Previous Issue
Volume 15, August
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
5.0
2.4
Journals
Crystals
Volume 15
Issue 9
share announcement

Crystals, Volume 15, Issue 9 (September 2025) – 56 articles

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
18 pages, 3670 KB  
Article
Selective Crystallization of Trans-Nerolidol in β-Cyclodextrin: Crystal Structure and Molecular Dynamics Analysis
by Elias Christoforides, Athena Andreou, Polytimi Koskina and Kostas Bethanis
Crystals 2025, 15(9), 802; https://doi.org/10.3390/cryst15090802 - 11 Sep 2025
Abstract
Nerolidol (REL), a sesquiterpene with cis and trans isomers, exhibits diverse bioactive and sensory properties. In this study, we integrate single-crystal X-ray diffraction (SC-XRD), molecular docking, molecular dynamics (MD) simulations, and MM/GBSA binding free energy calculations to investigate its inclusion behavior in β-cyclodextrin [...] Read more.
Nerolidol (REL), a sesquiterpene with cis and trans isomers, exhibits diverse bioactive and sensory properties. In this study, we integrate single-crystal X-ray diffraction (SC-XRD), molecular docking, molecular dynamics (MD) simulations, and MM/GBSA binding free energy calculations to investigate its inclusion behavior in β-cyclodextrin (β-CD). Crystallization from a cis/trans mixture yielded a complex containing exclusively the trans isomer, forming a 2:1 host–guest assembly where a head-to-head β-CD dimer encapsulates one trans-REL molecule in an extended conformation. Computational models of cis-REL (bent c1 and extended c8 conformers) also stabilized within the β-CD cavity, with the extended conformer showing the most favorable dynamics. The computed binding affinities for all complexes differed by less than the estimated MM/GBSA uncertainty, indicating no statistically significant preference. Since cis/trans separation of nerolidol and related long-chain terpenoids is of considerable interest, our findings suggest that crystallization selectivity in β-CD inclusion complexes cannot be rationalized solely by binding affinity; instead, it likely arises from crystal packing forces and conformational preferences that govern the solid-state assembly. Full article
(This article belongs to the Section Macromolecular Crystals)
►▼ Show Figures

Figure 1

19 pages, 4277 KB  
Article
Comparative Finite Element Analysis of Fatigue Crack Growth in High-Performance Metallic Alloys: Influence of Material Parameters and Paris Law Constants
by Yahya Ali Fageehi and Abdulnaser M. Alshoaibi
Crystals 2025, 15(9), 801; https://doi.org/10.3390/cryst15090801 - 11 Sep 2025
Abstract
This study presents a comparative analysis of fatigue crack growth (FCG) in four high-performance crystalline metallic alloys: Inconel 718, Ti-6Al-4V, Aluminum 7075-T6, and ASTM A514 Steel. The Finite Element Method was utilized to simulate crack propagation and quantify the individual and synergistic effects [...] Read more.
This study presents a comparative analysis of fatigue crack growth (FCG) in four high-performance crystalline metallic alloys: Inconel 718, Ti-6Al-4V, Aluminum 7075-T6, and ASTM A514 Steel. The Finite Element Method was utilized to simulate crack propagation and quantify the individual and synergistic effects of key material properties, including Paris Law constants (C and m), yield strength, and modulus of elasticity, on FCG behavior. The analysis integrates simulation-driven parametric studies to quantify the impact on performance indicators (fatigue life cycles, equivalent stress intensity factors, safety factors, von Mises stress, and strain energy), and provides a quantitative analysis of secondary parameters. The results provide a robust, data-driven framework for material selection in aerospace, industrial, and structural applications where fatigue life is a paramount design consideration. Key findings reveal that Inconel 718 exhibits vastly superior fatigue life which is approximately 15 times greater than the next best-performing material, ASTM A514 Steel. Conversely, Ti-6Al-4V demonstrated the lowest fatigue resistance. Full article
(This article belongs to the Special Issue Fatigue and Fracture of Crystalline Metal Structures)
►▼ Show Figures

Figure 1

11 pages, 5875 KB  
Article
Preferential Adsorption of Single-Stranded DNA on Graphene Oxide with Hydroxyl and Epoxy Groups
by Huishu Ma, Xiaodan Huang, Shijun Wang, Mei Wu, Hanbing Wang, Guowei Shao, Liang Zhao and Xiaoling Lei
Crystals 2025, 15(9), 800; https://doi.org/10.3390/cryst15090800 - 10 Sep 2025
Abstract
The interaction between DNA and two-dimensional materials, such as graphene oxide (GO), has aroused significant research interest due to its potential applications, including biosensors, drug delivery, and gene therapy. However, the difference in interaction between DNA and oxygen functional groups on GO remains [...] Read more.
The interaction between DNA and two-dimensional materials, such as graphene oxide (GO), has aroused significant research interest due to its potential applications, including biosensors, drug delivery, and gene therapy. However, the difference in interaction between DNA and oxygen functional groups on GO remains unclear, and direct observation at the experimental level is still challenging. In this work, we investigated the adsorption process of a single-stranded DNA (ssDNA) onto GO exhibiting a series of oxidation degrees by molecular dynamics simulations. We found that the ssDNA preferentially binds to hydroxyl groups (-OH) over epoxy groups (-O-) on the GO surface. This preferential adsorption feature may be attributed to the stronger tendency of ssDNA to form hydrogen bonds (HBs) with hydroxyl groups compared to epoxy groups in aqueous solutions. Further analysis indicates that the affinity interaction between ssDNA and hydroxyl groups presumably increases the oxidation degree of GO, thus suggesting a better binding between ssDNA and GO. This work is not only expected to provide the underlying mechanism of ssDNA onto graphene-based interfaces but also offers a deeper understanding of the structures of DNA-two-dimensional complexes, which may potentially contribute to designing new molecular structures for bio-sensing-related nano-devices and nanostructures. Full article
(This article belongs to the Section Biomolecular Crystals)
►▼ Show Figures

