation, and plasma-enhanced chemical vapor deposition (PECVD-Si coating for 49 min) on surface roughness (Ra), surface morphology, and composite-to-zirconia shear bond strength (SBS). Eighty 3Y-TZP plates [...] Read more.
To evaluate the influence of different surface conditioning protocols—sandblasting (SB), tribochemical silica coating (TBC), CO2 laser irradiation, and plasma-enhanced chemical vapor deposition (PECVD-Si coating for 49 min) on surface roughness (Ra), surface morphology, and composite-to-zirconia shear bond strength (SBS). Eighty 3Y-TZP plates were randomly allocated into four groups (n = 20) based on surface conditioning protocol: Group 1 (SB), Group 2 (CO2 laser), Group 3 (TBC), and Group 4 (PECVD-Si coating for 49 min). From each group, five specimens underwent Ra assessment using a contact profilometer, and five specimens were examined for surface morphology via scanning electron microscopy (SEM). The remaining ten specimens received resin composite buildup, followed by artificial aging. Subsequently, SBS testing was performed using a universal testing machine, and failure modes were evaluated under a stereomicroscope. Statistical analysis was conducted using one-way ANOVA with post hoc Tukey test and chi-square for fracture assessment(α = 0.05). Group 1 (SB) demonstrated the lowest Ra (0.844 ± 0.063 µm) and SBS (12.21 ± 4.6 MPa), whereas Group 4 (PECVD-Si coating for 49 min) exhibited the highest Ra (1.388 ± 0.098 µm) and SBS (30.48 ± 2.5 MPa). Intergroup comparison revealed no statistically significant differences between Groups 2 and 3 for both Ra and SBS values (p > 0.05). However, Groups 1 and 4 differed significantly in both parameters (p < 0.05). PECVD-based silica coating for 49 min demonstrated superior surface conditioning efficacy for 3Y-TZP, yielding significantly higher Ra and SBS values compared to sandblasting, tribochemical silica coating, and CO2 laser irradiation. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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13 pages, 3254 KB  
Article
Thermal Expansion, Microstructure and Mechanical Properties of Rapid Microwave Sintering Mn3Cu0.5Ge0.5N0.9C0.1 in Nitrogen Atmosphere
by Hao Zhang, Yongjuan Dai, Zhishan Hu, Cuihong Han, Bo Li, Dong Guo and Zhonghua Sun
Crystals 2026, 16(1), 58; https://doi.org/10.3390/cryst16010058 - 14 Jan 2026
Viewed by 191
Abstract
Microwave sintering enabled the efficient fabrication of bulk Mn3Cu0.5Ge0.5N0.9C0.1 NTE materials in 3–5 h, versus 2 to 8 days for conventional methods. The microwave approach demonstrated high efficiency and energy savings. By adjusting temperature [...] Read more.
Microwave sintering enabled the efficient fabrication of bulk Mn3Cu0.5Ge0.5N0.9C0.1 NTE materials in 3–5 h, versus 2 to 8 days for conventional methods. The microwave approach demonstrated high efficiency and energy savings. By adjusting temperature and dwell time, the NTE operating range can be shifted to lower temperatures. Under the optimized condition of 800 °C for 4 h, the resulting bulk material achieved an NTE coefficient of −20.56 × 10−6 K−1 over a temperature interval ΔT of 88 K (from 159 K to 247 K), along with favorable densification and high hardness. The demonstrated processing efficiency, microstructural control, and tunable NTE properties establish a solid foundation for potential industrial scale-up. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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23 pages, 1151 KB  
Article
CNN–BiLSTM–Attention-Based Hybrid-Driven Modeling for Diameter Prediction of Czochralski Silicon Single Crystals
by Pengju Zhang, Hao Pan, Chen Chen, Yiming Jing and Ding Liu
Crystals 2026, 16(1), 57; https://doi.org/10.3390/cryst16010057 - 13 Jan 2026
Viewed by 254
Abstract
High-precision prediction of the crystal diameter during the growth of electronic-grade silicon single crystals is a critical step for the fabrication of high-quality single crystals. However, the process features high-temperature operation, strong nonlinearities, significant time-delay dynamics, and external disturbances, which limit the accuracy [...] Read more.
