Crystals

19 pages, 3038 KB

Open AccessArticle

Design, Preparation and Synergistic Optimization of Mechanical Properties and Thermal Neutron Shielding Performance of Mg-Dy-Sm-Zr Alloys

by Huabing Lu, Chengzhi Duan, Enci Niu, Xiyu Xu, Jia She, Jun Tan, Wei Zhang and Jianjun Mao

Crystals 2025, 15(10), 894; https://doi.org/10.3390/cryst15100894 (registering DOI) - 15 Oct 2025

Abstract

Addressing the challenge of synergistically optimizing shielding performance and mechanical properties in nuclear radiation shielding materials, this study designed and prepared as-cast Mg-12Dy-xSm-0.4Zr (x = 1, 2, 3) alloys by incorporating rare earth elements Dy and Sm, which possess high thermal neutron absorption [...] Read more.

Addressing the challenge of synergistically optimizing shielding performance and mechanical properties in nuclear radiation shielding materials, this study designed and prepared as-cast Mg-12Dy-xSm-0.4Zr (x = 1, 2, 3) alloys by incorporating rare earth elements Dy and Sm, which possess high thermal neutron absorption cross-sections. The co-addition of Sm and Dy significantly refined the grains and promoted the precipitation of bone-like Mg₅(Sm,Dy) and Mg₄₁Sm₅ phases along grain boundaries. The alloys exhibited favorable mechanical properties, with ultimate tensile strength (UTS) reaching up to 194.6 MPa and elongation (EL) up to 10.9%. However, higher Sm content led to an increased amount of secondary phases at grain boundaries, resulting in stress concentration and a subsequent decline in both yield strength and elongation. Moreover, the combined addition of Dy and Sm markedly enhanced the thermal neutron shielding performance. Experimental results agreed well with Geant4 simulations, showing that both the neutron shielding rate and linear attenuation coefficient improved with increasing Sm content, demonstrating the positive role of Dy and Sm in neutron absorption. The developed alloy achieves simultaneous improvement in mechanical properties and neutron shielding capacity, providing valuable insights for the development of lightweight “function–structure integrated” radiation shielding materials for applications such as nuclear medicine and aerospace. Full article

(This article belongs to the Special Issue Microstructure Characterization and Design of Advanced Alloys)

16 pages, 1743 KB

Open AccessArticle

Automated and Selective Product Removal for Lab-Scale Draft Tube Baffle Crystallizer Under Vacuum Operation

by Laura Marsollek, Merlin Hubmann, Kim Buchhorn and Norbert Kockmann

Crystals 2025, 15(10), 893; https://doi.org/10.3390/cryst15100893 (registering DOI) - 15 Oct 2025

Abstract

Continuous product removal in lab-scale vacuum applications poses significant challenges, particularly due to the risk of clogging in the product tube caused by the small tubing diameter relative to the particle size. This contribution addresses this problem by presenting an automatic gate system [...] Read more.

Continuous product removal in lab-scale vacuum applications poses significant challenges, particularly due to the risk of clogging in the product tube caused by the small tubing diameter relative to the particle size. This contribution addresses this problem by presenting an automatic gate system specifically designed for selective product removal within a Draft Tube Baffle Crystallizer (DTBC). In order to enable selective product removal, the classification behavior of the crystals in the DTBC was evaluated in experimental studies by determining the crystal size distributions in the product removal and in the fine grain dissolution. The influence of different stirring speeds and solid contents were considered for different product removal rates. The results indicated that sufficient classification occurs at stirring speeds of 600 rpm and a crystal content of ≥3 wt%. Under these conditions, more than 75% of the crystals in the product were larger than 210 μm from a sieve size range of 45 to 500 µm. During experiments, the automatic gate system allowed for blockage-free, continuous product removal for six hours per experiment and more than thirty hours in total, proving the reliability of the system. Although designed for down-scaling of the DTBC, this system can also be applied to other continuous-flow lab-scale applications. Full article

(This article belongs to the Section Crystal Engineering)

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21 pages, 4436 KB

Open AccessArticle

Activated Carbon–Geopolymer Composites: Influence of Particle Size and Content on CO₂ Adsorption and Mechanical and Thermal Properties

by Daniela Řimnáčová, Ivana Perná, Martina Novotná, Monika Šupová, Martina Nováková and Olga Bičáková

Crystals 2025, 15(10), 892; https://doi.org/10.3390/cryst15100892 (registering DOI) - 15 Oct 2025

Abstract

This study aims to develop and characterize innovative geopolymer composites by incorporating activated carbon into a geopolymer matrix to create a novel, effective sorption material suitable for non-dusty or medium-temperature environmental applications. Specifically, it examines the impact of using a single source of [...] Read more.

This study aims to develop and characterize innovative geopolymer composites by incorporating activated carbon into a geopolymer matrix to create a novel, effective sorption material suitable for non-dusty or medium-temperature environmental applications. Specifically, it examines the impact of using a single source of activated carbon, both in its original granular form and milled form, at two different loading levels for each. The research focuses on evaluating how these variations influence the textural, adsorption, mechanical, and thermal properties of the resulting geopolymer composites, with particular attention to strength and thermal stability under operational conditions. The CO₂ adsorption capacity of the composites measured at 25 °C and pressure up to 0.1 MPa varied from 48.8 to 60.0 mg.g⁻¹, with the highest performance observed at a lower content of the granular form, while commercial pure activated carbon reached 120.8 mg.g⁻¹. However, incorporation of a granular form negatively affected thermal stability (approximately 20 wt.% weight loss) and significantly reduced compressive strength (below 45 MPa) due to increased material inhomogeneity. Despite these limitations, both types of composites show promising potential for environmental applications. However, further optimization is required to balance sorption capacity, strength, and thermal stability. Full article

(This article belongs to the Section Macromolecular Crystals)

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Graphical abstract

19 pages, 5326 KB

Open AccessArticle

Preparation of Temperature-Responsive Janus Nanosheets and Their Application in Emulsions

by Yue Gao, Xuan Qi, Hao Yan, Dan Xue, Xuefeng Xu, Suixin He, Wei Xia and Junfeng Zhang

Crystals 2025, 15(10), 891; https://doi.org/10.3390/cryst15100891 (registering DOI) - 15 Oct 2025

Abstract

In this study, patch-structured C₈/CHO template microspheres were successfully synthesized through in situ reduction and sol–gel reactions, providing a reusable platform for subsequent modifications. Based on these templates, temperature-responsive PW₁₂O₄₀³⁻-PILs/PNIPAM Janus nanosheets were prepared via sequential [...] Read more.

