Crystals

11 pages, 11226 KiB

Open AccessEditor’s ChoiceArticle

Transformation Mechanism of Undercooled Austenite and Deformation Behavior of a 1.2 GPa High-Strength Medium Mn Steel

by Ying Dong, Jiachen Xu, Lingming Meng, Qinghao Miao, Haobo Cui, Jiaxin Chen, Yu Du, Tao Liu, Qingdong Feng and Chengjun Zhu

Crystals 2025, 15(5), 487; https://doi.org/10.3390/cryst15050487 - 21 May 2025

Viewed by 365

Abstract

In this study, the phase transformation mechanism during the decomposition of undercooled austenite and its effect on the deformation behavior of a high-strength medium Mn steel were studied. The results indicate that the austenite formation during heating (α → γ) is a relatively [...] Read more.

In this study, the phase transformation mechanism during the decomposition of undercooled austenite and its effect on the deformation behavior of a high-strength medium Mn steel were studied. The results indicate that the austenite formation during heating (α → γ) is a relatively fast reaction. However, the transformation of undercooled prior austenite above the martensite start (M_s) temperature (γ → α) is difficult due to its high thermal stability. Only martensite transformation occurred during the final air-cooling stage following a 120-h isothermal treatment at 360 °C (slightly above M_s). The growth of martensite laths was limited by the boundaries of prior austenite grains and martensite packets. High-strength tensile properties were achieved, with a yield strength of 955 MPa, ultimate tensile strength of 1228 MPa, and total elongation of 11.6%. These properties result from the synergistic hardening effects of grain refinement, high-density lattice distortion, and an increased boundary length per unit area. The composition design with medium Mn content increased the processing window for high-strength martensite transformation, providing a theoretical basis for an energy-saving approach that depends on the decomposition transformation of undercooled austenite. Full article

(This article belongs to the Special Issue Advances in High Performance Metal Materials: Preparation, Properties, and Applications)

► Show Figures

Figure 1

13 pages, 3899 KiB

Open AccessEditor’s ChoiceArticle

Growth and Characterization of High Doping Concentration (2.1 at%) Ytterbium (Yb) Doped Lithium Niobate (LiNbO₃) Crystal: An Electrically Tunable Lasing Medium

by Kaicheng Wu, Mohammad Ahsanul Kabir, Kai-ting Chou and Shizhuo Yin

Crystals 2025, 15(5), 486; https://doi.org/10.3390/cryst15050486 - 21 May 2025

Viewed by 386

Abstract

In this paper, we report on the growth and characterization of high doping concentration (2.1 at%) ytterbium (Yb) doped lithium niobate (Yb:LiNbO₃) crystal. By using a slightly modified Czochralski method, we have successfully grown a usable size (2 mm × 2 [...] Read more.

In this paper, we report on the growth and characterization of high doping concentration (2.1 at%) ytterbium (Yb) doped lithium niobate (Yb:LiNbO₃) crystal. By using a slightly modified Czochralski method, we have successfully grown a usable size (2 mm × 2 mm × 30 mm) Yb:LiNbO₃ single crystal. We also conducted the energy-dispersive X-ray spectroscopy (EDS) and the X-ray diffraction (XRD) analyses, which experimentally confirm that the grown crystal is a Yb:LiNbO₃ single crystal. We also measured the absorption and emission spectra of the grown crystal. It was found out that there is a near-flat broad emission within a spectral range of 1004–1030 nm when excited at 980 nm for this high doping concentration Yb:LiNbO₃ crystal. Such a near-flat broad emission can be very useful for realizing high slope efficiency ultrafast (femtosecond) lasing in the Yb:LiNbO₃ crystal due to the low quantum defect of the Yb:LiNbO₃ crystal. We also investigated the electro-optic effect of the Yb:LiNbO₃. The experimental result confirms that the electro-optic (EO) effect of a highly doped (2.1 at%) lithium niobate crystal is close to the EO value of the pure lithium niobate. Thus, the highly doped Yb:LiNbO₃ crystal can still be an effective electrically tunable lasing medium. It can enable electrically tunable, high slope efficiency femtosecond lasing due to the combined features, including (1) a near flat broad emission spectrum at the spectral range of 1004–1030 nm, (2) a non-compromised electro-optic effect at high doping concentration Yb:LiNbO₃ crystal, and (3) a low quantum defect. Full article

(This article belongs to the Special Issue Rare Earths-Doped Materials (3rd Edition))

► Show Figures

Figure 1

14 pages, 5702 KiB

Open AccessEditor’s ChoiceArticle

Co_0.85Bi_0.15Fe_1.9X_0.1O₄ (X = Ce⁴⁺, Sm³⁺, Ho³⁺, and Er³⁺) Nanoparticles with Selective Anticancer Activity: A Structural and Morphological Approach

by Liza Saher, Adel Benali, Saoussen Haddad, Essebti Dhahri, Manuel P. F. Graça, Benilde F. O. Costa, Luisa A. Helguero and Artur M. S. Silva

Crystals 2025, 15(5), 482; https://doi.org/10.3390/cryst15050482 - 20 May 2025

Viewed by 321

Abstract

In this work, we synthesized the Co_0.85Bi_0.15Fe_1.9X_0.1O₄ (X = Ce³⁺, Sm³⁺, Ho³⁺, and Er³⁺) nanoparticles via the auto-combustion method. The cell viability against two breast cancer [...] Read more.