High-precision prediction of the crystal diameter during the growth of electronic-grade silicon single crystals is a critical step for the fabrication of high-quality single crystals. However, the process features high-temperature operation, strong nonlinearities, significant time-delay dynamics, and external disturbances, which limit the accuracy of conventional mechanism-based models. In this study, mechanism-based models denote physics-informed heat-transfer and geometric models that relate heater power and pulling rate to diameter evolution. To address this challenge, this paper proposes a hybrid deep learning model combining a convolutional neural network (CNN), a bidirectional long short-term memory network (BiLSTM), and self-attention to improve diameter prediction during the shoulder-formation and constant-diameter stages. The proposed model leverages the CNN to extract localized spatial features from multi-source sensor data, employs the BiLSTM to capture temporal dependencies inherent to the crystal growth process, and utilizes the self-attention mechanism to dynamically highlight critical feature information, thereby substantially enhancing the model’s capacity to represent complex industrial operating conditions. Experiments on operational production data collected from an industrial Czochralski (Cz) furnace, model TDR-180, demonstrate improved prediction accuracy and robustness over mechanism-based and single data-driven baselines, supporting practical process control and production optimization. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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12 pages, 2079 KB  
Communication
Synthesis, Structure, and Physical Properties of RbCr2Se2O
by Xiaoning Sun, Pindu Chen, Xiaochun Wen and Hongxiang Chen
Crystals 2026, 16(1), 56; https://doi.org/10.3390/cryst16010056 - 13 Jan 2026
Viewed by 280
Abstract
Layered compounds containing the T2O plane (T = transition metal), which is the anti-type of the CuO2 plane in cuprate superconductors, have been explored widely because of their diverse physical properties. Among them, KV2Se2O has [...] Read more.
Layered compounds containing the T2O plane (T = transition metal), which is the anti-type of the CuO2 plane in cuprate superconductors, have been explored widely because of their diverse physical properties. Among them, KV2Se2O has attracted much attention due to its interesting physical properties, especially the magnetic order. In this work, we report a new isostructural chromium oxyselenide, RbCr2Se2O. It was synthesized using a solid-state method using Rb2CO3 as the source of Rb and O for the title compound, with the assistance of Ba. The compound crystallizes in the space group P4/mmm with lattice parameters a = 4.01123(8) Å and c = 7.49357(18) Å. Magnetic susceptibility measurements indicate an antiferromagnetic transition at 345 K for RbCr2Se2O and also above room temperature, as the Néel temperature is TN ≈ 400 K for KV2Se2O. The analysis of variable temperature XRD data reveals the anisotropic thermal expansion of the RbCr2Se2O lattice. The almost unchanged lattice parameter a near the transition temperature and the broad peak with an onset temperature of ~360 K in the differential scanning calorimetry data may have a relationship with the magnetic ordering. The measurement of electrical resistivity demonstrates the semiconducting behavior of RbCr2Se2O. The thermal activation model and variable-range hopping model are proposed to describe the conduction mechanism in the high- and low-temperature ranges, respectively. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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14 pages, 1962 KB  
Article
Impact of High Fe Doping on Structure, Optical, and Magnetic Properties of Zinc Oxide Nanostructures Synthesized by Hydrothermal Route
by Essam M. Abdel-Fattah and Salman M. Alshehri
Crystals 2026, 16(1), 55; https://doi.org/10.3390/cryst16010055 - 13 Jan 2026
Viewed by 305
Abstract
Zn1−xFexO nanocomposites (NCs) with varying Fe concentrations (x = 0, 0.1, 0.2, 0.3, and 0.4) were effectively prepared using the hydrothermal approach, and their morphology, structural, optical, and magnetic properties were systematically analyzed. XRD analysis confirmed Fe doping reduced [...] Read more.