In this study, patch-structured C₈/CHO template microspheres were successfully synthesized through in situ reduction and sol–gel reactions, providing a reusable platform for subsequent modifications. Based on these templates, temperature-responsive PW₁₂O₄₀³⁻-PILs/PNIPAM Janus nanosheets were prepared via sequential Schiff-base coupling and ATRP. Structural characterizations (XRD, SEM, TEM, FTIR, and TGA) confirmed successful functionalization and nanosheet formation. The PNIPAM moiety endowed the nanosheets with temperature responsiveness, while the incorporation of polymerized ionic liquids and phosphotungstate anions further enhanced amphiphilicity and dispersion stability. When applied as particulate emulsifiers in water/toluene systems, the Janus nanosheets formed stable Pickering emulsions at elevated temperatures and underwent reversible emulsification–demulsification upon temperature cycling. These findings demonstrate the potential of PW₁₂O₄₀³⁻-PILs/PNIPAM Janus nanosheets as smart emulsifiers for responsive separation and formulation technologies. Full article

(This article belongs to the Section Macromolecular Crystals)

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21 pages, 5374 KB

Open AccessArticle

Barium Carbonate Synthesized via Hydrolysis: Morphostructural Analysis and Photocatalytic Performance in Polymer and Geopolymer Matrices

by Adriana-Gabriela Schiopu, Maria-Ionela Popescu, Chaima Assamadi, Ecaterina Magdalena Modan, Sorin Georgian Moga, Denis Aurelian Negrea, Mihai Oproescu, Soumia Aboulhrouz, Hakima Aouad and Miruna-Adriana Ioța

Crystals 2025, 15(10), 890; https://doi.org/10.3390/cryst15100890 (registering DOI) - 15 Oct 2025

Abstract

Barium carbonate (BaCO₃) nanoparticles were synthesized by a facile hydrolysis route using BaCl₂ and KOH in aqueous solution, with atmospheric CO₂ as the carbonate source, without external agents. Their structural and morphological properties were investigated by XRD, ATR-FTIR, SEM, [...] Read more.

Barium carbonate (BaCO₃) nanoparticles were synthesized by a facile hydrolysis route using BaCl₂ and KOH in aqueous solution, with atmospheric CO₂ as the carbonate source, without external agents. Their structural and morphological properties were investigated by XRD, ATR-FTIR, SEM, and BET, confirming the formation of a pure orthorhombic witherite phase with rod-like morphology and different surface specific areas. The crystallite size increased from 52 to 86 nm with higher precursor concentration and synthesis temperature, as predicted by a regression model correlating synthesis parameter with particle growth. When incorporated into polymer (PVC) and geopolymer (GP) matrices, BaCO₃ enhanced the photocatalytic degradation of methylene blue (MB) under solar light, with GP@Nano-BaCO₃ achieving a higher rate constant compared to PVC@Nano-BaCO₃. The results highlight that the synthesis strategy yields well-defined BaCO₃ nanoparticles with tunable structural features and promising photocatalytic potential when integrated in functional polymer matrices. Future work will address doping strategies and testing in real wastewater conditions. Overall, this synthesis strategy offers a reproducible and environmentally friendly route to BaCO₃ nanoparticles with potential applications in hybrid materials for visible light-driven environmental remediation. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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20 pages, 3712 KB

Open AccessArticle

LiCl@C-BMZIF Porous Composites: Synthesis, Structural Characterization, and the Effects of Carbonization Temperature and Salt Loading on Thermochemical Energy Storage

by Fuyao Zhang, Wenjing Wei, Quanrong Fang and Xianfeng Fan

Crystals 2025, 15(10), 889; https://doi.org/10.3390/cryst15100889 (registering DOI) - 14 Oct 2025

Abstract

To address the imbalance in energy supply and demand across different regions and seasons, the thermochemical conversion process was selected to efficiently utilize surplus energy. In the search for suitable novel materials, this study developed a porous matrix “in-salt” composite using a carbonized [...] Read more.

To address the imbalance in energy supply and demand across different regions and seasons, the thermochemical conversion process was selected to efficiently utilize surplus energy. In the search for suitable novel materials, this study developed a porous matrix “in-salt” composite using a carbonized metal-organic framework as the carrier and LiCl as the primary reactant. When exposed to water vapor, the innovative material enabled both adsorption and desorption of water vapor, leading to the release and storage of thermal energy, thereby achieving effective energy storage. Using Zn(NO₃)₂·6H₂O and Co(NO₃)₂·6H₂O as metal ion sources and 2-methylimidazole as the ligand, bimetallic zeolitic imidazolate frameworks (BMZIFs) were fabricated via the liquid-phase precipitation method. The composite specimen prepared at a carbonization temperature of 1000 °C with a 20% LiCl mass concentration exhibited the most promising thermal storage performance, achieving the highest capacity, with a final water loss of 53.56% and a stable water adsorption capacity of about 0.831 g·g⁻¹. Full article

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

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12 pages, 5008 KB

Open AccessArticle

Creation of Modified Aluminum Powders with Increased Reactivity for Energy Systems

by Ayagoz E. Bakkara, Ainur S. Khairullina, Aida B. Artykbayeva, Alua E. Maten, Aizhan O. Nugymanova, Anar O. Zhapekova and Bakhtiyar S. Sadykov

Crystals 2025, 15(10), 888; https://doi.org/10.3390/cryst15100888 (registering DOI) - 14 Oct 2025

Abstract

Aluminium plays a key role in developing modern energy technologies, from electrical systems to high-energy materials, providing a combination of functionality, economy, and reliability, but the oxide film on its particles reduces the effective reactivity. This work aims to increase the reactivity of [...] Read more.

Aluminium plays a key role in developing modern energy technologies, from electrical systems to high-energy materials, providing a combination of functionality, economy, and reliability, but the oxide film on its particles reduces the effective reactivity. This work aims to increase the reactivity of aluminum powder by mechanochemical treatment using modifiers. The materials used were aluminum powder of the ASD brand and graphite of the GL-1 brand. The experiment subjected aluminum powder to mechanochemical treatment (MCT) with different graphite contents. It was shown that MCT significantly increases active aluminum content in the powder due to partial destruction of the oxide film on its surface. In addition, morphological analyses confirm the destruction of the oxide, the graphite coating, and the appearance of lamellar structures measuring 0–58 µm. Thermal analysis shows that the primary exothermic peak shifts from 662.6 °C to 653.9 °C for Al + 10% graphite, and the heat released increases by 27%, which means lower activation energy and more complete oxidation. However, at 20% graphite, the thermal gain decreases, since carbon shields the metal areas. Thus, the optimal content is 10% graphite: at this ratio, the best thermochemical behavior of the powder is achieved. The data obtained indicate that the MCT of aluminum powder with graphite effectively increases its reactivity. The resulting aluminum powders with modified particle surfaces facilitate the development of new technologies for the creation of various high-energy solid propellant systems. For rocket engines, preference is given to solid rocket propellant (SRP), which is a mixture of substances (components) capable of burning in the absence of air, producing a large amount of gaseous working fluid heated to a high temperature, providing thrust. Full article

(This article belongs to the Section Hybrid and Composite Crystalline Materials)

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22 pages, 4727 KB

Open AccessPerspective

Carbon Nanotube Production Pathways: A Review of Chemical Vapor Deposition and Electrochemical CO₂ Conversion, Such as C2CNT

by Gad Licht and Stuart Licht

Crystals 2025, 15(10), 887; https://doi.org/10.3390/cryst15100887 (registering DOI) - 14 Oct 2025

Abstract

Graphene Nano-Carbons (GNCs) have a huge potential, but current production methods limit their exploration and use. Many GNCs will be explored here with a focus on CNTs (Carbon NanoTubes) (which have some of the highest strengths of any known material, conductivity, EMF absorptivity, [...] Read more.