Figure 1

16 pages, 2758 KB  
Article
Caysichite-(Y) from the Ploskaya Mountain (Kola Peninsula, Russia): Crystal-Structure Refinement and the Chemical Formula
by Sergey V. Krivovichev, Victor N. Yakovenchuk, Olga F. Goychuk and Yakov A. Pakhomovsky
Crystals 2025, 15(9), 799; https://doi.org/10.3390/cryst15090799 - 9 Sep 2025
Abstract
The crystal structure of caysichite-(Y) from the Ploskaya Mt (Kola Peninsula, Russia) has been refined to R1 = 0.051 for 4472 unique observed reflections. The mineral is orthorhombic, Ccm21, a = 13.2693(3), b = 13.9455(4), c = 9.7384(2) Å, [...] Read more.
The crystal structure of caysichite-(Y) from the Ploskaya Mt (Kola Peninsula, Russia) has been refined to R1 = 0.051 for 4472 unique observed reflections. The mineral is orthorhombic, Ccm21, a = 13.2693(3), b = 13.9455(4), c = 9.7384(2) Å, V = 1802.06(8) Å3, Z = 4. There are two M sites predominantly occupied by Y, but also including Ca and other rare earth elements (REEs). Both M sites are coordinated by eight O atoms to form distorted bicapped trigonal prisms. The crystal structure is based upon a three-dimensional framework formed by columns of MO8 polyhedra and (CO3) groups and double-crankshaft chains of SiO4 tetrahedra running parallel to the c-axis. The topology of linkage of MO8 polyhedra understood in terms of the M–M links shorter than 5 Å corresponds to the M network with the paracelsian (pcl) topology. The channels in the network are occupied by double-crankshaft Si chains and H2O groups. The new general chemical formula of a caysichite-(Y)-type mineral can be written as [Y2+2x−y′Ca2−3x−y″☐x+y′+y″][Si4O10](HCO3)3y′+2y″(CO3)3−3y′−2y″·(4−z)H2O, where z ~ 0.2; x ≤ 2/3; y′ ≤ 2/3; y″ ≤ 1; 3y′+2y″ ≤ 2. This general formula allows for several end-member formulas according to different x, y′ and y″ values: (Y2Ca2)[Si4O10](CO3)3·4H2O (x = y′ = y″ = z = 0), (Y2Ca☐)[Si4O10](HCO3)2(CO3)·4H2O (x = y′ = z = 0; y″ = 1), (Y10/3☐2/3)[Si4O10](CO3)3·4H2O (y′ = y″ = z = 0; x = 2/3), Ca2Y4/3☐2/3)[Si4O10](HCO3)2(CO3)·4H2O (x = y″ = z = 0; y′ = 2/3). The samples studied in this work have the compositions (REE2.05Ca1.87☐0.18)[Si4O10](HCO3)0.11(CO3)2.89·3.8H2O (x = 0.025, y′ = 0, y″ = 0.055) and (REE2.25Ca1.52☐0.23)[Si4O10](HCO3)0.21(CO3)2.79·3.8H2O (x = 0.125, y′ = 0, y″ = 0.115). The end-member formula most close to these compositions is (Y2Ca2)[Si4O10](CO3)3·4H2O, which is different from the formula (Ca,Yb,Er)4Y4(Si8O20)(CO3)6(OH)·7H2O currently adopted by the International Mineralogical Association but is generally identical to the formula (Y,Ca)4Si4O10(CO3)3·4H2O proposed in the original study of the mineral. In order to resolve the problem of the caysichite-(Y) formula, additional studies of materials from different localities (and, especially, one from the holotype locality) are needed. Full article
(This article belongs to the Special Issue Crystal Structure and Characterization of Minerals and Related Nanomaterials)
►▼ Show Figures

Figure 1

10 pages, 3902 KB  
Article
Negative Capacitance Effect at Interface Between Si Wafers with Undulating Surfaces
by Hikaru Yasunaga, Kota Yano, Yuki Tanioka, Sota Fujimoto, Shigeru Kanemitsu and Yong Sun
Crystals 2025, 15(9), 798; https://doi.org/10.3390/cryst15090798 - 9 Sep 2025
Abstract
The field emission current in a vacuum (IT=αE2/eβ/E, where α and β are constants) depends on the electric field strength E. In other words, the differential resistance [...] Read more.
The field emission current in a vacuum (IT=αE2/eβ/E, where α and β are constants) depends on the electric field strength E. In other words, the differential resistance (dIT/dV)−1 in a vacuum does not follow Ohm’s law. Therefore, the relationship governing the capacitance and current between two electrodes in a vacuum is an intriguing research topic. In this study, we constructed an interface structure in which contact areas and non-contact vacuum areas coexisted by adhering two Si wafers and measuring the capacitance characteristics of this structure. A volatile capacitance appeared at the interface, with the contact areas contributing to positive capacitance and the vacuum areas contributing to negative capacitance. The tunneling current passing through the interface played an important role in the formation of the negative capacitance. Full article
(This article belongs to the Section Crystal Engineering)
►▼ Show Figures

Figure 1

21 pages, 5533 KB  
Article
Integrated Chromogenic Analysis of Freshwater Pearls: Revealing the Internal Factors Driving Color Variation
by Baoyi Yang, Bo Xu, Yi Zhao, Chenxi Zhang, Siyi Zhao and Zheyi Zhao
Crystals 2025, 15(9), 797; https://doi.org/10.3390/cryst15090797 - 8 Sep 2025
Abstract
Pearl color serves as the paramount criterion for quality assessment and commercial valuation in the global pearl industry. Freshwater nucleated pearls, which constitute 95% of global production, exhibit striking chromatic diversity. This study deciphers the chromogenic mechanisms of freshwater nucleated cultured pearls in [...] Read more.
Pearl color serves as the paramount criterion for quality assessment and commercial valuation in the global pearl industry. Freshwater nucleated pearls, which constitute 95% of global production, exhibit striking chromatic diversity. This study deciphers the chromogenic mechanisms of freshwater nucleated cultured pearls in Hyriopsis cumingii from Zhuji, China, through integrated spectroscopic (UV-vis-NIR and Raman), colorimetric (CIELAB), and trace-element (LA-ICP-MS) analyses. We identify polyene compounds as the primary organic chromophores, with C=C bond counts determining core hue: purple (12 C=C bonds), pink (11 C=C bonds), and white/orange (10 C=C bonds). Color expression is further modulated by nacre microstructure; densely aligned aragonite tablets enhance optical interference in purple pearls, whereas irregular tablet arrangements in pink and orange pearls promote diffuse scattering. Crucially, trace elements (Mn, Fe, Cu, Zn) contribute synergistically via metalloporphyrin formation (e.g., Mn-porphyrin in purple variants) and aragonite lattice substitutions. These findings reveal that pearl coloration arises from the interplay of biological factors (organic matrix), physical structure (nacre architecture), and chemical composition (trace elements), providing insights for quality enhancement and sustainable aquaculture practices. Full article
(This article belongs to the Collection Topic Collection: Mineralogical Crystallography)
►▼ Show Figures

Figure 1

19 pages, 3739 KB  
Article
Theoretical Insights into the Molecular Interaction in Li-Ion Battery Electrolytes from the Perspective of the Dielectric Continuum Solvation Model
by Yumeng Zhao, Runmin Li, Xiaoxiao Li, Xinsheng Zhao, Yunsong Li and Yuxiao Lin
Crystals 2025, 15(9), 796; https://doi.org/10.3390/cryst15090796 - 8 Sep 2025
Abstract
Rational electrolyte design stands as a frontier in the research and development of Li-ion batteries. Nevertheless, detailed investigations about the influence of the dielectric continuum solvation model on molecular interactions are still limited. Herein, we systematically study the impacts of the dielectric constant [...] Read more.
Rational electrolyte design stands as a frontier in the research and development of Li-ion batteries. Nevertheless, detailed investigations about the influence of the dielectric continuum solvation model on molecular interactions are still limited. Herein, we systematically study the impacts of the dielectric constant (ε) on isolated molecules (i.e., ions and solvent molecules), isolated ion pairs, and solvation complexes via density functional theory calculations. The energy shift due to solvation cavity creation is the largest, and charged species always have larger energy shifts than neutral species. For charged species, the energy shifts gradually decrease with a decreasing proportion of Li ions and an increasing proportion of anions, while for neutral species, larger dipole moments lead to higher energy shifts. As predicted by the relative method, the energetic order of ion pairs and solvation complexes in vacuum can be dramatically changed in various dielectric continuums. Furthermore, electrochemical stability windows of charged species change dramatically with ε, while those of neutral species stay almost constant. By clarifying the impacts of dielectric continuum solvation on molecular interactions, we hope to set a benchmark for the molecular interaction calculation, which is critical for the rational design of electrolytes in Li-ion batteries. Full article
(This article belongs to the Special Issue New Insights into the Development of High-Specific-Energy Battery Materials)
►▼ Show Figures