Zn1−xFexO nanocomposites (NCs) with varying Fe concentrations (x = 0, 0.1, 0.2, 0.3, and 0.4) were effectively prepared using the hydrothermal approach, and their morphology, structural, optical, and magnetic properties were systematically analyzed. XRD analysis confirmed Fe doping reduced crystallinity and crystallite size. TEM images of Zn1−xFexO NCs exhibited smaller and more agglomerated nanostructures compared to the pure ZnO NPs. Raman and XPS analyses indicated increased lattice disorder, oxygen vacancies, and the coexistence of Fe2+/Fe3+ species. UV–Vis spectra showed enhanced visible light absorption and a tunable band gap, while PL results reflected defect-induced emission shifts and quenching, associated with zinc vacancies, interstitials, and oxygen-related defects. Magnetic measurements revealed a transition from diamagnetism to ferromagnetic-like behavior at room temperature for Fe content x ≥ 0.2, with magnetization strongly dependent on doping level. These results highlight Zn1−xFexO for advanced optoelectronic and spintronic applications. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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18 pages, 4965 KB  
Article
Research on Activation of Solid Waste Through Microbial Desilification
by Yuming Bai, Xiao Li, Limei Wu and Haiyang Qiao
Crystals 2026, 16(1), 54; https://doi.org/10.3390/cryst16010054 - 12 Jan 2026
Viewed by 194
Abstract
To investigate the biosilicification capabilities of Bacillus mucilaginosus and Bacillus polymyxa, silicon concentrations in supernatants from quartz and calcium silicate cultures were monitored over a 12-day period using inductively coupled plasma optical emission spectrometry (ICP-OES). Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), [...] Read more.
To investigate the biosilicification capabilities of Bacillus mucilaginosus and Bacillus polymyxa, silicon concentrations in supernatants from quartz and calcium silicate cultures were monitored over a 12-day period using inductively coupled plasma optical emission spectrometry (ICP-OES). Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to evaluate changes in the absorption intensity of Si–O–Si characteristic peaks, crystalline phase transformations in the reaction products, and the microstructural morphology of quartz and calcium silicate before and after microbial leaching. The results show that after leaching with B. mucilaginosus, the dissolved silicon concentration in the quartz supernatant reached a maximum of 73.868 mg/L on day 8. In contrast, following treatment with B. polymyxa, the silicon concentration in the calcium silicate supernatant peaked earlier, at 149.153 mg/L on day 4. After microbial leaching, both substrates exhibited marked changes in the intensity of the infrared absorption peaks at 1071 cm−1 and 1083 cm−1, suggesting the formation of Si–O–R type organosilicon complexes. Iron tailings (containing inert silica) and fly ash (containing active silica) were selected for experimental validation. Following treatment with B. mucilaginosus for desilication over an 8-day period, the activity index of iron tailings increased from 77.83% to 90.51%, while that of fly ash rose from 66.32% to 85.01%. ICP-OES analysis confirmed that under the action of B. mucilaginosus, the trends in silicon concentration and activity index in the supernatant of silica-containing solid wastes, such as iron tailings and fly ash, were consistent with those observed in quartz, thereby demonstrating effective biological desilication. These findings provide novel insights into the development of environmentally sound disposal methods for a wider range of solid waste types. Full article
(This article belongs to the Special Issue Synergizing Crystallography, Mineral Materials Science and Solid Waste Upcycling for Sustainable Materials Innovation)
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17 pages, 6554 KB  
Article
Further Insights into the Crystal Engineering of High Explosives of 1:2 Salts of the s-Tetrazine Receptor-Picrate Anion Series
by Matteo Savastano, María Dolores López de la Torre, Marco Pagliai, Giovanna Poggi, Francesca Ridi, Carla Bazzicalupi, Manuel Melguizo and Antonio Bianchi
Crystals 2026, 16(1), 53; https://doi.org/10.3390/cryst16010053 - 12 Jan 2026
Viewed by 312
Abstract
Both s-tetrazine and picric acid are widely known compounds in the realm of high-energy materials. We had previously taken an interest—mostly supramolecular, i.e., directed at the elucidation of lone pair–π interactions—in the crystal packing of phases containing s-tetrazine-based cations and picrate anions. Herein [...] Read more.