In this work, we synthesized the Co_0.85Bi_0.15Fe_1.9X_0.1O₄ (X = Ce³⁺, Sm³⁺, Ho³⁺, and Er³⁺) nanoparticles via the auto-combustion method. The cell viability against two breast cancer cells (MDA-MB-231 and T-47D cells) and the PC3 prostate cancer cells were carefully analyzed and correlated with the structural parameters and particle size values as well as the chemical composition. The produced compounds’ morphological and structural characteristics were performed using scanning transmission microscopy (TEM) and X-ray Diffraction (XRD). For all compounds, the analyses of the XRD experimental data revealed a structurally reversed cubic spinel with space group Fd-3m. All of the compounds had crystallites smaller than 45 nm which concorded well with the particle size values deduced from TEM images. Co_0.85Bi_0.15Fe_1.9Ho_0.1O₄ nanoparticles induced a high mortality of breast and prostate cancer cells (MDA-MB-231, T-47D, and PC3) while the Co_0.85Bi_0.15Fe_1.9Sm_0.1O₄ compound (higher particle size) reduced almost 35% of MDA-MB-231 cancer cells. With very low cytotoxicity against normal human cells, the Co_0.85Bi_0.15Fe_1.9Ho_0.1O₄ nanoparticles play a significant role in the elimination of cancer cells. Full article

(This article belongs to the Special Issue Feature Papers on “Hybrid and Composite Crystalline Materials” 2025)

► Show Figures

Figure 1

10 pages, 2233 KiB

Open AccessEditor’s ChoiceArticle

Determination of the ²⁰⁷Pb Chemical Shift Tensor in Crocoite, PbCrO₄, Using Single-Crystal NMR Spectroscopy

by Sebastian Kläger, Otto E. O. Zeman and Thomas Bräuniger

Crystals 2025, 15(5), 480; https://doi.org/10.3390/cryst15050480 - 19 May 2025

Viewed by 277

Abstract

The full chemical shift tensor of ²⁰⁷Pb (spin

I = 1 / 2

) in the natural mineral crocoite, PbCrO₄, has been determined using single-crystal NMR spectroscopy at room temperature. The eigenvalues of the tensor in its principal axes system [...] Read more.

The full chemical shift tensor of ²⁰⁷Pb (spin

I = 1 / 2

) in the natural mineral crocoite, PbCrO₄, has been determined using single-crystal NMR spectroscopy at room temperature. The eigenvalues of the tensor in its principal axes system are

δ_{11} = - 2720 \pm 2

ppm,

δ_{22} = - 2319 \pm 4

ppm, and

δ_{33} = - 1830 \pm 5

ppm, resulting in an isotropic chemical shift of

δ_{iso} = - 2289 \pm 2

ppm. Additionally, these values were verified using a Herzfeld–Berger analysis of a polycrystalline sample under magic-angle spinning (MAS) conditions. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

► Show Figures

Figure 1

16 pages, 5110 KiB

Open AccessEditor’s ChoiceArticle

Effects of Nitrogen Partial Pressure on the Microstructure and Mechanical Properties of High-Entropy Ti(C,N)-Based Gradient Cermets

by Yunhao Zhang, Houan Zhang, Dongxu Qiao, Xin Tao, Peng Xia and Siyong Gu

Crystals 2025, 15(5), 479; https://doi.org/10.3390/cryst15050479 - 19 May 2025

Viewed by 296

Abstract

Titanium carbonitride (Ti(C,N))-based ceramics are widely utilized in mechanical machining, aerospace, and electronics, particularly in cutting tools and wear-resistant components. Two single-phase solid solution powders, non-high-entropy (Ti_0.83,W_0.07,Mo_0.04,Nb_0.03,Ta_0.04)(C_0.7,N_0.3) and high-entropy [...] Read more.

Titanium carbonitride (Ti(C,N))-based ceramics are widely utilized in mechanical machining, aerospace, and electronics, particularly in cutting tools and wear-resistant components. Two single-phase solid solution powders, non-high-entropy (Ti_0.83,W_0.07,Mo_0.04,Nb_0.03,Ta_0.04)(C_0.7,N_0.3) and high-entropy (Ti_0.6,W_0.1,Mo_0.1,Nb_0.1,Ta_0.1)(C_0.78,N_0.22), were synthesized via the carbothermal reduction–nitridation (CRN) method. Gradient-structured non-high-entropy (C-TiCN) and high-entropy (HE-TiCN) cermets were fabricated at 1450 °C by tailoring the nitrogen partial pressure in the range of 1–8 kPa. The effect of nitrogen partial pressure on the microstructure and mechanical properties of both materials was thoroughly analyzed. Both materials exhibited a three-layer gradient structure comprising a hard-phase-enriched surface layer, a binder-rich subsurface layer, and a chemically uniform core. Optimal performance was achieved at 4 kPa nitrogen partial pressure, at which both HE-TiCN and C-TiCN exhibited a desirable combination of surface hardness and fracture toughness. Compared with C-TiCN, HE-TiCN showed improvements in surface hardness and fracture toughness at subsurface and core regions (40 µm from the surface) by 4.9%, 11.2%, and 12.0%, respectively. The enhanced surface hardness of HE-TiCN is attributed to the significant lattice distortion and the synergistic effects associated with its high-entropy configuration. The improved toughness of the binder-rich layer is primarily ascribed to mechanisms such as crack deflection, crack branching, and the formation of tear ridges. These findings offer a promising strategy for developing gradient Ti(C,N)-based cermets with enhanced mechanical performance. Full article

(This article belongs to the Special Issue Structure and Properties of Ceramic Materials)

► Show Figures

Figure 1

28 pages, 7859 KiB

Open AccessEditor’s ChoiceArticle

Tailoring the Luminescence Properties of Strontium Aluminate Phosphors for Unique Smartphone Detectable Optical Tags

by Virginija Vitola, Milena Dile, Katrina Krizmane, Ernests Einbergs, Tinko Eftimov, Kristian Nikolov and Samia Fouzar

Crystals 2025, 15(5), 474; https://doi.org/10.3390/cryst15050474 - 17 May 2025

Viewed by 454

Abstract

In this work, a precursor-driven tailoring of strontium aluminate phosphors doped with Eu²⁺ and Dy³⁺ to generate unique, batch-specific luminescent signatures suitable for smartphone-detectable anti-counterfeiting tags was developed. A microwave-assisted hydrothermal synthesis approach was employed to explore the impact of a [...] Read more.