Graphene Nano-Carbons (GNCs) have a huge potential, but current production methods limit their exploration and use. Many GNCs will be explored here with a focus on CNTs (Carbon NanoTubes) (which have some of the highest strengths of any known material, conductivity, EMF absorptivity, and many other useful properties. Manufacturing them abundantly, inexpensively, and in eco-friendly ways remains a significant challenge. Two CNT/GNCs production methods are compared and reviewed. Traditional Chemical Vapor Deposition (CVD) production heats organic reactants with metal catalysts to form GNC/CNTs. As of now, the CVD CNT production has been limited by the high-energy costs, costs per weight comparable to precious metals, and a high CO₂-footprint. C2CNT is an electrochemical methodology that overcomes the constraints of CVD, while producing high-quality CNT/GNCs. C2CNT is a molten carbonate CO₂-electrolysis that makes GNCs. The C2CNT process also selectively produces a wider variety of CNTs (including helical, magnetic, and doped) and GNCs with higher product specificity than CVD by fine-tuning electrolysis parameters. The wide variety of CNTs/GNCs that can be produced by each of these methods is reviewed and discussed. The goal of this perspective is to compare GNC production methods. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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15 pages, 3607 KB

Open AccessArticle

Photo-Responsive Brominated Hydrogen-Bonded Liquid Crystals

by Christian Anders, Tejal Nirgude, Ahmed F. Darweesh and Mohamed Alaasar

Crystals 2025, 15(10), 886; https://doi.org/10.3390/cryst15100886 (registering DOI) - 14 Oct 2025

Abstract

This study reports on the preparation and comprehensive characterisation of new brominated hydrogen-bonded liquid crystalline (HBLC) materials. Two distinct series of supramolecular complexes were prepared by hydrogen-bond formation between 3-bromo-4-pentyloxybenzoic acid as the proton donor and non-fluorinated and fluorinated azopyridines with variable terminal [...] Read more.

This study reports on the preparation and comprehensive characterisation of new brominated hydrogen-bonded liquid crystalline (HBLC) materials. Two distinct series of supramolecular complexes were prepared by hydrogen-bond formation between 3-bromo-4-pentyloxybenzoic acid as the proton donor and non-fluorinated and fluorinated azopyridines with variable terminal chains as proton acceptors. The successful formation of a hydrogen bond was confirmed by FTIR spectroscopy. The impact of alkyl chain length and fluorination on the mesomorphic properties of the HBLCs was systematically investigated. The molecular self-assembly was thoroughly examined using polarised optical microscopy (POM) and differential scanning calorimetry (DSC), revealing the presence of smectic C (SmC), smectic A (SmA), and nematic (N) phases, with thermal stability being highly dependent on the molecular architecture. Notably, the introduction of fluorine atoms significantly influenced the phase transition temperatures and the overall mesophase range. Using bromine as a lateral substituent induces the formation of SmC phases in these HBLCs, a feature absent in their non-brominated analogues. Further structural insights were obtained through X-ray diffraction (XRD) investigations, confirming the nature of the observed LC phases. Additionally, the photo-responsive characteristics of these HBLCs were explored via UV-Vis spectroscopy, demonstrating their ability to undergo reversible photoisomerisation upon light irradiation. These findings underscore the critical role of precise molecular design in tailoring the properties of HBLCs for potential applications such as optical storage devices. Full article

(This article belongs to the Special Issue Thermotropic Liquid Crystals as Novel Functional Materials)

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10 pages, 3119 KB

Open AccessArticle

Printable Silicone-Based Emulsions as Promising Candidates for Electrically Conductive Glass-Ceramic Composites

by Annalaura Zilio and Enrico Bernardo

Crystals 2025, 15(10), 885; https://doi.org/10.3390/cryst15100885 (registering DOI) - 14 Oct 2025

Abstract

The Na₂O-SrO-SiO₂ system shows promise in the development of glasses that can be transformed into electrically conductive glass ceramics. The conventional processing of such materials usually involves the synthesis of a parent glass, followed by a complex devitrification treatment. This [...] Read more.

The Na₂O-SrO-SiO₂ system shows promise in the development of glasses that can be transformed into electrically conductive glass ceramics. The conventional processing of such materials usually involves the synthesis of a parent glass, followed by a complex devitrification treatment. This study proposes a simplified approach based on the use of preceramic polymers, namely silicone resins combined with oxide fillers. These systems yield silicate-based ceramics through direct heat treatment, replicating the phase assembly of traditional glass ceramics with no need for prior glass melting. A printable formulation was developed by mixing a silicone resin with an acrylate-based photocurable resin, sodium nitrate and strontium carbonate. The resulting ‘suspension-emulsion’ was later shaped into monolithic components using digital light processing. After pyrolysis in nitrogen atmosphere, the components transformed into SrSiO₃ crystals embedded in a composite matrix, in turn composed of glass and turbostratic carbon (the latter specifically offered by the silicone polymer). This combination of crystalline silicates and carbon resulted in measurable electrical conductivity. This study confirms that silicone-derived systems can serve as effective precursors for conductive glass-ceramic analogues, providing an alternative to conventional methods with single-step processing. This approach enables structural shaping through 3D printing and the development of functional properties suitable for electronic or electrochemical applications. Full article

(This article belongs to the Special Issue Advances in Glass-Ceramics)

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15 pages, 6721 KB

Open AccessArticle

Mechanical Behaviors of Copper Nanoparticle Superlattices: Role of Lattice Structure

by Jianjun Bian and Liang Yang

Crystals 2025, 15(10), 884; https://doi.org/10.3390/cryst15100884 - 13 Oct 2025

Abstract

Nanoparticle superlattices, periodic assemblies of nanoscale building blocks, offer opportunities to tailor mechanical behavior through controlled lattice geometry and interparticle interactions. Here, classical molecular dynamics simulations were performed to investigate the compressive responses of copper nanoparticle superlattices with face-centered cubic (FCC), hexagonal close-packed [...] Read more.

Nanoparticle superlattices, periodic assemblies of nanoscale building blocks, offer opportunities to tailor mechanical behavior through controlled lattice geometry and interparticle interactions. Here, classical molecular dynamics simulations were performed to investigate the compressive responses of copper nanoparticle superlattices with face-centered cubic (FCC), hexagonal close-packed (HCP), body-centered cubic (BCC), and simple cubic (SC) arrangements, as well as disordered assemblies. The flow stresses span 0.5–1.5 GPa. Among the studied configurations, the FCC and HCP superlattices exhibit the highest strengths (~1.5 GPa), followed by the disordered assembly (~1.0 GPa) and the SC structure (~0.8 GPa), while the BCC superlattice exhibits the lowest strength (~0.5 GPa), characterized by pronounced stress drops and recoveries resulting from interfacial sliding. Atomic-scale analyses reveal that plastic deformation is governed by two coupled geometric factors: (i) the number of interparticle contact patches, controlling the density of dislocation sources, and (ii) their orientation relative to the loading axis, which dictates stress transmission and slip activation. A combined parameter integrating particle coordination number and contact orientation is proposed to rationalize the structure-dependent strength, providing mechanistic insight into the deformation physics of metallic nanoparticle assemblies. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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21 pages, 3707 KB

Open AccessArticle

Synthesis, Crystal Structure and Optical Properties of Novel 1,10-Phenanthroline Derivatives Containing 2,6-Diisopropylphenoxy Substituents

by Martin Tsvetkov, Rumen Lyapchev, Mihail Kolarski, Bernd Morgenstern and Joana Zaharieva

Crystals 2025, 15(10), 883; https://doi.org/10.3390/cryst15100883 - 13 Oct 2025

Abstract

Two phenanthroline derivatives, 2-(2,6-diisopropylphenoxy)-9-phenyl-1,10-phenanthroline and 2,9-bis(2,6-diisopropylphenoxy)-1,10-phenanthroline, were synthesized. The unsymmetrical derivative was obtained in high yield through a sequence combining Suzuki coupling and nucleophilic substitution. The crystal structures of both compounds were determined by single-crystal X-ray diffraction and examined by Hirshfeld surface analysis, [...] Read more.