Figure 1

17 pages, 5028 KB  
Article
Mechanical and Corrosion Properties of Ultrafine-Grained TC4-0.55Fe Alloy Processed by Equal-Channel Angular Pressing
by Yumeng Guo, Yu Lu, Miaoxia He, Yu Wang, Yuecheng Dong and Igor V. Alexandrov
Crystals 2025, 15(9), 795; https://doi.org/10.3390/cryst15090795 - 8 Sep 2025
Viewed by 38
Abstract
This study investigates the effects of multi-pass Equal-Channel Angular Pressing (ECAP) on the mechanical and corrosion properties of TC4-0.55Fe alloy through room-temperature tensile tests, electrochemical experiments, SEM, and EBSD characterization. The results demonstrate that, with increasing ECAP passes, the average grain size is [...] Read more.
This study investigates the effects of multi-pass Equal-Channel Angular Pressing (ECAP) on the mechanical and corrosion properties of TC4-0.55Fe alloy through room-temperature tensile tests, electrochemical experiments, SEM, and EBSD characterization. The results demonstrate that, with increasing ECAP passes, the average grain size is progressively refined from the initial 3.8 μm to 1.8 μm after four passes. After four passes, the yield strength and ultimate tensile strength increase from initial values of 906 MPa and 939 MPa to 995 MPa and 1022 MPa, respectively, while the elongation at fracture slightly decreases to 12.0%. Electrochemical corrosion results reveal that ECAP processing significantly enhances the corrosion resistance of the TC4-0.55Fe alloy. Specifically, the two-pass specimen exhibits nearly an order-of-magnitude reduction in both corrosion rate and self-corrosion current density compared to the initial state. The simultaneous improvement in strength and corrosion resistance is primarily attributed to the synergistic effects of grain refinement, increased dislocation density, and the evolution of basal texture. Full article
►▼ Show Figures

Figure 1

1 pages, 122 KB  
Correction
Correction: Alkentar et al. Development of Patient-Specific Lattice Structured Femoral Stems Based on Finite Element Analysis and Machine Learning. Crystals 2025, 15, 650
by Rashwan Alkentar, Sándor Manó, Dávid Huri and Tamás Mankovits
Crystals 2025, 15(9), 794; https://doi.org/10.3390/cryst15090794 - 8 Sep 2025
Viewed by 20
Abstract
Removal Affiliation [...] Full article
16 pages, 2660 KB  
Article
First-Principles Investigation of the Structural Stability and Physical Properties of Lead-Free Ge-Based Halide Perovskites
by Liang Wang, Longze Li, Jiayin Zhang, Shuying Zhong, Bo Xu, Musheng Wu and Chuying Ouyang
Crystals 2025, 15(9), 793; https://doi.org/10.3390/cryst15090793 - 5 Sep 2025
Viewed by 265
Abstract
Inorganic lead halide perovskite semiconductor materials exhibit great potential in the optoelectronic field due to their excellent optical and electrical properties. However, lead toxicity and limited material stability hinder their commercial applications. Consequently, the pursuit of non-toxic, stable alternatives is imperative for the [...] Read more.
Inorganic lead halide perovskite semiconductor materials exhibit great potential in the optoelectronic field due to their excellent optical and electrical properties. However, lead toxicity and limited material stability hinder their commercial applications. Consequently, the pursuit of non-toxic, stable alternatives is imperative for the sustainable development of halide-perovskite semiconductors. Non-toxic germanium-based halide perovskites, as promising candidates, have attracted considerable attention. Here, we present a systematic first-principles investigation of the structural, electronic, elastic, and optical properties of cost-effective germanium-based halide perovskites NaGeX3 (X = Cl, Br, I). Energy and phonon-spectrum calculations demonstrate that NaGeX3 with the R3c space group exhibits the highest structural stability, rather than the commonly assumed cubic phase. Hybrid functional calculations reveal that the band gaps of R3c NaGeX3 decrease monotonically with increasing halogen radius, that is, 4.75 eV (NaGeCl3) → 3.76 eV (NaGeBr3) → 2.69 eV (NaGeI3), accompanied by a reduction in carrier effective masses. Additionally, mechanically stable R3c NaGeX3 exhibits lower hardness and ductility than that of the cubic phase. Optical properties indicate that NaGeX3 materials have strong absorption coefficients (>106 cm−1) and low loss in the photon energy range of 9–11 eV, suggesting that such cost-effective germanium-based halide perovskites can be used in various optoelectronic devices in the ultraviolet region. Full article
(This article belongs to the Special Issue Emerging Perovskite Materials and Applications)
►▼ Show Figures

Figure 1

12 pages, 4654 KB  
Article
In Situ TEM Investigation of Dislocation-Mediated Deformation in Eutectic Fe36Ni18Mn33Al13 Alloy
by Fanling Meng, Jiaqi Zhu, Heyi Wang, Jiayi Li and Yang Lu
Crystals 2025, 15(9), 792; https://doi.org/10.3390/cryst15090792 - 5 Sep 2025
Viewed by 272
Abstract
Eutectic FeNiMnAl multi-principal element alloys exhibit exceptional strength–ductility synergy, yet their dynamic deformation mechanisms remain poorly characterized. This study employs in situ transmission electron microscopy to investigate dislocation-mediated plasticity in Fe36Ni18Mn33Al13—a lamellar FCC/B2 alloy with [...] Read more.
Eutectic FeNiMnAl multi-principal element alloys exhibit exceptional strength–ductility synergy, yet their dynamic deformation mechanisms remain poorly characterized. This study employs in situ transmission electron microscopy to investigate dislocation-mediated plasticity in Fe36Ni18Mn33Al13—a lamellar FCC/B2 alloy with balanced properties. Real-time observations under tensile loading (at a strain rate of 0.1 μm/s, with a resolution of ~2 nm) reveal coordinated dislocation planar glide, cross-slip at obstacles, and pile-up formation at phase boundaries. Planar slip bands dominate early deformation, while cross-slip facilitates barrier bypass and strain homogenization. The coarse microstructure of Fe36Ni18Mn33Al13 promotes extensive dislocation storage, reducing strength but enhancing ductility compared to finer FeNiMnAl variants. Full article
(This article belongs to the Special Issue Novel Nano-Materials: Material Characterization and Structural Analysis)
►▼ Show Figures