In this work, a precursor-driven tailoring of strontium aluminate phosphors doped with Eu²⁺ and Dy³⁺ to generate unique, batch-specific luminescent signatures suitable for smartphone-detectable anti-counterfeiting tags was developed. A microwave-assisted hydrothermal synthesis approach was employed to explore the impact of a wide range of alkaline hydroxide and carbonate precursors on the structure of strontium aluminate. The resulting materials exhibited distinct differences in crystalline phase composition, morphology, and trap depth distribution. A smartphone-based detection system was developed, enabling rapid identification of spectral fingerprints. This study demonstrates a viable strategy for embedding unique luminescent identifiers, offering a scalable solution for robust, low-cost anti-counterfeiting applications in both the spectral and the time domain. Full article

(This article belongs to the Section Polycrystalline Ceramics)

► Show Figures

Figure 1

15 pages, 6028 KiB

Open AccessEditor’s ChoiceArticle

Crystalline Li-Ta-Oxychlorides with Lithium Superionic Conduction

by Hao-Tian Bao, Bo-Qun Cao and Gang-Qin Shao

Crystals 2025, 15(5), 475; https://doi.org/10.3390/cryst15050475 - 17 May 2025

Viewed by 494

Abstract

Nowadays, some amorphous and microcrystalline solid-state electrolytes (SSEs) with dual anions have attained high ionic conductivity and good compatibility with electrodes in all-solid-state lithium-ion batteries (ASSLIBs). In this work, crystalline SSEs of series A (Li_1+xTaO_1+xCl_4−x [...] Read more.

Nowadays, some amorphous and microcrystalline solid-state electrolytes (SSEs) with dual anions have attained high ionic conductivity and good compatibility with electrodes in all-solid-state lithium-ion batteries (ASSLIBs). In this work, crystalline SSEs of series A (Li_1+xTaO_1+xCl_4−x, −0.70 ≤ x ≤ 0.50) and B (LiTaO_2+yCl_2−2y, −1.22 ≤ y ≤ 0), having great application potential well over ambient temperatures, were prepared at 260–460 °C for 2–10 h using Li₂O, TaCl₅, and LiTaO₃ as the raw materials. The three-phase coexisting samples attained high σ values ranging from 5.20 to 7.35 mS cm⁻¹, which are among the reported high values of amorphous co-essential SSEs and other alloplasmatic crystalline ones. It is attributed to the synergistic effect of the polyanion trans-[O₂Cl₄] and cis-[O₄Cl₂] octahedra framework. Full article

(This article belongs to the Special Issue Synthesis, Structure and Application of Metal Halides)

► Show Figures

Figure 1

24 pages, 100135 KiB

Open AccessEditor’s ChoiceArticle

The Influence of Annealing Temperature on the Microstructure and Performance of Cold-Rolled High-Conductivity and High-Strength Steel

by Shuhai Ge, Xiaolong Zhao, Weilian Zhou, Xueming Xu, Xingchang Tang, Junqiang Ren, Jiahe Zhang and Yaoxian Yi

Crystals 2025, 15(5), 469; https://doi.org/10.3390/cryst15050469 - 16 May 2025

Viewed by 552

Abstract

Low-carbon micro-alloyed steel has become a wire material with great potential for further development due to its excellent comprehensive performance; however, there is still a lack of insight into the evolution of its electrical conductivity during annealing treatment after undergoing deformation. In this [...] Read more.

Low-carbon micro-alloyed steel has become a wire material with great potential for further development due to its excellent comprehensive performance; however, there is still a lack of insight into the evolution of its electrical conductivity during annealing treatment after undergoing deformation. In this present contribution, we systematically explored the intrinsic correlation between the microstructural characteristics (including grain size evolution, dislocation density change, etc.) and performance indexes of cold-rolled high-conductivity high-strength steels and their mechanisms, using the annealing temperature, a key process parameter, as a variable. Characterization methods were used to comprehensively investigate the variation rule of the electrical conductivity of low-carbon micro-alloyed steels containing Ti-Nb elements under different annealing temperatures, as well as their influencing factors. The results show that for the ultra-low-carbon steel (0.002% C), the dislocation density continuously decreases with the increasing annealing temperature. Both experimental steels underwent complete recrystallization at 600 °C, with grain growth increasing at higher temperatures (with ultra-low-carbon steel being finer than low-carbon steel (0.075% C)). Dislocation density in ultra-low-carbon steel decreased steadily, whereas low-carbon steel exhibited an initial decline followed by an increase due to carbon-rich precipitate pinning. The yield ratio decreased with the annealing temperature, with optimal performance being at 700 °C for ultra-low-carbon steel (lowest resistivity: 13.75 μΩ/cm) and 800 °C for low-carbon steel (best conductivity: 14.66 μΩ/cm). Yield strength in ultra-low-carbon steel was dominated by grain and precipitation strengthening, while low-carbon steel relied more on precipitation and solid solution strengthening. Resistivity analysis confirmed that controlled precipitate size enhances conductivity. Full article

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

► Show Figures

Figure 1

10 pages, 4485 KiB

Open AccessEditor’s ChoiceArticle

Surface Morphology of 6-Inch SiC Single Crystals in Solution Growth on Si-Face, C-Face and (

10 \bar{1} \bar{2}

) Plane

by Gangqiang Liang, Jiayi Kuang, Yilin Su and Yuan Liu

Crystals 2025, 15(5), 472; https://doi.org/10.3390/cryst15050472 - 16 May 2025

Viewed by 477

Abstract

For solution growth of 6-inch 4H-SiC bulk crystals, the surface step morphology of the crystals grown on Si-face, C-face and (

10 \bar{1} \bar{2}

) plane was systematically characterized by laser confocal microscopy. The 2D-nucleation and step-bunching were likely to occur [...] Read more.