Two phenanthroline derivatives, 2-(2,6-diisopropylphenoxy)-9-phenyl-1,10-phenanthroline and 2,9-bis(2,6-diisopropylphenoxy)-1,10-phenanthroline, were synthesized. The unsymmetrical derivative was obtained in high yield through a sequence combining Suzuki coupling and nucleophilic substitution. The crystal structures of both compounds were determined by single-crystal X-ray diffraction and examined by Hirshfeld surface analysis, which outlined the main intermolecular interactions responsible for the packing. The optical properties were studied by UV–Vis absorption and fluorescence spectroscopy in different solvents. The unsymmetrical compound showed stronger intramolecular charge transfer and more pronounced solvatochromism, while the symmetrical analog had a higher fluorescence quantum yield and longer excited-state lifetime. These results demonstrate the role of substitution symmetry in controlling molecular organization and photophysical properties of phenanthroline derivatives, with relevance to sensing and optoelectronic applications. Full article

(This article belongs to the Section Organic Crystalline Materials)

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15 pages, 3572 KB

Open AccessArticle

Effects of Nd₂Fe₁₄B Powder Particle Size and Content on Microstructure and Properties of Nd₂Fe₁₄B_p/2024Al Composites

by Tao Qin, Qin Yang, Jincheng Yu, Bowen Fan, Ping Guo and Chenglong Ding

Crystals 2025, 15(10), 882; https://doi.org/10.3390/cryst15100882 - 13 Oct 2025

Abstract

In this article, a Nd₂Fe₁₄B_p/2024Al composite was prepared using high-energy ball milling, magnetic field cold isostatic pressing, and microwave sintering. The influence of powder particle size on microstructure and mechanical properties was discussed. The experimental results demonstrated [...] Read more.

In this article, a Nd₂Fe₁₄B_p/2024Al composite was prepared using high-energy ball milling, magnetic field cold isostatic pressing, and microwave sintering. The influence of powder particle size on microstructure and mechanical properties was discussed. The experimental results demonstrated that a ball milling duration of 10 h yielded powders with an average particle size of 5 μm, resulting in a refined and homogeneous microstructure, with a hardness value of 115 HV. Additionally, the densification process of the microwave-sintered sample was analyzed. When the sintering temperature was 490 °C, in-depth analysis was conducted on the effect of Nd₂Fe₁₄B addition on the microstructure and properties of the composite. The results showed that when the addition of Nd₂Fe₁₄B was 15 wt.%, the microstructure of the composite was uniform with fewer pores, and the Nd₂Fe₁₄B phase was evenly distributed on the matrix. At the same time, the compactness, microhardness, yield strength, and compressive strength of the composite also reached their optimal values, which were 94.3%, 136 HV, 190.5 MPa, and 248.9 MPa, respectively. When the addition of Nd₂Fe₁₄B reached 20 wt.%, the magnetic properties of the composite were slightly better than those of 15 wt.% Nd₂Fe₁₄B addition. However, based on the goal of preparing a high-magnetic and high-performance aluminum-based composite, considering the microstructure, mechanical properties, and magnetic properties comprehensively, it is believed that 15 wt.% is the optimal addition amount of Nd₂Fe₁₄B. Full article

(This article belongs to the Special Issue Microstructural Characterization and Property Analysis of Alloys)

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15 pages, 8005 KB

Open AccessArticle

Effect of the Activator B(OCH₃)₃ on the Microstructure and Mechanical Properties of Cu-Mn-Al Alloy Coating via CMT Cladding

by Jin Peng, Shihua Xie, Junhai Xia, Xingxing Wang, Zenglei Ni, Pei Wang and Nannan Chen

Crystals 2025, 15(10), 881; https://doi.org/10.3390/cryst15100881 - 13 Oct 2025

Abstract

This study investigates the fabrication of a Cu-Mn-Al alloy coating on 27SiMn steel using Cold Metal Transfer (CMT) technology with an innovative Ar-B(OCH₃)₃ mixed shielding gas, focusing on the effect of the gas flow rate (5–20 L/min). The addition of [...] Read more.

This study investigates the fabrication of a Cu-Mn-Al alloy coating on 27SiMn steel using Cold Metal Transfer (CMT) technology with an innovative Ar-B(OCH₃)₃ mixed shielding gas, focusing on the effect of the gas flow rate (5–20 L/min). The addition of B(OCH₃)₃ was found to significantly enhance process stability by improving molten pool wettability, resulting in a wider cladding layer (6.565 mm) and smaller wetting angles compared to pure Ar. Macro-morphology analysis identified 10 L/min as the optimal flow rate for achieving a uniform and defect-free coating, while deviations led to oxidation (at low flow) or spatter and turbulence (at high flow). Microstructural characterization revealed that the flow rate critically governs phase evolution, with the primary κI phase transforming from dendritic/granular to petal-like/rod-like morphologies. At higher flow rates (≥15 L/min), increased stirring promoted Fe dilution from the substrate, leading to the formation of Fe-rich intermetallic compounds and distinct spherical Fe phases. Consequently, the cladding layer obtained at 10 L/min exhibited balanced and superior properties, achieving a maximum shear strength of 303.22 MPa and optimal corrosion resistance with a minimum corrosion rate of 0.02935 mm/y. All shear fractures occurred within the cladding layer, demonstrating superior interfacial bonding strength and ductile fracture characteristics. This work provides a systematic guideline for optimizing shielding gas parameters in the CMT cladding of high-performance Cu-Mn-Al alloy coatings. Full article

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18 pages, 2751 KB

Open AccessArticle

Assessment of the Influence of Chemical Composition, Atomic Distribution, and Grain Boundaries on Heat Transfer in Refractory High-Entropy Alloys Hf–Nb–Ta–Zr Based on Atomistic Simulation

by Rita I. Babicheva, Arseny M. Kazakov and Elena A. Korznikova

Crystals 2025, 15(10), 880; https://doi.org/10.3390/cryst15100880 - 13 Oct 2025

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Abstract

This work investigates the influence of chemical composition, grain boundary (GB) type, and atomic distribution on the thermal conductivity of Hf–Nb–Ta–Zr refractory high-entropy alloys (RHEAs) via atomistic simulations. Three compositions—equiatomic HfNbTaZr (M1), Hf₁₀Nb₄₀Ta₁₀Zr₄₀ (M2), and Hf [...] Read more.