Figure 1

17 pages, 2954 KB  
Article
Reliability and Failure Probability Analysis of Al-Mg-Si/Al2O3–SiC Composites Cast Under Different Mold Conditions Using Classical and Bayesian Weibull Models
by Mohammed Y. Abdellah, Fadhel T. Alabdullah, Fadhel Alshqaqeeq and Mohamed K. Hassan
Crystals 2025, 15(9), 791; https://doi.org/10.3390/cryst15090791 - 4 Sep 2025
Viewed by 272
Abstract
This study analyzes the compressive behavior and reliability of Al-Mg-Si (6061) metal matrix composites reinforced with different weight fractions of Al2O3 and SiC ceramics and cast with graphite and steel molds. Compression tests were carried out according to ASTM E9 [...] Read more.
This study analyzes the compressive behavior and reliability of Al-Mg-Si (6061) metal matrix composites reinforced with different weight fractions of Al2O3 and SiC ceramics and cast with graphite and steel molds. Compression tests were carried out according to ASTM E9 with 0–8 wt.% reinforcement. The mold material significantly influenced the strength due to the cooling rate and interfacial adhesion. A two-parameter Weibull model assessed statistical reliability and extracted the shape (β) and scale (η) parameters using linear regression. Advanced models—lifelines (frequentist) and Bayesian models—were also applied. Graphite molds yielded composites with higher shape parameters (β = 6.27 for Al2O3; 5.49 for SiC) than steel molds (β = 4.66 for Al2O3; 4.79 for SiC). The scale values ranged from 490–523 MPa. The lifelines showed similar trends, with the graphite molds exhibiting higher consistency and scale (ρ = 7.45–9.36, λ = 479.71–517.49 MPa). Bayesian modeling using PyMC provided posterior distributions that better captured the uncertainty. Graphite mold samples had higher shape parameters (α = 6.98 for Al2O3; 8.46 for SiC) and scale values of 489.07–530.64 MPa. Bayesian models provided wider reliability limits, especially for SiC steel. Both methods confirmed the Weibull behavior. Lifelines proved to be computationally efficient, while Bayesian analysis provided deeper insight into reliability and variability. Full article
(This article belongs to the Special Issue Microstructural Characterization and Property Analysis of Alloys)
►▼ Show Figures

Figure 1

21 pages, 5921 KB  
Article
Crystal Growth and Dissolution of Hydroxyapatite: The Role of Ascorbic Acid
by Ioannis Kalantzis, Panagiota D. Natsi and Petros G. Koutsoukos
Crystals 2025, 15(9), 790; https://doi.org/10.3390/cryst15090790 - 4 Sep 2025
Viewed by 311
Abstract
Ascorbic Acid (AA), an important biomolecule present in relatively high concentrations in blood and other biological fluids, has been rarely investigated with reference to its effect on the biological mineralization–demineralization processes. To our knowledge, the present work is one of an extremely limited [...] Read more.
Ascorbic Acid (AA), an important biomolecule present in relatively high concentrations in blood and other biological fluids, has been rarely investigated with reference to its effect on the biological mineralization–demineralization processes. To our knowledge, the present work is one of an extremely limited few found in the literature in which the effect of the presence of AA in mineralizing or demineralizing electrolyte solutions is addressed in a quantitative way. We have used the constant saturation method for the accurate measurement of the rates of crystal growth of hydroxyapatite (HAP, Ca5(PO4)3OH), the model compound of the inorganic component of the hard tissues of higher mammals. It was found that both crystal growth and dissolution were accelerated significantly. The increase in crystal growth rates showed stronger dependence on the solution supersaturation (120% increase for the highest and 460% for the lowest) in the presence of 0.1 mM of AA, pH 7.40, 37 °C, 0.15 M NaCl. The dissolution rate increase was less dependent (average of ca. 300% increase). It was concluded from the detailed characterization of the solid that the acceleration effect was due to the uptake of AA on the HAP surface. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
►▼ Show Figures

Figure 1

16 pages, 3068 KB  
Article
Reconfigurable GeTe’s Planar RGB Resonator Filter–Absorber
by Israel Alves Oliveira, Vitaly F. Rodriguez-Esquerre and Igor L. Gomes de Souza
Crystals 2025, 15(9), 789; https://doi.org/10.3390/cryst15090789 - 3 Sep 2025
Viewed by 363
Abstract
This study presents a reconfigurable planar photonic device capable of dynamically switching between optical filter and absorber functionalities by exploiting the phase transition properties of GeTe, a chalcogenide phase-change material. The device adopts a Metal–Dielectric–PCM architecture composed of silver (Ag), silicon dioxide (SiO [...] Read more.
This study presents a reconfigurable planar photonic device capable of dynamically switching between optical filter and absorber functionalities by exploiting the phase transition properties of GeTe, a chalcogenide phase-change material. The device adopts a Metal–Dielectric–PCM architecture composed of silver (Ag), silicon dioxide (SiO2), and GeTe layers, each playing a distinct role: the silver layer governs the transmission and absorption efficiency, the SiO2 layer controls the resonance conditions, and the GeTe layer determines the device’s scattering behavior via its tunable optical losses. Numerical simulations revealed that the structure enables high RGB transmission in the amorphous state and broadband absorption in the crystalline state. By adjusting geometric parameters—especially the metallic thickness—the device exhibits finely tunable spectral responses under varying polarizations and incidence angles. These findings highlight the synergistic interplay between material functionality and layer configuration, positioning this platform as a compact and energy-efficient solution for applications in tunable photonics, optical sensing, and programmable metasurfaces. Full article
(This article belongs to the Section Materials for Energy Applications)
►▼ Show Figures

Figure 1

21 pages, 1047 KB  
Article
Decomposition of Elasticity Tensor on Material Constants and Mesostructures of Metal Plates
by Genbao Liu, Chukun Wang, Risheng Zhu, Tengfei Zhao, Zhiwen Lan and Mojia Huang
Crystals 2025, 15(9), 788; https://doi.org/10.3390/cryst15090788 - 31 Aug 2025
Viewed by 375
Abstract
Most metal plates are orthorhombic aggregates of cubic crystallites. First, we discuss the representations of the stress tensor, the strain tensor, the elasticity tensor, and the rotation tensor under the Kelvin notation. Then, we give the decomposition of determining the material constants and [...] Read more.
Most metal plates are orthorhombic aggregates of cubic crystallites. First, we discuss the representations of the stress tensor, the strain tensor, the elasticity tensor, and the rotation tensor under the Kelvin notation. Then, we give the decomposition of determining the material constants and the mesostructure tensors on the metal plate of cubic crystallites. Under the Voigt model and the Reuss model, we derive the volume average stiffness tensor and the volume average flexibility tensor’s inverse, respectively, of cubic crystallites based on the decomposition. The elasticity tensors of the Voigt model and the Reuss model are upper and lower bounds of the effective elasticity tensor, respectively. We make use of an FEM example to check the decomposition of the elasticity tensor on the material constants and the mesostructures. The results of our decomposition are consistent with the FEM simulation’s results. Full article
►▼ Show Figures