For solution growth of 6-inch 4H-SiC bulk crystals, the surface step morphology of the crystals grown on Si-face, C-face and (

10 \bar{1} \bar{2}

) plane was systematically characterized by laser confocal microscopy. The 2D-nucleation and step-bunching were likely to occur during the 30 h growth on Si-face, leading to a rough surface with a macro-step height over 60 μm. By contrast, the step heights were maintained at 0.1–1 μm during 60 h growth on C-face, exhibiting good morphological stability for long-term growth. Moreover, the SiC crystal grown on the (

10 \bar{1} \bar{2}

) plane illustrated its excellence in producing fine steps, which is attributed to the smaller interfacial energy between the solution and (

10 \bar{1} \bar{2}

) substrates, suggesting that it offers a better approach to growing SiC single bulk crystals. Full article

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

► Show Figures

Figure 1

28 pages, 11372 KiB

Open AccessEditor’s ChoiceArticle

Biological Control of Ca-Carbonate Crystal Microstructure and Texture: Adapting Crystal Morphology, Orientation, and Arrangement to Biomaterial Function

by Anna Sancho Vaquer, Erika Griesshaber, Juan Diego Castro-Claros, Carmen Salas, Xiaofei Yin, Antonio G. Checa and Wolfgang W. Schmahl

Crystals 2025, 15(5), 466; https://doi.org/10.3390/cryst15050466 - 15 May 2025

Viewed by 426

Abstract

The mineralized cover of chiton (Polyplacophora) soft tissue consists of aragonite, developed as shell-plates, girdle-scales, and girdle-spicules. This study characterizes crystallographic aspects of the girdle-spicules of the species Ischnochiton rissoi, Rhyssoplax olivacea, Acanthopleura vaillantii, and Acanthopleura spinosa. Spicule crystal [...] Read more.

The mineralized cover of chiton (Polyplacophora) soft tissue consists of aragonite, developed as shell-plates, girdle-scales, and girdle-spicules. This study characterizes crystallographic aspects of the girdle-spicules of the species Ischnochiton rissoi, Rhyssoplax olivacea, Acanthopleura vaillantii, and Acanthopleura spinosa. Spicule crystal arrangements and texture variations are described. Different misorientations between the spicule crystals are shown and are discussed with respect to the physical properties of the biomaterial. Characterization was performed with electron backscattered diffraction (EBSD), as well as with laser confocal and Field emission scanning electron microscopy (FE-SEM) imaging. All investigated species had porous spicules and distinct structural characteristics. Spicule crystal co-orientation strength was strongly increased for R. olivacea and I. rissoi, and it was almost random for A. vaillantii. R. olivacea, I. rissoi. A. spinosa spicule crystal texture was axial, whereas A. vaillantii spicule crystals were almost untextured. For all species investigated, spicule aragonite was twinned, as demonstrated with the strong 63°/64° peak in the misorientation angle distribution diagram, indicating a {110}-twin relationship. R. olivacea and I. rissoi spicules consisted of few twinned crystals and twin boundaries; A. vaillantii and A. spinosa spicules showed an abundance of twinned crystals and twin boundaries. We observed a difference in spicule dimension, morphology, arrangement on the girdle, and crystal organization for the investigated species, but always the generation of twinned aragonite. Full article

(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

► Show Figures

Figure 1

15 pages, 3922 KiB

Open AccessEditor’s ChoiceArticle

First-Principles Investigation of the Effect of Vacancy Defects and Carbon Impurities on Thermal Conductivity of Uranium Mononitride (UN)

by Yulin Lan, Tianhao Rui, Zhuangzhuang Ma, Linyuan Lu, Yunhao Wang, Yang Yu, Mingxuan Deng, Tianxing Lan, Zhekang Zhao, Junjie Wang, Congyi Li and Haibin Zhang

Crystals 2025, 15(5), 459; https://doi.org/10.3390/cryst15050459 - 14 May 2025

Viewed by 336

Abstract

Uranium mononitride (UN) is a promising nuclear fuel with a high melting point, high thermal conductivity, and low coefficient of thermal expansion. Theoretical studies of UN can provide insights on its thermal transport mechanism, which is of great significance for the design and [...] Read more.

Uranium mononitride (UN) is a promising nuclear fuel with a high melting point, high thermal conductivity, and low coefficient of thermal expansion. Theoretical studies of UN can provide insights on its thermal transport mechanism, which is of great significance for the design and application of UN fuel. During the processing and operation, crystal defects and impurities, such as vacancies and carbon impurities, potentially arise in the nuclear fuel, which probably affect the thermomechanical properties of UN. To figure out the effect of vacancy defects and carbon impurities on the thermal conductivity of UN, density functional theory and Boltzmann transport theory are applied to conduct a theoretical investigation on the mechanical and thermal properties of ideal and defective UN. The calculated results show that in the case of UN with a U or N vacancy, both the lattice and electronic thermal conductivity are decreased, compared with the ideal case. With a carbon atom occupying the N site in the lattice, the electronic thermal conductivity is reduced but the lattice thermal conductivity is increased. Combining the results of lattice and electronic thermal conductivity, the total thermal conductivities of three defective states are lower than the ideal UN. The thermal conductivities of UN with a U vacancy (13.91 W/mK), N vacancy (15.36 W/mK), and a carbon atom occupying the N site (15.14 W/mK) are, respectively, reduced by 25.7%, 18.0%, and 19.2%, in comparison with ideal result (18.73 W/mK) at 1000 K. Full article

► Show Figures

Figure 1

15 pages, 3639 KiB

Open AccessEditor’s ChoiceArticle

Prediction of Temperature Factors in Proteins: Effect of Data Pre-Processing and Experimental Conditions

by Jure Pražnikar

Crystals 2025, 15(5), 455; https://doi.org/10.3390/cryst15050455 - 12 May 2025

Viewed by 376

Abstract

The B-factor or temperature factor is one of the most important parameters in addition to the atomic coordinates, and which is refined during the determination of the protein structure and stored in the Protein Data Bank. It reflects the uncertainty of the atomic [...] Read more.