This work investigates the influence of chemical composition, grain boundary (GB) type, and atomic distribution on the thermal conductivity of Hf–Nb–Ta–Zr refractory high-entropy alloys (RHEAs) via atomistic simulations. Three compositions—equiatomic HfNbTaZr (M1), Hf₁₀Nb₄₀Ta₁₀Zr₄₀ (M2), and Hf₄₀Nb₁₀Ta₄₀Zr₁₀ (M3)—were studied in single-crystalline and bicrystalline models containing Σ3 or Σ5 GBs. The effect of chemical short-range order (SRO) and GB segregation was probed by comparing results for non-relaxed structures with those obtained for corresponding materials relaxed using combined Monte Carlo/molecular dynamics (MC/MD) simulation. Material relaxation is accompanied by the formation of coherent nanoclusters (NbTa in M1, Nb or Zr in M2, Hf or Ta in M3) and Hf/Zr segregation to GBs. In single crystals, SRO reduces thermal conductivity by up to ~2.7% (e.g., from 3.66 to 3.56 W/m·K in M1), which is explained by the phonon scattering effect from matrix–cluster interfaces, densely distributed in the structures. In contrast, in certain bicrystals, the combined effects of GB healing and intragranular cluster coarsening lead to a 6.9% increase in thermal conductivity (from 4.59 to 4.93 W/m·K), despite the presence of high-energy Σ5 GBs. These results demonstrate that the interplay between SRO, GB segregation, and microstructural evolution governs phonon transport in RHEAs, revealing a counterintuitive pathway to enhance thermal conductivity through controlled atomic redistribution. Full article

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

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13 pages, 7105 KB

Open AccessArticle

Surface–Volume Integral Formulation for Evaluating Magnetization Losses in CORC^® Cables

by Francesco Lucchini and Fabrizio Dughiero

Crystals 2025, 15(10), 879; https://doi.org/10.3390/cryst15100879 - 12 Oct 2025

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Abstract

Modeling the electromagnetic (EM) behavior of CORC^® cables presents significant computational challenges due to the coexistence of thin superconducting tapes and thick structural formers. This creates a strongly multiscale problem, making traditional FEM-based approaches cumbersome, as they require extremely fine meshes to [...] Read more.

Modeling the electromagnetic (EM) behavior of CORC^® cables presents significant computational challenges due to the coexistence of thin superconducting tapes and thick structural formers. This creates a strongly multiscale problem, making traditional FEM-based approaches cumbersome, as they require extremely fine meshes to accurately resolve the different geometric scales. Integral Equation Methods (IEMs), on the other hand, are well-suited for magnetization loss analysis in multiscale superconducting structures, as they avoid modeling non-EM-active parts of the domain. This greatly reduces the effort involved in meshing the computational domain. In this work, we propose an IEM that couples surface and volumetric models to perform transient nonlinear analysis of CORC^®-like superconducting cables. Full article

(This article belongs to the Special Issue Superconductivity and Condensed Matter Physics)

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15 pages, 5057 KB

Open AccessArticle

Study on Preparation and Properties of Industrial Lignin Metallized Pellets for Ironmaking

by Dongwen Xiang, He Guo, Qiang Zhang, Guoqing Wu, Yajie Wang, Dong Li, Qinghua Zhang and Huaxin Hu

Crystals 2025, 15(10), 878; https://doi.org/10.3390/cryst15100878 - 11 Oct 2025

Viewed by 158

Abstract

The pulp and paper industry produces a large amount of industrial lignin as biomass waste every year and it is not effectively utilized, resulting in a waste of resources. In this paper, by exploring the influencing factors of the strength of industrial lignin [...] Read more.

The pulp and paper industry produces a large amount of industrial lignin as biomass waste every year and it is not effectively utilized, resulting in a waste of resources. In this paper, by exploring the influencing factors of the strength of industrial lignin green pellets and metallized pellets, it is expected that industrial lignin can be effectively applied to the ironmaking industry to achieve the purpose of energy saving and emission reduction. The results show that when the molar ratio of carbon to oxygen is 1.2, the falling strength and compressive strength of industrial lignin pellets can reach 6.8 times/0.5 m and 26.8 N, respectively. When the calcination temperature is 1100 °C, the compressive strength of industrial lignin metallized pellets reaches 78.5 N; when the roasting time is 60 min, the compressive strength of the industrial lignin metallized pellets is 865 N, and the metallization rate is 99.72%. It can meet the requirements of industrial production. Full article

(This article belongs to the Special Issue Metallurgy-Processing-Properties Relationship of Metallic Materials)

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8 pages, 5847 KB

Open AccessArticle

On-Demand Photopatterned Twisted Nematics for Generation of Polychromatic Vector Fields

by Edvard Grigoryan, Hayk H. Harutyunyan, Hrayr Hakobyan, Sergey A. Shvetsov, Tetiana Orlova, Mushegh Rafayelyan and Vahram L. Grigoryan

Crystals 2025, 15(10), 877; https://doi.org/10.3390/cryst15100877 - 11 Oct 2025

Viewed by 168

Abstract

A simple and efficient approach to spatially addressed polychromatic modulation of light polarization using a photopatterned nematic liquid crystal film is proposed and investigated. In particular, we demonstrate linear polarization structuring of the broadband probe beam, including the formation of polarization singularities under [...] Read more.

A simple and efficient approach to spatially addressed polychromatic modulation of light polarization using a photopatterned nematic liquid crystal film is proposed and investigated. In particular, we demonstrate linear polarization structuring of the broadband probe beam, including the formation of polarization singularities under the adiabatic propagation of linearly polarized light, which is achieved through in situ, rewritable photoalignment of nematic liquid crystal by a pump beam. This opto-optical control of polarization does not involve dynamic phase modulation and enables spatially resolved polarization patterning of broadband linearly polarized light in real time. Full article

(This article belongs to the Section Liquid Crystals)

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24 pages, 10080 KB

Open AccessArticle

Exploring Structural, Optoelectronic, Phonon, Spintronic, and Thermodynamic Properties of Novel Full-Heusler Compounds TiMCu₂ (M = Al, Ga, In): Eco-Friendly Materials for Next-Generation Renewable Energy Technologies

by Zeesham Abbas, Amna Parveen, H. I. Elsaeedy, Nejla Mahjoub Said and Mohd Taukeer Khan

Crystals 2025, 15(10), 876; https://doi.org/10.3390/cryst15100876 - 10 Oct 2025

Viewed by 204

Abstract

This work presents a comprehensive first-principles investigation of the structural, electronic, magnetic, optical, and thermodynamic properties of Ti-based full-Heusler compounds TiMCu₂ (M = Al, Ga, In). Using density functional theory within the GGA+U framework, the compounds were optimized and analyzed to evaluate [...] Read more.

This work presents a comprehensive first-principles investigation of the structural, electronic, magnetic, optical, and thermodynamic properties of Ti-based full-Heusler compounds TiMCu₂ (M = Al, Ga, In). Using density functional theory within the GGA+U framework, the compounds were optimized and analyzed to evaluate their stability and potential for functional applications. The results confirm robust structural and dynamic stability, as verified by elastic constants and phonon dispersion curves. All studied systems exhibit metallic character with pronounced spin polarization, while TiGaCu₂ shows the strongest total magnetization, highlighting its suitability for spintronic devices. Optical analyses reveal strong absorption across the visible and near-UV regions, low reflectivity, and favorable dielectric behavior, indicating promise for photovoltaic and optoelectronic applications. Thermodynamic modeling further confirms stability under high temperature and pressure, reinforcing their practical viability. Overall, the TiMCu₂ family demonstrates multifunctional characteristics, positioning them as eco-friendly and cost-effective candidates for next-generation renewable energy, spintronic, and optoelectronic technologies. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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20 pages, 3972 KB

Open AccessArticle

Optimization and Prediction of Mass Loss During Adhesive Wear of Nitrided AISI 4140 Steel Parts

by Ahmed Daghbouch, Borhen Louhichi and Mohamed Ali Terres

Crystals 2025, 15(10), 875; https://doi.org/10.3390/cryst15100875 - 10 Oct 2025

Viewed by 224

Abstract

Adhesive wear has been identified as a significant cause of material loss, representing a substantial challenge across diverse industrial sectors. In order to address this issue, it is imperative to conduct studies with the aim of mitigating this degradation. The present study focuses [...] Read more.