Figure 1

29 pages, 9939 KB  
Article
Theoretical Insights and Experimental Studies of the New Layered Tellurides EuRECuTe3 with RE = Nd, Sm, Tb and Dy
by Anna V. Ruseikina, Evgenii M. Roginskii, Maxim V. Grigoriev, Vladimir A. Chernyshev, Alexander A. Garmonov, Ralf J. C. Locke and Thomas Schleid
Crystals 2025, 15(9), 787; https://doi.org/10.3390/cryst15090787 - 31 Aug 2025
Viewed by 350
Abstract
Single crystals of the layered EuRECuTe3 series with RE = Nd, Sm, Tb and Dy are obtained for the first time, completing the series of studies on quaternary tellurides synthesized using the halide flux method. These compounds crystallize in the [...] Read more.
Single crystals of the layered EuRECuTe3 series with RE = Nd, Sm, Tb and Dy are obtained for the first time, completing the series of studies on quaternary tellurides synthesized using the halide flux method. These compounds crystallize in the orthorhombic space group Pnma (no. 62) with unit cell parameters ranging from a = 11.5634(7) Å, b = 4.3792(3) Å and c = 14.3781(9) Å for EuNdCuTe3 to a = 11.2695(7) Å, b = 4.3178(3) Å and c = 14.3304(9) Å for EuDyCuTe3. The influence of prismatic polyhedra [EuTe6+1]7− structural units on the stabilization of 3d framework composed by 2d layered fragments [RECuTe3]2−, which have a key role in the interlayer interaction, is established. A comparative analysis of structural and magnetic properties dependence on the rare-earth element radius ri(RE3+) in the EuRECuTe3 series (RE = Sc, Y, Nd–Lu) is carried out. The structural contraction, including decrease in degree of tetrahedral polyhedra distortion, bond lengths shortening and unit cell volume shrinking with increasing ri(RE3+), is established. It is shown that the structural alternation leads to transition from ferromagnetic to ferrimagnetic ordering. It was established that changes in the cationic sublattice have a more significant impact on structural transitions in the series of quaternary tellurides than changes in the anionic sublattice. The electronic structure and elastic and dynamic properties were estimated using ab initio calculations. The exfoliation energy for each compound is obtained by estimation of monolayer ground state energy as a result of structure relaxation. The symmetry and structural properties of monolayer EuRECuTe3 (RE = Nd, Sm, Tb, Dy) compound are established and the orthorhombic symmetry is obtained with layer group pm2_1b. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
13 pages, 4343 KB  
Article
Interfacial Engineering of Hydrophobic Montmorillonite for High-Energy-Capability Polypropylene Nanocomposite Dielectrics
by Shiheng Li, Guangsen Zheng, Chu Cao, Chaoqiong Zhu, Baojing Zhang, Ziming Cai and Peizhong Feng
Crystals 2025, 15(9), 786; https://doi.org/10.3390/cryst15090786 - 31 Aug 2025
Viewed by 402
Abstract
Polypropylene (PP) dielectric capacitors are crucial for electronics and electric power systems due to their high power density. However, their relatively low energy density limits their practical application in energy storage devices, presenting a long-standing challenge. Montmorillonite (MMT), a natural phyllosilicate mineral abundantly [...] Read more.
Polypropylene (PP) dielectric capacitors are crucial for electronics and electric power systems due to their high power density. However, their relatively low energy density limits their practical application in energy storage devices, presenting a long-standing challenge. Montmorillonite (MMT), a natural phyllosilicate mineral abundantly found on earth, features a two-dimensional nanosheet structure and excellent insulating properties. MMT nanosheets have shown promise in enhancing the breakdown strength and energy storage capability of PP dielectric, but compatibility issues with the PP matrix remain a challenge. In this study, we propose a novel surface modification strategy in which polystyrene (PS)-capped MMT (PCM) nanosheets are synthesized through a polymerization–dissolution process. The modified PCM nanosheets demonstrate improved compatibility and are well dispersed within the PP matrix. Optimal loading of the PCM nanosheets effectively dissipate charge energy and hinder the growth of electric trees in the PP matrix. As a result, the PP nanocomposite with 0.2 wt% PCM nanosheets exhibits an enhanced breakdown strength of 619 MV m−1 and a discharged energy density of 4.23 J cm−3, with an energy storage efficiency exceeding 90%. These findings provide a promising strategy for the development of high-energy-density dielectric capacitors in an economical manner. Full article
►▼ Show Figures

Figure 1

6 pages, 603 KB  
Article
Creation and Stability of Color Centers in BaF2 Single Crystals Irradiated with Swift 132Xe Ions
by Daurzhan Kenbayev, Michael V. Sorokin, Ayman S. El-Said, Alma Dauletbekova, Balzhan Saduova, Gulnara Aralbayeva, Abdirash Akilbekov, Evgeni Shablonin and Assyl-Dastan Bazarbek
Crystals 2025, 15(9), 785; https://doi.org/10.3390/cryst15090785 - 31 Aug 2025
Viewed by 464
Abstract
It was demonstrated that various defects can be induced in halide crystals by irradiation with swift heavy ions. Here, we irradiated barium fluoride (BaF2) single crystals with 220 MeV xenon ions at room temperature and performed stepwise thermal annealing up to [...] Read more.
It was demonstrated that various defects can be induced in halide crystals by irradiation with swift heavy ions. Here, we irradiated barium fluoride (BaF2) single crystals with 220 MeV xenon ions at room temperature and performed stepwise thermal annealing up to the temperature of 825 K to study the kinetics of ion-induced defects at different temperatures. Optical spectroscopy was utilized for the measurement of the wide range of absorption spectra from NIR to VUV. A sharp decrease in the F2 absorption peak was observed for the samples annealed in the temperature range of 400–450 K. This result can be explained by their recombination with anion interstitials during thermal decay of the complex hole centers. The mobile interstitials, those did not recombine with the F2 centers, increase the absorption peaks in the 9–10 eV region, which can be associated with interstitial aggregates. Full article
(This article belongs to the Section Crystal Engineering)
►▼ Show Figures

Figure 1

13 pages, 5650 KB  
Article
Coaxial Wire Feeding-Friction Stir Additive Manufacturing
by Mengmeng Liu, Rui Wang, Xiaohu Zhu, Ximing Cheng and Songmo Li
Crystals 2025, 15(9), 784; https://doi.org/10.3390/cryst15090784 - 31 Aug 2025
Viewed by 380
Abstract
At present, most studies in the field of Wire-Friction Stir Additive Manufacturing (W-FSAM) adopt the side wire feeding method. However, the side wire feeding method has problems in that the wire feeding tube occupies working space and the tool is prone to clogging. [...] Read more.
At present, most studies in the field of Wire-Friction Stir Additive Manufacturing (W-FSAM) adopt the side wire feeding method. However, the side wire feeding method has problems in that the wire feeding tube occupies working space and the tool is prone to clogging. To address this, this study proposes a Coaxial Wire Feeding-Friction Stir Additive Manufacturing (CWF-FSAM) method. The CWF-FSAM device adopts a structure where a fixed shaft is coaxially nested inside the stirring shaft, and the fixed shaft is machined with through-channels along the circumferential direction for wire feeding, which eliminates the limitation of the wire feeding tube. This study elaborates on the structure of the CWF-FSAM device, then uses 6061 aluminum alloy as the deposition material for additive manufacturing, and conducts characterization and analysis on the microstructure and mechanical properties of the deposited components. The results show that the interlayer bonding of the deposited components is dense without defects. The components exhibit uniform and fine equiaxed grains, with the average grain sizes of the top, middle, and bottom parts being 3.52 µm, 3.35 µm, and 4.07 µm, respectively. In terms of mechanical properties, the tensile strengths of the components along the building direction (BD) and longitudinal direction (LD) both reach 70% of that of the base material (BM) wire. The hardness ranges from 36 HV to 42 HV. In addition, closed-loop components were prepared by continuous counterclockwise deposition using the CWF-FSAM device. The tensile strengths of the overlapping area, straight section, and corner were 124.45 MPa, 125.88 MPa, and 126.95 MPa, respectively. The overall performance of the closed-loop components is uniform and stable, which indicates that the CWF-FSAM-deposited components have good mechanical property isotropy. Full article
(This article belongs to the Special Issue Advanced Welding and Additive Manufacturing)
►▼ Show Figures