The B-factor or temperature factor is one of the most important parameters in addition to the atomic coordinates, and which is refined during the determination of the protein structure and stored in the Protein Data Bank. It reflects the uncertainty of the atomic positions and is closely linked to atomic flexibility. By using graphlet degree vectors as feature descriptors in a linear model—together with appropriate data transformation and consideration of various experimental factors—the model provides better prediction results. For example, the inclusion of crystal contacts in the linear model significantly improves the prediction accuracy. Since the distributions of the B-factors typically follow an inverse gamma distribution, applying a logarithmic transformation further improves the performance of the model. It has also been shown that large ligands, such as those found in protein–DNA complexes, have a significant impact on the quality of the prediction. A linear model based on graphlet degree vectors proves to be effective not only for the prediction of B-factors and the validation of deposited protein structures but also for the qualitative estimation of root-mean-square fluctuations derived from molecular dynamics. Full article

(This article belongs to the Section Macromolecular Crystals)

► Show Figures

Figure 1

15 pages, 4851 KiB

Open AccessEditor’s ChoiceArticle

Shape-Engineering and Mechanism Investigation of AgCl Microcrystals

by Chunli Cai, Qian Wang, Changsheng Yin, Xuhuan Li, Rong Yang, Xiaodong Shen and Wenbo Xin

Crystals 2025, 15(5), 451; https://doi.org/10.3390/cryst15050451 - 10 May 2025

Cited by 1 | Viewed by 304

Abstract

AgCl microcrystals are used in visible light photocatalysis. However, their properties depend strongly on the morphology of the crystals and the degree of exposure of the crystal planes. Despite extensive research conducted on the synthesis of AgCl microcrystals, the majority of existing studies [...] Read more.

AgCl microcrystals are used in visible light photocatalysis. However, their properties depend strongly on the morphology of the crystals and the degree of exposure of the crystal planes. Despite extensive research conducted on the synthesis of AgCl microcrystals, the majority of existing studies have focused on the stable growth of crystals. The role of Cl⁻ ions concentration as a key factor controlling the microcrystals morphology has not been fully explored, which limits the precise tuning of the morphology of AgCl microcrystals. In this study, AgCl microcrystals with controllable morphology are successfully synthesized by a facile solvothermal method. During the preparation process, ethylene glycol (EG) is utilized as a solvent, while polyvinylpyrrolidone (PVP) is employed as a surfactant. We systematically investigate the etching mechanism of AgCl microcrystals by analyzing the effect of sodium chloride (NaCl) concentration on their morphology. This investigation involves the integration of diverse characterization methods, including scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and geometrical struc-ture analysis. The results demonstrate that Cl⁻ functions as both a surfactant, thereby promoting the nucleation of cubic microcrystals, and as an etchant, selectively etching the crystal surface. The order of selective etching on the crystal surface follows (100) planes > (110) planes > (111) planes. Based on this new mechanism, AgCl microcrystals with various morphologies, such as cube, octopod and dendrite, are successfully prepared, which provides a new idea for the precise design of noble metal halide microcrystals. Full article

(This article belongs to the Section Crystal Engineering)

► Show Figures

Figure 1

22 pages, 6877 KiB

Open AccessEditor’s ChoiceArticle

Inspection of Bulk Crystals for Quality Control in Crystal Growth: Assessment of High-Energy X-Ray Transmission Topography and Back-Reflection Topography Pinpointed for Physical Vapor Transport-Grown Aluminum Nitride

by Roland Weingärtner, Boris Epelbaum, Andreas Lesnik, Gleb Lukin, Stephan Müller, Leon Schiller, Elke Meissner, Matthias Weisser and Sven Besendörfer

Crystals 2025, 15(5), 449; https://doi.org/10.3390/cryst15050449 - 9 May 2025

Viewed by 495

Abstract

A comprehensive X-ray topography analysis of two selected aluminum nitride (AlN) bulk crystals is presented. We compare surface inspection X-ray topography in back-reflection geometry with high-energy transmission topography in the Lang and Laue configuration using the monochromatic K_α1 excitation wavelength of copper, [...] Read more.

A comprehensive X-ray topography analysis of two selected aluminum nitride (AlN) bulk crystals is presented. We compare surface inspection X-ray topography in back-reflection geometry with high-energy transmission topography in the Lang and Laue configuration using the monochromatic K_α1 excitation wavelength of copper, silver, and tungsten, respectively. A detailed comparison of the results allows the assessment of both the high- and low-energy X-ray topography methods with respect to performance and structural information, giving essential feedback for crystal growth. This is demonstrated for two selected AlN freestanding faceted crystals up to 8 mm in thickness grown in all directions using the physical vapor transport (PVT) method. Structural defects of all facets of the crystals are determined using the X-ray topography in back-reflection geometry. The mean threading dislocation densities are 480 ± 30 cm⁻² for both crystals of either the Al- or N-face. Clustering of dislocations could be observed. The m-facets show the presence of basal plane dislocations and their accumulation as clusters. The integral transmission topographs of the

10 \bar{1} 0

(m-plane) reflection family show that basal plane dislocations of the screw type in

\frac{1}{3} ⟨\bar{1} 2 \bar{1} 0⟩

directions decorate threading dislocation clusters. Three-dimensional section transmission topography reveals that the basal plane dislocation clusters mainly originate at the seed boundary and propagate in the

\frac{1}{3} ⟨\bar{1} 2 \bar{1} 0⟩

direction along the growth front. In newly laterally grown material, the Borrmann effect has been observed for the first time in PVT-grown bulk AlN, indicating very high structural perfection of the crystalline material in this region. This agrees with a low mean FWHM of 10.6 arcsec of the

10 \bar{1} 0

reflection determined through focused high-energy Laue transmission mappings. The latter method also opens the analysis of the

∆ 2 θ

-shift correlated to the residual stress distribution inside the bulk crystal, which is dominated by dislocation clusters. Contrary to Lang transmission topography, the de-focused high-energy Laue transmission penetrates the 8 mm-thick crystal enabling a defect analysis in the bulk. Full article

(This article belongs to the Section Crystal Engineering)

► Show Figures

Figure 1

11 pages, 2623 KiB

Open AccessEditor’s ChoiceArticle

Structural Analysis of PlyKp104, a Novel Phage Endoysin

by Jung-Min Choi

Crystals 2025, 15(5), 448; https://doi.org/10.3390/cryst15050448 - 9 May 2025

Viewed by 325

Abstract

Antibiotic resistance has emerged as a critical global public health challenge, prompting increased interest in non-antibiotic antimicrobial strategies such as bacteriophage-derived endolysins. Although endolysins possess strong lytic potential, their application to Gram-negative bacteria remains limited due to the outer membrane barrier. PlyKp104 is [...] Read more.