Adhesive wear has been identified as a significant cause of material loss, representing a substantial challenge across diverse industrial sectors. In order to address this issue, it is imperative to conduct studies with the aim of mitigating this degradation. The present study focuses on achieving a high-quality product with minimal mass loss during adhesive wear by utilizing gas nitriding treatment to optimize the wear parameters of AISI 4140 steel. The present study employed the Taguchi methodology and response surface methodology (RSM) in order to design the experiments. A comprehensive investigation was conducted into the key wear parameters, encompassing sliding speed (V), normal load (FN), and the microhardness of nitrided parts (HV). Furthermore, an artificial neural network (ANN) prediction model was developed to forecast the wear performance of 4140 Steel. The ANN model demonstrated an accuracy of approximately 99% when compared to the experimental data. In order to enhance the precision of wear estimation, prediction optimization was conducted using Bayesian and genetic algorithms. The findings demonstrated that the predicted R² values exhibited a reasonable alignment with the adjusted R² values, with a discrepancy of less than 0.2. The analysis demonstrated that the normal load is the most significant factor influencing wear, followed by hardness. In contrast, sliding speed was found to have the least significant impact. Full article

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

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15 pages, 4309 KB

Open AccessArticle

Interference of Sulphonate Buffering Agents with E. coli Hypoxanthine-Guanine Phosphoribosyltransferase Active Site Functioning: A Crystallographic and Enzymological Study

by Evgeniy A. Zayats, Yulia A. Abramchik, Maria A. Kostromina, Vladimir I. Timofeev, Mikhail B. Shevtsov, Alexey V. Mishin, Ilya V. Fateev, Andrey A. Karanov, Alexandra R. Sharafutdinova, Aleksandra O. Arnautova, Irina D. Konstantinova, Valentin I. Borshchevskiy and Roman S. Esipov

Crystals 2025, 15(10), 874; https://doi.org/10.3390/cryst15100874 - 8 Oct 2025

Viewed by 259

Abstract

The investigation of the structure–function relationship in hypoxanthine-guanine phosphoribosyltransferases (HGPRT) is a direction that is relevant for the development of drugs and approaches of enzymatic synthesis of modified nucleosides and nucleotides. This research paper is dedicated to the investigation of binding of sulphonate [...] Read more.

The investigation of the structure–function relationship in hypoxanthine-guanine phosphoribosyltransferases (HGPRT) is a direction that is relevant for the development of drugs and approaches of enzymatic synthesis of modified nucleosides and nucleotides. This research paper is dedicated to the investigation of binding of sulphonate molecules, such as HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) in the active sites of HGPRT and similar proteins. We report the crystal structure of HGPRT from Escherichia coli (EcoHGPRT) in a complex with HEPES. In the obtained X-ray structure, a HEPES molecule binds to the active site in a position that mimics one of the HGPRT substrates, namely phosphoribosylpyrophosphate (PRPP). Enzymological study has shown that HEPES is an inhibitor of EcoHGPRT, along with two structurally similar molecules, namely MES and PIPES. Comparison of the observed EcoHGPRT/HEPES complex to other reported structures in the context of inhibition study results provides an opportunity to explore the variety of binding modes of HEPES and similar molecules and to discuss the structure–function relationship in this enzyme and similar proteins. Full article

(This article belongs to the Special Issue Structure and Characterization of Enzymes)

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11 pages, 2186 KB

Open AccessArticle

A High-Performance Perovskite Solar Cell Prepared Based on Targeted Passivation Technology

by Meihong Liu, Yafeng Hao, Fupeng Ma, Pu Zhu, Huijia Wu, Ziwei Li, Wenyu Niu, Yujie Huang, Guitian Huangfu, Junye Li, Fengchao Li, Jiangang Yu, Tengteng Li, Longlong Zhang, Cheng Lei and Ting Liang

Crystals 2025, 15(10), 873; https://doi.org/10.3390/cryst15100873 - 8 Oct 2025

Viewed by 245

Abstract

Perovskite materials have garnered significant attention in both fundamental research and practical applications owing to their exceptional light absorption coefficients, low fabrication costs, and inherent advantages for thin-film and flexible device fabrication. Nevertheless, interface defects within perovskite films induce detrimental non-radiative carrier recombination [...] Read more.

Perovskite materials have garnered significant attention in both fundamental research and practical applications owing to their exceptional light absorption coefficients, low fabrication costs, and inherent advantages for thin-film and flexible device fabrication. Nevertheless, interface defects within perovskite films induce detrimental non-radiative carrier recombination and pronounced hysteresis effects, which collectively impose substantial limitations on the photovoltaic performance and long-term operational stability of perovskite solar cells (PSCs). Conventional passivation strategies, despite their demonstrated efficacy in mitigating interface defects, often inadvertently introduce secondary defects in originally defect-free regions, thereby restricting the extent of device performance improvement. To overcome this critical limitation, we have developed a precision defect passivation methodology that employs a targeted two-step immersion–cleaning process, achieving selective defect passivation while concomitantly eliminating residual passivating agents. This approach effectively prevents the formation of new defects in unaffected regions of the perovskite films, and the resultant PSC possesses a power conversion efficiency (PCE) of 21.08%, accompanied by a substantial mitigation of hysteresis behavior. Furthermore, unencapsulated devices demonstrate remarkable stability, retaining over 81% of their initial efficiency after 20 days of atmospheric storage under 50% relative humidity, which underscores the effectiveness of our passivation strategy in simultaneously enhancing both device performance and operational stability. Full article

(This article belongs to the Section Hybrid and Composite Crystalline Materials)

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9 pages, 2044 KB

Open AccessArticle

Particle Size and Dispersity Control in High-Quality Mid-Wave Infrared HgSe Quantum Dots

by Shuaipu Zang, Lingshi Wang, Kun Zhang, Jiaojiao Song, Lei Wang and Lin-Song Li

Crystals 2025, 15(10), 872; https://doi.org/10.3390/cryst15100872 - 8 Oct 2025

Viewed by 238

Abstract

Infrared HgSe quantum dots (QDs) enable mid-infrared and longer-wavelength infrared detection through intraband absorption, thereby expanding the selection range of traditional infrared detector materials, which holds promise for overcoming the challenges of complex fabrication processes and high costs. However, control of the size [...] Read more.