Figure 1

17 pages, 2890 KB  
Article
Boosting the Photocatalytic Behavior of PbS/TiO2 Nanocomposites via the Pulsed Laser Deposition of PbS Nanoparticles onto TiO2 Nanotube Arrays Under Various Helium Background Pressures
by Ameni Rebhi, Karim Choubani, Anouar Hajjaji, Mohamed Ben Rabha, Mohammed A. Almeshaal, Brahim Bessais, Mounir Gaidi and My Ali El Khakani
Crystals 2025, 15(9), 783; https://doi.org/10.3390/cryst15090783 - 31 Aug 2025
Viewed by 416
Abstract
In this study, highly ordered titanium dioxide nanotubes (TiO2-NTs) have been synthesized using the electrochemical anodization procedure. Subsequently, the TiO2-NTs were successfully decorated with PbS nanoparticles (NPs) using the pulsed KrF-laser deposition (PLD) technique under vacuum and under different [...] Read more.
In this study, highly ordered titanium dioxide nanotubes (TiO2-NTs) have been synthesized using the electrochemical anodization procedure. Subsequently, the TiO2-NTs were successfully decorated with PbS nanoparticles (NPs) using the pulsed KrF-laser deposition (PLD) technique under vacuum and under different Helium background pressures (PHe) ranging from 50 to 400 mTorr. The prepared samples (PbS-NPs/TiO2-NTs) were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and UV–Vis and photoluminescence spectroscopies. XRD analyses confirmed that all TiO2-NTs crystallized in the anatase phase, while the PbS-NPs crystallized in the cfc lattice. The average crystallite size of the (200) crystallites was found to increase from 21 to 33 nm when the pressure of helium (PHe) was raised from vacuum to 200 mTorr and then dropped back to ~22 nm at PHe = 400 mTorr. Interestingly, the photoluminescence intensity of the PbS-NPs/TiO2-NTs samples was found to start diminishing for PHe ≥ 200 mTorr, indicating a lesser recombination rate of the photogenerated carriers, which also corresponded to a better photocatalytic degradation of the Amido Black (AB) dye. Indeed, the PbS-NPs/TiO2-NTs samples processed at PHe = 200 and 300 mTorr were found to exhibit the highest photocatalytic degradation efficiency towards AB with a kinetic constant 130% higher than that of bare TiO2-NTs. The PbS-NPs/TiO2-NTs photocatalyst samples processed under PHe = 200 or 300 mTorr were shown to remove 98% of AB within 180 min under UV light illumination. Full article
(This article belongs to the Special Issue Recent Advances in Photocatalysts Materials)
►▼ Show Figures

Figure 1

11 pages, 1745 KB  
Article
Spectroscopic Evidence for the α-FeOOH-to-ε-FeOOH Phase Transition: Insights from High-Pressure and High-Temperature Raman Spectroscopy
by Shanece S. Esdaille, Vadym Drozd, Andriy Durygin, Wenhao Li and Jiuhua Chen
Crystals 2025, 15(9), 782; https://doi.org/10.3390/cryst15090782 - 31 Aug 2025
Viewed by 363
Abstract
We conducted in situ Raman spectroscopy measurements on goethite (α-FeOOH) under simultaneous high-pressure and high-temperature conditions using an externally heated diamond anvil cell (EHDAC). Our study investigates spectral changes associated with the α-FeOOH-to-ε-FeOOH phase transition up to ~11 GPa and 563 K. The [...] Read more.
We conducted in situ Raman spectroscopy measurements on goethite (α-FeOOH) under simultaneous high-pressure and high-temperature conditions using an externally heated diamond anvil cell (EHDAC). Our study investigates spectral changes associated with the α-FeOOH-to-ε-FeOOH phase transition up to ~11 GPa and 563 K. The phase transition was identified based on high-temperature Raman spectra collected at 473 K, 523 K, and 563 K. A key indicator of the transition is the disappearance of a characteristic shoulder peak near 410 cm−1 which occurs near 4.7, 6.0, and 6.6 GPa for temperatures of 473 K, 523 K, and 563 K, respectively. From this, we estimate a linear phase boundary where the transition pressure increases with temperature at a rate of 2.3 ± 0.5 GPa per 100 K. Extrapolation to room temperature (300 K) yields a transition pressure of 0.3 ± 3.1 GPa. These findings extend existing high-pressure Raman data from ambient to elevated temperatures up to 563 K, improving our understanding of hydrogen-bearing phases relevant to Earth’s deep interior. Full article
►▼ Show Figures

Figure 1

14 pages, 3219 KB  
Article
Effects of Mn and Co Doping on the Electronic Structure and Optical Properties of Cu2ZnSnS4
by Xiufan Yang, Xinmao Qin, Wanjun Yan, Chunhong Zhang and Dianxi Zhang
Crystals 2025, 15(9), 781; https://doi.org/10.3390/cryst15090781 - 30 Aug 2025
Viewed by 410
Abstract
The electronic structures and optical properties of Mn-doped, Co-doped, and (Mn,Co)-co-doped Cu2ZnSnS4 were calculated and analyzed using the first-principles pseudopotential plane-wave approach. The results indicate that doping with Mn or Co increases the bond population and decreases the bond length [...] Read more.
The electronic structures and optical properties of Mn-doped, Co-doped, and (Mn,Co)-co-doped Cu2ZnSnS4 were calculated and analyzed using the first-principles pseudopotential plane-wave approach. The results indicate that doping with Mn or Co increases the bond population and decreases the bond length of the S-Mn and S-Co bonds, respectively, enhancing their covalent character. The undoped Cu2ZnSnS4 exhibits a bandgap of 0.16 eV, whereas doping with Mn or Co introduces impurity levels near the Fermi level, resulting in bandgap narrowing. Within the visible light spectrum, the static dielectric constant ε1(0) reaches its maximum value of 67.7 under co-doping conditions, and the absorption coefficient also attains its maximum value of 6.7 × 104 cm−1 under co-doping. Doping with Mn and Co induces a redshift (shift towards lower energy) in both the absorption peaks and dielectric function peaks, concomitantly increasing the probability of photon-induced electronic transitions. Conversely, doping shifts the reflectivity peaks towards higher energies (blue-shift), with the most pronounced blue-shift occurring under co-doping; the strongest reflectivity peaks remain below 43%. A prominent conductivity peak is observed at 1.7 eV. Doping shifts this peak position towards lower energies, with the maximum peak intensity reaching 1.6. These findings collectively suggest that Mn and Co doping effectively modulate key optical properties of Cu2ZnSnS4, such as its band gap and absorption coefficient, constituting an effective strategy for enhancing its optoelectronic transport characteristics. Full article
►▼ Show Figures