Antibiotic resistance has emerged as a critical global public health challenge, prompting increased interest in non-antibiotic antimicrobial strategies such as bacteriophage-derived endolysins. Although endolysins possess strong lytic potential, their application to Gram-negative bacteria remains limited due to the outer membrane barrier. PlyKp104 is a recently identified phage-derived endolysin that exhibits lytic activity against Gram-negative bacteria without the aid of membrane permeabilizers. In this study, the crystal structure of PlyKp104 was determined at a resolution of 1.85 Å. PlyKp104 consists solely of a catalytic SLT domain, and structure-based analysis revealed a putative active site and key structural features associated with substrate binding. Comparative analysis with homologous structures suggested that PlyKp104 belongs to lytic transglycosylase family 1. B-factor analysis and hydrophobic interaction mapping indicated that the domain exhibits high structural stability, supported by conserved hydrophobic residues clustered in motifs I and II. During structure determination, an unidentified electron density was consistently observed near a neutral, hydrophobic surface region. Its shape and environment suggest the presence of a lipid-like molecule, implying a potential lipid-binding site. These findings provide structural insight into PlyKp104 and contribute to the understanding of endolysin mechanisms against Gram-negative bacteria, with implications for future protein engineering efforts. Full article

(This article belongs to the Special Issue Crystallography of Enzymes)

► Show Figures

Figure 1

16 pages, 7322 KiB

Open AccessEditor’s ChoiceArticle

Structural Study of Thermostable Ginsenoside β-Glucosidase from Caldicellulosiruptor bescii

by Jung-Min Choi

Crystals 2025, 15(5), 447; https://doi.org/10.3390/cryst15050447 - 9 May 2025

Viewed by 445

Abstract

Protopanaxadiol-type ginsenosides, the major bioactive components of Panax ginseng, exhibit diverse pharmacological activities, but suffer from low oral bioavailability due to poor water solubility and membrane permeability. Enzymatic deglycosylation has emerged as an effective strategy to enhance their therapeutic potential; however, most [...] Read more.

Protopanaxadiol-type ginsenosides, the major bioactive components of Panax ginseng, exhibit diverse pharmacological activities, but suffer from low oral bioavailability due to poor water solubility and membrane permeability. Enzymatic deglycosylation has emerged as an effective strategy to enhance their therapeutic potential; however, most glucosidases lack sufficient thermostability for industrial applications. A β-glucosidase from the thermophilic bacterium Caldicellulosiruptor bescii (CbBGL) has demonstrated efficient conversion of major ginsenosides into compound K at elevated temperatures. In this study, the high-resolution crystal structure of CbBGL was determined at 1.9 Å. Structural analysis revealed that CbBGL adopts a classical (α/β)₈ TIM barrel fold and functions as a homodimer. Comparative studies with other glucosidases highlighted structural features contributing to its thermostability, including moderate B-factor distribution and a limited hydrogen bond network. Docking analyses revealed a narrow, inverted conical substrate-binding cleft, which imposes specific binding orientations and underlies the enzyme’s stepwise deglycosylation mechanism. These insights provide a structural basis for CbBGL’s thermal resilience and substrate specificity, offering a valuable platform for the rational engineering of glucosidases in ginsenoside bioconversion processes. Full article

(This article belongs to the Special Issue Crystallography of Enzymes)

► Show Figures

Figure 1

15 pages, 4412 KiB

Open AccessEditor’s ChoiceArticle

Evolution of Phonon Spectral Energy Density in Superlattice Structures

by Milad Nasiri and Yan Wang

Crystals 2025, 15(5), 446; https://doi.org/10.3390/cryst15050446 - 9 May 2025

Viewed by 476

Abstract

Superlattices are a distinctive class of artificial nanostructures formed by the periodic stacking of two or more materials. The high density of interfaces in these structures often gives rise to exotic physical properties. In the context of thermal transport, it is well established [...] Read more.

Superlattices are a distinctive class of artificial nanostructures formed by the periodic stacking of two or more materials. The high density of interfaces in these structures often gives rise to exotic physical properties. In the context of thermal transport, it is well established that such interfaces can significantly scatter particle-like phonons while also inducing constructive or destructive interference in wave-like phonons, depending on the relationship between the phonons’ coherence lengths and the superlattice’s period thickness. In this work, we systematically investigate the effect of temperature on the spectral energy density of phonon modes in superlattices. Additionally, we examine how variations in superlattice period thickness influence phonon lifetimes and energy density. Our findings provide critical insights into the spectral phonon properties of superlattices, particularly in terms of their coherence and lifetimes. Full article

(This article belongs to the Special Issue Metamaterials and Their Devices, Second Edition)

► Show Figures

Figure 1

13 pages, 2056 KiB

Open AccessEditor’s ChoiceArticle

Finding Crystal Orientations in Uniplanar Textures

by Josef Simbrunner, Fabian Gasser, Sanjay John, Ingo Salzmann and Roland Resel

Crystals 2025, 15(5), 443; https://doi.org/10.3390/cryst15050443 - 8 May 2025

Viewed by 344

Abstract

The crystallization of molecular materials on isotropic substrates typically results in a so-called fiber or uniplanar texture that comprises crystallites that share a common fiber axis perpendicular to the substrate surface, but that are azimuthally randomly oriented. The crystallographic characterization of such films [...] Read more.