Both s-tetrazine and picric acid are widely known compounds in the realm of high-energy materials. We had previously taken an interest—mostly supramolecular, i.e., directed at the elucidation of lone pair–π interactions—in the crystal packing of phases containing s-tetrazine-based cations and picrate anions. Herein we report two novel compounds of this family: H2L4(picr)2 and (H2L5)2(picr)4; the former is a polymorph of a previously reported compound of a homologous host series (3,6-bis(4-morpholinobutyl)-1,2,4,5-tetrazine), the latter a salt of the commercially available 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine. The new phases were investigated via XRD: main interactions, crystal packing, and potential slip planes are discussed. Thermal analysis (DSC/TGA) was conducted for L5 and (H2L5)2(picr)4. Enthalpies of formation (thermochemical cycles/DFT) and in silico explosion parameters (EXPLO5) are reported for all compounds. Overall, the data herein reported improve the understanding of the correlation among supramolecular/packing details and the resulting explosive properties. Full article
(This article belongs to the Special Issue Co-Crystals and Polymorphic Transition in Energetic Materials)
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23 pages, 3143 KB  
Article
Influence of Deposition Temperature on the Mechanical and Tribological Properties of Cr/Ni Co-Doped Diamond-like Carbon Films
by Hassan Zhairabany, Hesam Khaksar, Edgars Vanags, Anatolijs Šarakovskis, Enrico Gnecco and Liutauras Marcinauskas
Crystals 2026, 16(1), 52; https://doi.org/10.3390/cryst16010052 - 12 Jan 2026
Viewed by 242
Abstract
This study aimed to examine the influence of sputtering temperature on the bonding structure and properties of non-hydrogenated chromium/nickel co-doped diamond-like carbon (DLC) films synthesized via direct current magnetron sputtering. The Cr/Ni doping levels in the coatings were regulated by varying the shield [...] Read more.
This study aimed to examine the influence of sputtering temperature on the bonding structure and properties of non-hydrogenated chromium/nickel co-doped diamond-like carbon (DLC) films synthesized via direct current magnetron sputtering. The Cr/Ni doping levels in the coatings were regulated by varying the shield opening above a chromium-nickel (20/80 at.%) target, resulting in a total metal co-doping concentration ranging from 6.1 to 8.9 at.%. The thickness of the Cr/Ni-DLC films ranged from 160 to 180 nm. Meanwhile, the deposition temperatures of 185 °C and 235 °C were achieved by adjusting the substrate-to-target distance. The XPS and Raman spectroscopy results indicated enhanced graphitization of the Cr/Ni-DLC films with a decrease in the synthesis temperature. XPS results indicated the formation of carbon-oxide and metal-oxide bonds, with no evidence of metal carbide formation in the doped DLC films. Furthermore, both the nanohardness and Young’s modulus demonstrated significant improvement, while the friction coefficient was reduced more than twice as the deposition temperature increased. These findings provide valuable insights into the influence of deposition temperature on Cr/Ni co-doped DLC films, highlighting their potential as advanced functional coatings. Full article
(This article belongs to the Special Issue Functional Thin Films: Growth, Characterization, and Applications)
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10 pages, 1831 KB  
Article
Electrodeposition and Corrosion Resistance of Ni-Mo Alloy Coating: Effect of Electroplating Bath pH Values
by Xi Shi, Shiyuan Zhu, Qiongyu Zhou, Bo Liang, Jun Li, Guangji Li, Longquan Chen and Peijun Xu
Crystals 2026, 16(1), 51; https://doi.org/10.3390/cryst16010051 - 11 Jan 2026
Viewed by 431
Abstract
Ni-Mo alloy coating has shown exciting potential as a candidate to replace chromium coating. In this paper, Ni-Mo alloy coatings were successfully electrodeposited from a citrate/ammonia bath, and the effect of the bath pH values over a wide range (4–10) on the characteristics [...] Read more.
Ni-Mo alloy coating has shown exciting potential as a candidate to replace chromium coating. In this paper, Ni-Mo alloy coatings were successfully electrodeposited from a citrate/ammonia bath, and the effect of the bath pH values over a wide range (4–10) on the characteristics and corrosion resistance of Ni-Mo alloy coating was studied in detail. Results show that all the deposited Ni-Mo alloy coatings consist of a crystalline solid-solution Ni(Mo) fcc structure. An increase in bath pH values could facilitate the deposition of Mo, thereby increasing the Mo content and decreasing the crystallite size of Ni-Mo alloy coatings. However, there are subtle gaps between the coarse grains on the surface of the Ni-Mo alloy coating deposited at pH 10. These subtle gaps tend to form between the coarse grains on the surface of the electrodeposited Ni-Mo alloy coating because of the relatively high Mo content, refined grains, and appropriate morphology. The Ni-Mo alloy coating deposited at pH 9 exhibits optimal corrosion resistance, attributed to its lowest corrosion current density icorr (7.31 × 10−6 A cm−2), the strongest polarization resistance (11.13 kΩ·cm−2), and impedance value, which are mainly contributed to by the coating resistance and charge-transfer resistance. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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23 pages, 8282 KB  
Article
Investigation of Copper as Collector Metal in Sodium-Oxide Fluxed Aluminothermic Reduction of Manganese Ore
by Theresa Coetsee and Frederik De Bruin
Crystals 2026, 16(1), 50; https://doi.org/10.3390/cryst16010050 - 11 Jan 2026
Cited by 1 | Viewed by 296
Abstract
Aluminothermic reduction is gaining renewed interest as an alternative processing route for the circular economy. A unique Na2O-fluxed MnO2 ore formulation with a small quantity of carbon reductant was applied to ensure rapid pre-reduction to MnO. This approach negates the [...] Read more.