Figure 1

15 pages, 3287 KB  
Article
Functionalized Polyphenols: Understanding Polymorphism of 2-Chloro-3′,4′-Diacetoxy-Acetophenone
by Roxana Angela Tucaliuc, Sergiu Shova, Violeta Mangalagiu and Ionel I. Mangalagiu
Crystals 2025, 15(9), 780; https://doi.org/10.3390/cryst15090780 - 30 Aug 2025
Viewed by 402
Abstract
We report here an in-depth study concerning the synthesis, NMR, and X-ray structure determination of two new polymorphs of 2-chloro-3′,4′-diacetoxy-acetophenone. A new, ecologically friendly method of synthesis in the solid phase, as well as a suitable method for protecting hydroxyl functionality, is presented. [...] Read more.
We report here an in-depth study concerning the synthesis, NMR, and X-ray structure determination of two new polymorphs of 2-chloro-3′,4′-diacetoxy-acetophenone. A new, ecologically friendly method of synthesis in the solid phase, as well as a suitable method for protecting hydroxyl functionality, is presented. The 1H- and 13C-NMR spectra as well as the single crystal X-ray diffraction studies proved unambiguously the structure of the compounds: the two polymorphs of 2-chloro-3′,4′-diacetoxy-acetophenone and 2-chloro-3′-hydroxy-4′-acetoxy-acetophenone. The polymorph I crystalizes in the monoclinic P21/c space group, while polymorph II crystalizes in the Sohnke P212121 space group of the orthorhombic system, with no interstitial solvate molecules. Significant differences were observed in the supramolecular interactions in the crystal structure of the two polymorphs. Polymorph I is characterized as a parallel packing of weakly interacting supramolecular layers oriented in the 1 1 0 plane. The crystal structure of polymorph II is much more complex: each molecule is interconnected through 12 (twelve) hydrogen bonds with 9 (nine) adjacent symmetry-related molecules. The monoacetoxy derivative 2-chloro-3′-hydroxy-4′-acetoxy-acetophenone 3 crystallizes in the monoclinic P21/c space group, with one molecule in the asymmetric unit. Full article
(This article belongs to the Special Issue Polymorphism and Phase Transitions in Crystal Materials)
►▼ Show Figures

Figure 1

23 pages, 10645 KB  
Article
Analysis of Inclusions in the Entire Smelting Process of High-Grade Rare Earth Non-Oriented Silicon Steel
by Liqiang Xue, Xiangyu Li, Tao Wang, Qi Zhao, Haozheng Wang, Jia Wang, Wanming Lin, Xiaofeng Niu, Wangzhong Mu and Chao Chen
Crystals 2025, 15(9), 779; https://doi.org/10.3390/cryst15090779 - 30 Aug 2025
Viewed by 428
Abstract
Rare earth can modify inclusions in non-oriented silicon steel which is harmful to magnetic properties. This study focused on the 3.1% Si non-oriented silicon steel under industrial production conditions. Samples were taken during the stages before and after addition of rare earth ferrosilicon [...] Read more.
Rare earth can modify inclusions in non-oriented silicon steel which is harmful to magnetic properties. This study focused on the 3.1% Si non-oriented silicon steel under industrial production conditions. Samples were taken during the stages before and after addition of rare earth ferrosilicon alloy in Ruhrstahl-Heraeus (RH) unit, different pouring time in tundish, and continuous casting slab. This study systematically examined the morphology, composition, and size distribution of inclusions throughout the smelting process of non-oriented silicon steel by scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and thermodynamic analysis at liquid steel temperature and thermodynamic analysis of equilibrium solidification. The research results demonstrated that the rare earth treatment ultimately modifies the original Al2O3 inclusions in the non-oriented silicon steel into REAlO3 and RE2O2S inclusions, while also aggregating AlN inclusions to form composite inclusions. After rare earth modification, the average size of the inclusions decreases. In the RH treatment process, the inclusions before the addition of rare earth ferrosilicon alloy are mainly AlN and Al2O3. After the addition of rare earth ferrosilicon alloy, the inclusions are mainly RES and REAlO3. In the tundish and continuous casting, the rare earth content decreased, and the rare earth inclusions transform into RE2O2S and REAlO3. For the size of inclusions, after adding rare earth ferrosilicon alloy, the average size of inclusions rapidly decreased from 16.15 μm to 2.65 μm and reach its minimum size 2.16 μm at the end of RH treatment. When the molten steel entered the tundish, the average size of inclusions increased slightly and gradually decreased with the progress of pouring. The average size of inclusions in the slab is 5.79 μm. Phase stability diagram calculation indicates the most stable rare earth inclusion is Ce2O2S in molten steel. Thermodynamic calculations indicated that Al2O3, Ce2O2S, Ce2S3, AlN, and MnS precipitate sequentially during the equilibrium solidification process of molten steel. Full article
(This article belongs to the Special Issue Crystallization of High Performance Metallic Materials (2nd Edition))
►▼ Show Figures

Figure 1

13 pages, 2992 KB  
Article
Effect of Magnetic Stirring on the Microstructure of Eutectic Al-Si Alloys
by Éva Kócsák, András Roósz, Arnold Rónaföldi and Zsolt Veres
Crystals 2025, 15(9), 778; https://doi.org/10.3390/cryst15090778 - 30 Aug 2025
Viewed by 321
Abstract
This study focuses on the detailed investigation of the eutectic Aluminium Silicon (Al-12.6 wt% Si) alloy, which was solidified without and with a 10 mT induction rotating magnetic field (RMF). The experiments were conducted as part of the MICAST Hungary project, as the [...] Read more.
This study focuses on the detailed investigation of the eutectic Aluminium Silicon (Al-12.6 wt% Si) alloy, which was solidified without and with a 10 mT induction rotating magnetic field (RMF). The experiments were conducted as part of the MICAST Hungary project, as the mirror experiments were solidified in the Solidification and Quenching Furnace (SQF) at the International Space Station (ISS). The mirror samples were solidified using solidification parameters similar to the ISS experiments. This study examined the meso-structure of the samples and the eutectic microstructure in both stirred (RMF-applied) and non-stirred (RMF-free) samples. Special attention was given to the influence of magnetic stirring on key microstructural features, such as the eutectic lamellae distance, the length of the lamellae, and the spatial orientation of the lamellae were investigated. Measuring and analysing these parameters gives us an overall picture of the microstructure of the eutectics. The 10 mT low-intensity RMF used in the experiment has a demonstrable effect on the formation of the eutectic structure; short aluminium dendrites concentrate at both edges of the stirred sample, and their proportion decreases as the sample approaches its end. In contrast, in the non-stirred sample, long, elongated Al dendrites solidify parallel to the direction of heat removal, and their proportion and size continuously increase as the sample progresses. Furthermore, a possible relationship was found between the decrease in the eutectic lamella length and the lamellae’s average distance. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
►▼ Show Figures

Figure 1

17 pages, 4386 KB  
Article
A Numerical Analysis of the Fluid Flow in a Slab Mold Considering a SEN with Real Clogging and with Symmetrical Reductions
by Ariana López, Enif Gutiérrez, Saul Garcia-Hernandez, Rodolfo Morales-Dávila and Jose de Jesus Barreto
Crystals 2025, 15(9), 777; https://doi.org/10.3390/cryst15090777 - 30 Aug 2025
Viewed by 403
Abstract
Nozzle blockage has been a critical issue for productivity and product quality since the introduction of continuous casting. Despite numerous studies on the subject, the problem persists, affecting steel production. This detrimental phenomenon causes changes in the internal nozzle geometry and severe wall [...] Read more.
Nozzle blockage has been a critical issue for productivity and product quality since the introduction of continuous casting. Despite numerous studies on the subject, the problem persists, affecting steel production. This detrimental phenomenon causes changes in the internal nozzle geometry and severe wall irregularities that are neither symmetrical nor uniform. A common approach to studying the complex internal shape of clogged nozzles is considering nozzles with symmetrical transversal area reductions. Therefore, this study aims to quantitatively evaluate the effects of using realistic submerged entry nozzle (SEN) clogging geometries on the fluid dynamic behavior of molten steel inside the SEN and the mold and is compared to simplified symmetric reductions. A three-dimensional mathematical simulation based on the Navier–Stokes equations, the standard k − ε turbulence model, and the Volume of Fluid (VOF) method was used. The main findings indicate that symmetric reductions can only provide a qualitative prediction of the results, such as increased velocity and asymmetries at the meniscus bath level, but with errors that can reach up to 25%. Symmetric reductions fail to accurately capture the fluid dynamics inside the nozzle and the mold and should therefore be used with caution in studies that require precise flow characterization near the nozzle walls. Full article
►▼ Show Figures