The crystallization of molecular materials on isotropic substrates typically results in a so-called fiber or uniplanar texture that comprises crystallites that share a common fiber axis perpendicular to the substrate surface, but that are azimuthally randomly oriented. The crystallographic characterization of such films is commonly performed by grazing-incidence X-ray diffraction. Thereby, two-dimensional reciprocal space maps are obtained that incorporate the in-plane component q_xy and the out-of-plane component q_z for each diffraction peak. The exact position of each diffraction peak depends on the crystallographic lattice and on the orientation of the unit cell relative to the substrate surface. The unit cell orientation can be characterized either by two rotation angles or by the Miller indices of the crystallographic plane (contact plane) parallel to the substrate surface. Equations are derived that allow the calculation of these orientation parameters and describe the relations between them. Depending on the crystallographic system of the underlying unit cell and its contact plane, manifold possible orientations may exist due to the multiplicity of planes contributing to the same reflections. Examples based on molecular crystals of pentacenequinone, diindenoperylene, and binaphthalene are discussed, which are illustrative examples comprising triclinic, monoclinic, and tetragonal unit cells having two, four, and sixteen possible crystal orientations, respectively. Full article

► Show Figures

Figure 1

15 pages, 4952 KiB

Open AccessEditor’s ChoiceArticle

Optimized Breakdown Strength and Crystal Structure for Boosting the Energy Storage Performance of Niobate-Based Glass Ceramics via a B-Site Substitution Strategy

by Kexin Gao, Fei Shang, Yaoyi Qin and Guohua Chen

Crystals 2025, 15(5), 444; https://doi.org/10.3390/cryst15050444 - 8 May 2025

Cited by 1 | Viewed by 426

Abstract

Based on the B-site modification strategy, excellent energy storage properties were achieved in this work by substituting Nb with Ta of the same valence in niobate-based glass ceramics. Ta substitution was found to lead to the transformation of crystal structures, and the space [...] Read more.

Based on the B-site modification strategy, excellent energy storage properties were achieved in this work by substituting Nb with Ta of the same valence in niobate-based glass ceramics. Ta substitution was found to lead to the transformation of crystal structures, and the space point group evolved from the non-centrosymmetric P4bm to the centrosymmetric P4/mbm, resulting in a transition from relaxor ferroelectric to paraelectric glass ceramics. Furthermore, the addition of Ta led to a significant decrease in grain size and interfacial activation energy, as well as an increase in the optical band gap, resulting in a dramatic increase in BDS from 800 kV/cm to 1300 kV/cm. The KBSN-4.0mol%Ta₂O₅ glass ceramic exhibited optimal energy storage properties, including a discharge energy density of ~5.62 J/cm³ and a superfast discharge rate of ~9.7 ns, resulting in an ultrahigh discharge power density of about ~1296.9 MW/cm³ at 1300 kV/cm. Furthermore, this KBSN-Ta glass ceramic also displayed good thermal stability over a temperature range of 20–120 °C, with the W_d decreasing by 9.0% at 600 kV/cm. B-site modification engineering in glass ceramics has proved to be an important way to effectively optimize energy storage performance. Full article

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

► Show Figures

Graphical abstract

12 pages, 2166 KiB

Open AccessEditor’s ChoiceArticle

¹¹⁹Sn Element-Specific Phonon Density of States of BaSnO₃

by Alexey Rulev, Hongxin Wang, Selma Erat, Murat Aycibin, Daniel Rentsch, Vladimir Pomjakushin, Stephen P. Cramer, Qianli Chen, Nobumoto Nagasawa, Yoshitaka Yoda and Artur Braun

Crystals 2025, 15(5), 440; https://doi.org/10.3390/cryst15050440 - 5 May 2025

Viewed by 312

Abstract

Vibration spectroscopy is routinely used in analytical chemistry for molecular speciation. Less common is its use in studying the dynamics of reaction and transport processes. A shortcoming of vibration spectroscopies is that they are not inherently specific to chemical elements. Progress in synchrotron [...] Read more.

Vibration spectroscopy is routinely used in analytical chemistry for molecular speciation. Less common is its use in studying the dynamics of reaction and transport processes. A shortcoming of vibration spectroscopies is that they are not inherently specific to chemical elements. Progress in synchrotron radiation-based X-ray technology has developed nuclear resonance vibration spectroscopy (NRVS), which can be used to produce element-specific vibration spectra and partial vibrational density of states (PVDOS), provided the material under investigation contains a Mössbauer-active element. While the method has been recently used successfully for protein spectroscopy, fewer studies have been conducted for condensed matter. We have employed NRVS on the BaSnO₃ perovskite structure, which is a model compound for ceramic proton conductors in intermediate temperature fuel cells. Since we used ¹¹⁹Sn as a Mössbauer isotope, the derived experimental PVDOS is specific to the element Sn in BaSnO₃. We show how this phonon DOS is used as an experimental anchor for the interpretation of the DFT-calculated PVDOS of BaSnO₃. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

► Show Figures

Figure 1

10 pages, 4289 KiB

Open AccessEditor’s ChoiceArticle

Theoretical Investigation of Chromium Separation from Chromates Through Photon–Phonon Resonant Absorption

by Mingyan Xie, Haoxin Ren, Yuanda Huang, Peilin Li, Yining Li, Yawen Li, Yuqi Xia and Peng Zhang

Crystals 2025, 15(5), 437; https://doi.org/10.3390/cryst15050437 - 3 May 2025

Cited by 1 | Viewed by 492

Abstract

Chromium (Cr) is a vital metal utilized in materials physics, healthcare, and various other domains. In this study, we propose an eco-friendly method for separating Cr from potassium chromate (K₂CrO₄) based on photon–phonon resonance absorption theory. Using first-principles density [...] Read more.

Chromium (Cr) is a vital metal utilized in materials physics, healthcare, and various other domains. In this study, we propose an eco-friendly method for separating Cr from potassium chromate (K₂CrO₄) based on photon–phonon resonance absorption theory. Using first-principles density functional theory calculations, we obtained the Raman and infrared spectra of K₂CrO₄ and assigned the vibrational modes to the peaks observed in the experimental spectra. We confirmed that the strongest infrared absorption peak corresponds to the Cr-O bond stretching vibration theoretically located at 931 cm⁻¹. We propose employing a high-power terahertz laser at this resonant frequency for photothermal energy transfer. This approach is expected to enhance the efficiency of separating Cr from K₂CrO₄. Experimental investigations are expected in the future. Full article

(This article belongs to the Special Issue Laser–Material Interaction: Principles, Phenomena, and Applications)

► Show Figures

Figure 1

9 pages, 1803 KiB

Open AccessEditor’s ChoiceArticle

Inelastic Electron Tunneling Spectroscopy of Aryl Alkane Molecular Junction Devices with Graphene Electrodes

by Hyunwook Song

Crystals 2025, 15(5), 433; https://doi.org/10.3390/cryst15050433 - 1 May 2025

Viewed by 328

Abstract

We present a comprehensive vibrational spectroscopic analysis of vertical molecular junction devices constructed using single-layer graphene electrodes separated by an aryl alkane monolayer. In this work, inelastic electron tunneling spectroscopy (IETS) is employed to probe molecular vibrations within the junction, providing an in [...] Read more.