Aluminothermic reduction is gaining renewed interest as an alternative processing route for the circular economy. A unique Na2O-fluxed MnO2 ore formulation with a small quantity of carbon reductant was applied to ensure rapid pre-reduction to MnO. This approach negates the pre-roasting step. The Na2O flux enables the formation of the water-soluble compound, NaAlO2, which enables recycling of Al2O3 for aluminium production. The addition of copper as a collector metal improved the overall alloy yield from 43% to 57%, which includes a 6% increase in Mn recovery to the alloy. The product alloy is a medium-carbon Fe–Mn–Si–Al–Cu complex ferroalloy that can be used as a steelmaking ferroalloy additive. The ferroalloy consists of 54% Mn, 19% Fe, 2.1% Si, 2.6% Al, 21% Cu, and 1.2% C. This carbon content is modulated by low-carbon solubility copper, despite the use of a graphite crucible. The formulated slag exhibits high Al2O3 solubility, enabling effective alloy–slag separation from the high Al2O3 content slag of 52% Al2O3. Gas–slag–metal equilibrium calculations for 1650 °C–1950 °C overlap with the experimentally produced alloy chemistry in %C and %Si, but not the %Al, as the uptake of aluminium exceeds the equilibrium calculation at 0.03–0.17%. Full article
(This article belongs to the Special Issue Exploring New Materials for the Transition to Sustainable Energy)
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16 pages, 6941 KB  
Article
Microstructural, Corrosion and Mechanical Properties of Ni–Al–Cr/SiC Coatings on Inconel 600 Deposited by Arc Welding
by Tayfun Çetin
Crystals 2026, 16(1), 49; https://doi.org/10.3390/cryst16010049 - 11 Jan 2026
Viewed by 303
Abstract
In this study, the microstructural, mechanical, wear, and corrosion behavior of Ni-Al-Cr and Ni–Al–Cr/SiC composite coatings with different composition ratios, produced by electric arc melting on Inconel 600 substrates, was systematically investigated. Microhardness measurements revealed a significant and consistent increase in the hardness [...] Read more.
In this study, the microstructural, mechanical, wear, and corrosion behavior of Ni-Al-Cr and Ni–Al–Cr/SiC composite coatings with different composition ratios, produced by electric arc melting on Inconel 600 substrates, was systematically investigated. Microhardness measurements revealed a significant and consistent increase in the hardness values of the coatings depending on the increase in SiC reinforcement ratio (1%, 3%, and 5%). Wear tests showed that the coated samples exhibited significantly higher wear resistance compared to the pure Inconel 600 substrate. A significant improvement in wear resistance was achieved with the addition of SiC at 1% and 3% weight percentages; the width and depth of wear tracks were significantly reduced with SiC reinforcement. In contrast, increasing the SiC ratio to 5% weight percentage led to a decrease in wear resistance. This was attributed to particle aggregation at high SiC content, weakening of bonds at the matrix-reinforcement interface, and the behavior of SiC particles separated from the matrix as third-body abrasives. Electrochemical corrosion tests have shown that SiC-reinforced coatings form a more stable and permanent passive film, and corrosion resistance increases as the SiC content increases (1%, 3%, and 5%). The results indicate that the SiC reinforcement ratio affects the mechanical and electrochemical properties of Ni-Al-Cr/SiC composite coatings produced by electric arc melting. Full article
(This article belongs to the Special Issue Microstructure Analysis, Phase Composition and Properties of Metal)
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