Figure 1

17 pages, 6165 KB  
Article
The Resistance of X-Shaped Re-Entrant Auxetic Sandwich Beams to Localized Impulsive Loading
by Wei Zhang, Tongtong Qi, Huiling Wang, Xiang Chen, Xiang Li and Junhua Shao
Crystals 2025, 15(9), 776; https://doi.org/10.3390/cryst15090776 - 30 Aug 2025
Viewed by 401
Abstract
This study introduces an improved X-shaped re-entrant auxetic structure designed to enhance mechanical performance by incorporating diamond-shaped elements into the re-entrant hexagonal configuration. Using a validated numerical model, the resistance of sandwich beams with the proposed core under localized impulsive loading is explored. [...] Read more.
This study introduces an improved X-shaped re-entrant auxetic structure designed to enhance mechanical performance by incorporating diamond-shaped elements into the re-entrant hexagonal configuration. Using a validated numerical model, the resistance of sandwich beams with the proposed core under localized impulsive loading is explored. The results reveal that local compression and global shear deformation dominate the response. The study further examines the effects of cell arrangement, geometric parameter, inclined gradient distribution, and cell construction on structural behavior. The X-direction arrangement of cells significantly enhances deformation control, improving deflection by dissipating impact energy. Increasing the angle α enhances mechanical properties and reduces residual deflection. Various inclined gradient distribution designs notably affect performance: positive gradients improve energy absorption, while negative gradients alter deformation mode. Under the same conditions, the proposed sandwich beam outperforms the conventional re-entrant hexagonal sandwich beam in terms of impact resistance. This research offers valuable insights for the design of explosion-resistant metamaterial sandwich structures. Full article
(This article belongs to the Special Issue Mechanical Properties and Structure of Metal Materials)
►▼ Show Figures

Figure 1

12 pages, 4800 KB  
Article
Chromogenic Mechanism and Chromaticity Study of Brazilian Aquamarine
by Zheng Zhang, Endong Zu, Xiaohu He, Zixuan Wang, Die Wang, Yicong Sun, Yigeng Wang and Siqi Yang
Crystals 2025, 15(9), 775; https://doi.org/10.3390/cryst15090775 - 29 Aug 2025
Viewed by 290
Abstract
Aquamarine, a popular variety of blue beryl, faces challenges in market valuation due to its reliance on subjective color assessment. This study investigates the coloration mechanism and establish a quantitative framework for assessing its color based on spectral and chromaticity analysis. We utilized [...] Read more.
Aquamarine, a popular variety of blue beryl, faces challenges in market valuation due to its reliance on subjective color assessment. This study investigates the coloration mechanism and establish a quantitative framework for assessing its color based on spectral and chromaticity analysis. We utilized electron probe microanalysis, ultraviolet-visible-near-infrared spectroscopy, laser Raman spectroscopy, and fiber optic spectroscopy to examine Brazilian aquamarine samples with varying blue intensities. The results indicate that the samples have high alkali metal (Na, K) content and low V/Cr content, consistent with the characteristics of high-alkali beryl. Ultraviolet spectroscopy reveals that the Fe3+-Fe2+ interaction (absorption at 620 nm) is the primary cause of blue coloration, while in deep blue samples, absorption at 956 nm decreases. Raman shifts (317 cm−1, 392 cm−1 Al-O bonds) correlate with TFeO content and chromaticity b value higher TFeO content corresponds to smaller Al–O peak shifts, and larger shifts are associated with higher b values (yellow hue). Specifically, increasing TFeO content leads to a shift of the Al-O Raman peak towards higher wavenumbers, and the magnitude of this shift is negatively correlated with the TFeO level. Based on hue angle (H) and saturation (S), we propose a classification method: “Light Blue” (H: 140–170, S ≤ 15), “Sky Blue” (H: 170–200, 15 < S ≤ 25), “Ocean Blue” (H: 200–230, 25 < S ≤ 35), and “Deep Blue” (H > 230, S > 35). This system provides a scientific basis for the quality assessment and market valuation of aquamarine. Full article
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)
►▼ Show Figures

Figure 1

11 pages, 1787 KB  
Article
Multi-Step Spin-Coating with In Situ Crystallization for Growing 2D/3D Perovskite Films
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, Longlong Zhang, Tengteng Li, Cheng Lei and Ting Liang
Crystals 2025, 15(9), 774; https://doi.org/10.3390/cryst15090774 - 29 Aug 2025
Viewed by 337
Abstract
Developing perovskite solar cells (PSCs) with both high performance and long-term stability remains a critical challenge and research focus in the field of photovoltaic devices. Herein, we report a multi-step spin-coating strategy for high-efficiency 2D/3D perovskite heterojunction solar cells by sequentially depositing low-concentration [...] Read more.
Developing perovskite solar cells (PSCs) with both high performance and long-term stability remains a critical challenge and research focus in the field of photovoltaic devices. Herein, we report a multi-step spin-coating strategy for high-efficiency 2D/3D perovskite heterojunction solar cells by sequentially depositing low-concentration 3-pyridine methylamine iodine solutions onto 3D perovskite films. This approach enables controlled Ostwald ripening and forms graded 2D/3D heterointerfaces rather than insulating capping layers, yielding a champion device with a PCE of 22.7%, significantly outperforming conventional 2D/3D planar counterparts. The optimized structure exhibits enhanced carrier extraction, suppressed recombination, and exceptional humidity stability; the hydrophobic structure further enabled >85% initial efficiency retention after 800 h at 45% relative humidity (RH) for target devices. This study establishes a novel research paradigm for developing high-performance and stable 2D/3D perovskite solar cells through gradient dimensionality engineering. Full article
(This article belongs to the Section Materials for Energy Applications)
►▼ Show Figures

Figure 1

18 pages, 10585 KB  
Article
Optic Axis Rotation and Bertin Surface Deformation in Lead Tungstate (PWO) and Other Tetragonal Crystals by Stress and Misalignment of Crystallographic Cells: A Theoretical Study
by Luigi Montalto, Daniele Rinaldi and Fabrizio Davì
Crystals 2025, 15(9), 773; https://doi.org/10.3390/cryst15090773 - 29 Aug 2025
Viewed by 269
Abstract
For tetragonal lead tungstate (PWO) and other tetragonal crystals, we study modifications of the Bertin surfaces induced by either the distortion of crystallographic cells, the applied plane stress, or cell misalignment with respect to the specimen faces. In both cases, the distortions of [...] Read more.
For tetragonal lead tungstate (PWO) and other tetragonal crystals, we study modifications of the Bertin surfaces induced by either the distortion of crystallographic cells, the applied plane stress, or cell misalignment with respect to the specimen faces. In both cases, the distortions of the Bertin surfaces result in the reshaping of the interference pattern observed by conoscopy. We provide, for different observation directions of the crystals, analytical relations that allow for the evaluation of the optic plane and the optical indicatrix rotation with or without stress. By the means of these relations, interference image reshaping allows us to detect, provided that some conditions hold, the crystallographic axes’ rotation. This work is a theoretical study aiming to evaluate the optic axes and crystallographic cell orientation by means of conoscopic observations. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-56
Previous Issue
Back to TopTop