Infrared HgSe quantum dots (QDs) enable mid-infrared and longer-wavelength infrared detection through intraband absorption, thereby expanding the selection range of traditional infrared detector materials, which holds promise for overcoming the challenges of complex fabrication processes and high costs. However, control of the size and distribution of HgSe QDs is a key factor limiting the performance enhancement of infrared detectors. Here, the reaction temperatures, growth periods, and reactant stoichiometries of the precursors were systematically regulated to achieve high-quality HgSe QDs with sizes ranging from 2.42 nm to 7.54 nm and excellent monodispersity. Further ligand exchange and film formation tests indicate that this HgSe QD film exhibits excellent flatness. Consequently, the high-quality mid-infrared HgSe QDs reported here are anticipated to facilitate subsequent advancements in associated domains. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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17 pages, 9190 KB

Open AccessArticle

Mineralogical and Gemological Characteristics and Color Genesis of Zibai Jade

by Linhui Song, Mingyue He, Ziyun Zhang and Ling Yang

Crystals 2025, 15(10), 871; https://doi.org/10.3390/cryst15100871 - 8 Oct 2025

Viewed by 256

Abstract

Zibai Jade is a recently identified hydrogrossular-dominant jade originating from Shaanxi Province, China. It constitutes a polymineralic aggregate composed predominantly of hydrogrossular, with minor proportions of vesuvianite, diopside, chlorite, uvarovite, and calcite. A multi-method analytical approach was employed to characterize this jade, incorporating [...] Read more.

Zibai Jade is a recently identified hydrogrossular-dominant jade originating from Shaanxi Province, China. It constitutes a polymineralic aggregate composed predominantly of hydrogrossular, with minor proportions of vesuvianite, diopside, chlorite, uvarovite, and calcite. A multi-method analytical approach was employed to characterize this jade, incorporating conventional gemological testing, polarizing microscopy, SEM, XRD, BSE, XRF, and EPMA, as well as UV-Vis and infrared (IR). These techniques enabled a detailed examination of its mineralogy, surface features, and color origin. The stone displays a heterogeneous color distribution, featuring a base hue of light green to yellowish-green, accompanied by distinct occurrences of emerald-green spots, dark green spots, mossy green inclusions, white patches, white veinlets, and a black dot with a green ring. Microanalytical results indicate that the emerald-green spots are principally composed of uvarovite; the dark green spots are dominated by hydrogrossular, diopside, and chlorite; fibrous green inclusions consist mainly of chlorite and Cr-bearing grossular; white patches and veinlets are primarily composed of calcite; and the black dot with a green ring predominantly comprises chromite and uvarovite. Coloration is attributed to the combined influence of Fe and Cr³⁺. The formation of Zibai Jade involved three mineralization stages: deposition of a carbonate protolith, high-temperature metasomatism, and retrograde alteration. The metasomatism was driven by hydrothermal fluids derived from granodioritic and ultramafic rocks, which provided Si, Al, and the essential Cr, respectively. The interplay of these processes resulted in the development of Zibai Jade, which exhibits a dense texture and attractive coloration. Full article

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22 pages, 2773 KB

Open AccessArticle

Synthesis, Crystallographic Study and Antibacterial Activity of Ternary Copper(II) Complex with Chromone-Based Ligand and Pyridine

by Nikolina Filipović, Anamarija Stanković, Martina Medvidović-Kosanović, Dominik Goman, Stjepan Šarić, Goran Palijan and Tomislav Balić

Crystals 2025, 15(10), 870; https://doi.org/10.3390/cryst15100870 - 6 Oct 2025

Viewed by 355

Abstract

A new copper(II) complex was synthesized using chromone-2-carboxylic acid as the main ligand, and coordinated pyridine molecules. The complex was successfully crystallized and structurally characterized by single crystal X-ray diffraction. This revealed a mononuclear structure with a distorted square pyramidal geometry around the [...] Read more.

A new copper(II) complex was synthesized using chromone-2-carboxylic acid as the main ligand, and coordinated pyridine molecules. The complex was successfully crystallized and structurally characterized by single crystal X-ray diffraction. This revealed a mononuclear structure with a distorted square pyramidal geometry around the central Cu(II) ion. The coordination sphere comprises oxygen atoms from the chromone moiety and nitrogen atoms from pyridine, resulting in a five-coordinate complex. A comprehensive physicochemical characterization was performed using Fourier transform infrared spectroscopy (FT-IR), UV–Vis spectroscopy, elemental (C, H, N), electrochemical (CV) and thermal analysis (TGA/DSC) to confirm the coordination environment and thermal stability of the compound. The complex exhibits distinct spectroscopic features indicative of ligand–metal charge transfer and d–d transitions typical of Cu(II) species. In addition, the synthesized complex was subjected to antimicrobial screening against Gram-positive and Gram-negative bacteria. The compound showed promising antibacterial activity, particularly against Escherichia coli, indicating its potential as a bioactive coordination compound. These results contribute to the growing body of research on metal-based chromone derivatives and emphasize the importance of copper complexes for the development of new antibacterial agents with defined crystal structures. Full article

(This article belongs to the Special Issue Celebrating the 10th Anniversary of International Crystallography)

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13 pages, 1421 KB

Open AccessArticle

Structural Insights into Ni(II), Cu(II), and Zn(II) Coordination Complexes of Arylazoformamide and Arylazothioformamide Ligands

by Laxmi Tiwari, Jake Nelson and Kristopher V. Waynant

Crystals 2025, 15(10), 869; https://doi.org/10.3390/cryst15100869 - 4 Oct 2025

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Abstract

Understanding how redox-active ligands coordinate to metal centers of different oxidation states is essential for applications ranging from metal remediation and recycling to drug discovery. In this study, coordination complexes of nickel(II), copper(II), and zinc(II) chloride salts were synthesized by mixing the salts [...] Read more.

Understanding how redox-active ligands coordinate to metal centers of different oxidation states is essential for applications ranging from metal remediation and recycling to drug discovery. In this study, coordination complexes of nickel(II), copper(II), and zinc(II) chloride salts were synthesized by mixing the salts with either arylazoformamide (AAF) or arylazothioformamide (ATF) ligands in toluene or methanol. The AAF and ATF ligands coordinate through their 1,3-heterodienes, N=N–C=O and N=N–C=S, respectively, and, due to their known strong binding, the piperidine and pyrrolidine formamide units were selected, as was the electron-donating methoxy group on the aryl ring. A total of 12 complexes were obtained, representing potential chelation events from ligand-driven oxidation of zerovalent metals and/or coordination of oxidized metal salts. The X-ray crystallography revealed a range of coordination patterns. Notably, the Cu(II)Cl₂ complexes, in the presence of ATF, produce [ATF-CuCl]₂ dimers, supporting a potential reduction event at the copper, while other metals with ATF and all metals with AAF remain in the 2+ oxidation state. Hirshfeld analysis was performed on all complexes, and it was found that most interactions across the complexes were dominated by H…H, followed by Cl…H/H…Cl, with metals showing very little to no interaction with other atoms. Spectroscopic techniques such as UV–VIS absorption, NMR (when diamagnetic), and FTIR, in addition to electrochemical studies support the metal–ligand coordination. Full article

(This article belongs to the Special Issue Synthesis, Crystal Structures and Hirshfeld Surface Analysis of Coordination Compounds (3rd Edition))

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19 pages, 2329 KB

Open AccessArticle

Vortex Crystal Stabilized by the Competition Between Multi-Spin and Out-of-Plane Dzyaloshinskii–Moriya Interactions

by Satoru Hayami

Crystals 2025, 15(10), 868; https://doi.org/10.3390/cryst15100868 - 3 Oct 2025

Viewed by 387

Abstract

Multiple-Q magnetic states encompass a broad class of noncollinear and noncoplanar spin textures generated by the superposition of spin density waves. In this study, we theoretically explore the emergence of vortex crystals formed by multiple-Q spin density waves on a two-dimensional [...] Read more.

Multiple-Q magnetic states encompass a broad class of noncollinear and noncoplanar spin textures generated by the superposition of spin density waves. In this study, we theoretically explore the emergence of vortex crystals formed by multiple-Q spin density waves on a two-dimensional triangular lattice with

D_{3 h}

point group symmetry. Using simulated annealing applied to an effective spin model, we demonstrate that the synergy among the easy-plane single-ion anisotropy, the biquadratic interaction, and the out-of-plane Dzyaloshinsky–Moriya interaction defined in momentum space can give rise to a variety of double-Q and triple-Q vortex crystals. We further examine the role of easy-plane single-ion anisotropy in triple-Q vortex crystals and show that weakening the anisotropy drives topological transitions into skyrmion crystals with skyrmion numbers

\pm 1

and

\pm 2

. The influence of an external magnetic field is also analyzed, revealing a field-induced phase transition from vortex crystals to single-Q conical spirals. These findings highlight the crucial role of out-of-plane Dzyaloshinskii–Moriya interactions in stabilizing unconventional vortex crystals, which cannot be realized in systems with purely polar or chiral symmetries. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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7 pages, 2430 KB

Open AccessBrief Report

X-Ray Crystal Structure of the N-Terminal Domain of Staphylococcus aureus Cell-Cycle Protein GpsB

by Nathan I. Nicely, Thomas. M. Bartlett and Richard W. Baker

Crystals 2025, 15(10), 867; https://doi.org/10.3390/cryst15100867 - 30 Sep 2025

Viewed by 197

Abstract

GpsB is a conserved cell-cycle regulator in the Firmicute clade of Gram-positive bacteria that coordinates multiple aspects of envelope biogenesis. Recent studies demonstrate interactions between GpsB and the key division cytoskeleton FtsZ, suggesting that GpsB links cell division to various aspects of cell [...] Read more.

GpsB is a conserved cell-cycle regulator in the Firmicute clade of Gram-positive bacteria that coordinates multiple aspects of envelope biogenesis. Recent studies demonstrate interactions between GpsB and the key division cytoskeleton FtsZ, suggesting that GpsB links cell division to various aspects of cell envelope biogenesis in Staphylococcus aureus and potentially other Firmicutes. We determined a 1.7 Å resolution crystal structure of the N-terminal domain of Staphylococcus aureus GpsB, revealing an asymmetric dimer with a bent conformation. This conformation is nearly identical to one of two conformations reported by Sacco et al., confirming the unique conformation of S. aureus GpsB compared to other Gram-positive bacteria. This structural agreement provides strong validation of the S. aureus GpsB fold and supports its proposed role in organizing the cell division machinery. Full article

(This article belongs to the Section Biomolecular Crystals)

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13 pages, 1882 KB

Open AccessArticle

Crystallization of Four Troglitazone Isomers: Selectivity and Structural Considerations

by Shinji Matsuura, Koichi Igarashi, Masayuki Azuma and Hiroshi Ooshima

Crystals 2025, 15(10), 866; https://doi.org/10.3390/cryst15100866 - 30 Sep 2025

Viewed by 179

Abstract

The control of crystal form in chiral active pharmaceutical ingredients (APIs) is a critical challenge in pharmaceutical development, as differences in solid-state structure can significantly influence physical properties and manufacturing performance. Troglitazone, a molecule with two chiral centers, exists as four stereoisomers (RR, [...] Read more.

The control of crystal form in chiral active pharmaceutical ingredients (APIs) is a critical challenge in pharmaceutical development, as differences in solid-state structure can significantly influence physical properties and manufacturing performance. Troglitazone, a molecule with two chiral centers, exists as four stereoisomers (RR, SS, RS, SR) that crystallize as two enantiomeric pairs: RR/SS and RS/SR. This study aims to elucidate the relationship between solution-state molecular interactions and crystallization behavior of these diastereomeric pairs. Antisolvent crystallization experiments were conducted for both mixed solutions containing all four isomers and solutions of individual pairs. Crystallization kinetics were monitored by HPLC, and the resulting solids were characterized by PXRD, DSC, TG, and microscopic observation. Nucleation induction times were determined over a range of supersaturation levels. To probe intermolecular interactions in solution, NOESY and targeted NOE NMR experiments were performed, and the results were compared with crystallographic data. The RS/SR crystals(H-form) consistently exhibited shorter induction times and faster crystallization rates than the RR/SS crystals (L-form), even under conditions where RR/SS solutions were more supersaturated. In mixed solutions, H-form crystallized preferentially, with L-form either remaining in solution or being incorporated into H-form crystals as a solid solution. NOESY and NOE analyses revealed intermolecular proximities between protons that are distant in the molecular structure, indicating the presence of ordered aggregates in solution. These aggregates were more structurally compatible with the H-form than with the L-form crystal lattice, as supported by crystallographic distance analysis. The results demonstrate that differences in nucleation kinetics between troglitazone diastereomers are closely linked to solution-state molecular arrangements. Understanding these relationships provides a molecular-level basis for the rational design of selective crystallization processes for chiral APIs. Full article

(This article belongs to the Section Crystal Engineering)

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28 pages, 2204 KB

Open AccessArticle

2,2-Bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethanol: A Versatile Heteroscorpionate Ligand for Transition and Main Group Metal Complexes

by Uwe Böhme, Betty Günther and Anke Schwarzer

Crystals 2025, 15(10), 865; https://doi.org/10.3390/cryst15100865 - 30 Sep 2025

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Abstract

2,2-Bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethanol (HL) is a heteroscorpionate ligand capable of coordinating metal ions through two nitrogen atoms and one oxygen atom. We report a base free synthetic route to metal complexes of L and explore the resulting structural diversity. Notably, complex composition varies substantially depending [...] Read more.

2,2-Bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethanol (HL) is a heteroscorpionate ligand capable of coordinating metal ions through two nitrogen atoms and one oxygen atom. We report a base free synthetic route to metal complexes of L and explore the resulting structural diversity. Notably, complex composition varies substantially depending on the metal ion, including dinuclear molybdenum species and distinct coordination behavior with silicon and copper. The isolated compounds include the dinuclear, oxygen-bridged complexes (LMoO₂)₂O and (LMoO)(μ-O)₂, as well as the mononuclear complexes LTi(NMe₂)₃, LZrCl₃, LGeCl₃, LWO₂Cl, LCu(acetate)₂H, and LSiMe₂Cl. Single crystal X-ray diffraction reveals that the bulky complex structures generate cavities in the crystal lattice, frequently occupied by solvent molecules. The titanium, zirconium, molybdenum, tungsten, and germanium complexes exhibit octahedral coordination, while structural peculiarities are observed for copper and silicon. The copper(II) complex shows a distorted octahedral geometry with one elongated ligand bond; the silicon complex is pentacoordinated in the solid state. Additional characterization includes melting points, NMR, and IR spectroscopy. The developed synthetic strategy provides a straightforward and versatile route to heteroscorpionate metal complexes. Full article

(This article belongs to the Section Organic Crystalline Materials)

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