We present a comprehensive vibrational spectroscopic analysis of vertical molecular junction devices constructed using single-layer graphene electrodes separated by an aryl alkane monolayer. In this work, inelastic electron tunneling spectroscopy (IETS) is employed to probe molecular vibrations within the junction, providing an in situ fingerprint of the molecules. Graphene has emerged as a promising electrode material for molecular electronics due to its atomically thin, mechanically robust nature and ability to form stable contacts. However, prior to this study, the vibrational spectra of molecules in graphene-based molecular junctions had not been fully explored. Here, we demonstrate that vertically stacked graphene electrodes can be used to form stable and reproducible molecular junctions that yield well-resolved IETS signatures. The observed IETS spectra exhibit distinct peaks corresponding to the vibrational modes of the sandwiched aryl alkane molecules, and all major features are assigned through density functional theory calculations of molecular vibrational modes. Furthermore, by analyzing the broadening of IETS peaks with temperature and AC modulation amplitude, we extract intrinsic vibrational linewidths, confirming that the spectral features originate from the molecular junction itself rather than extrinsic noise or instrumental artifacts. These findings conclusively verify the presence of the molecular layer between graphene electrodes as the charge transport pathway and highlight the potential of graphene–molecule–graphene junctions for fundamental studies in molecular electronics. Full article

(This article belongs to the Special Issue Advances in Multifunctional Materials and Structures)

► Show Figures

Figure 1

19 pages, 9508 KiB

Open AccessEditor’s ChoiceArticle

Preparation, Microstructure, and Properties of Solar Energy-Absorbing and -Storing Integrated Forsterite-Based Ceramics

by Xiaohong Xu, Yuntian Li, Tiantian Cheng, Jianfeng Wu, Yaqiang Shen, Saixi Qiu and Jiaqi Yu

Crystals 2025, 15(5), 427; https://doi.org/10.3390/cryst15050427 - 30 Apr 2025

Viewed by 340

Abstract

Solar energy-absorbing and -storing integrated ceramics are a new type of material that absorbs sunlight and stores it as heat energy, with properties such as high absorptivity, high thermal storage density, and high temperature stability. In this study, forsterite ceramics were prepared from [...] Read more.

Solar energy-absorbing and -storing integrated ceramics are a new type of material that absorbs sunlight and stores it as heat energy, with properties such as high absorptivity, high thermal storage density, and high temperature stability. In this study, forsterite ceramics were prepared from fused magnesia, quartz, α-Al₂O₃, and Sm₂O₃, and concurrently, two additives of Fe₂O₃ and CuO were doped to improve the absorptivity, and the effects of the composite additives on the performance of forsterite ceramics were investigated. The results showed that the optimal Fe₂O₃/CuO content ratio was 8:2, at which time the apparent porosity, bulk density, and thermal storage density of the sample were 0.21%, 3.08 g/cm³, and 1516.71 kJ/kg (1000 °C), respectively. After 30 thermal shock cycles, the precipitation of samarium silicate in the samples resulted in a tighter grain bonding, increased the bending strength by 70.6%, and exhibited excellent thermal shock resistance. The solar absorptivity reached 93.80% in the 0.3–2.5 μm wavelength range. Fe₂O₃ doping replaced part of the positions of Al³⁺ in MgAl₂O₄ to form MgFe_0.6Al_1.4O₄ phase. This replacement caused lattice distortion, which triggered electronic transition and augmented the intrinsic absorption capacity, thereby enhancing the sample’s absorptivity. CuO’s low reflectivity across the spectrum further reduced sample reflectivity. Full article

(This article belongs to the Section Polycrystalline Ceramics)

► Show Figures

Figure 1

14 pages, 5493 KiB

Open AccessEditor’s ChoiceArticle

Evolution of Microstructure, Tensile Mechanical and Corrosion Properties of a Novel Designed TRIP-Aided Economical 19Cr Duplex Stainless Steel After Aging Treatment

by Xi Shi, Shan Liu, Shuaiwei Chen, Qingxuan Ran, Bo Liang and Xiaoliang Yan

Crystals 2025, 15(5), 419; https://doi.org/10.3390/cryst15050419 - 29 Apr 2025

Viewed by 269

Abstract

In this experiment, a novel designed Mn-N-bearing, nearly Ni-free, TRIP-aided economical 19Cr (Fe-18.9Cr-10.1Mn-0.3Ni-0.26N-0.03C) duplex stainless steel (DSS) was prepared, and it exhibited a good combination of strength and toughness after suitable solution treatment, showing good application potential. The deformation mechanisms of ferrite and [...] Read more.

In this experiment, a novel designed Mn-N-bearing, nearly Ni-free, TRIP-aided economical 19Cr (Fe-18.9Cr-10.1Mn-0.3Ni-0.26N-0.03C) duplex stainless steel (DSS) was prepared, and it exhibited a good combination of strength and toughness after suitable solution treatment, showing good application potential. The deformation mechanisms of ferrite and austenite are different during tensile deformation at room temperature: the ferrite phase was deformed by a dislocation slip mechanism and formed a cell structure due to its higher stacking fault energy; the lower stacking fault energy of austenite resulted in a strain-induced martensite phase transformation mechanism. With an increase in aging time from 1 h to 7 h at 750 °C in air, the σ phase precipitates in the ferrite triple grain boundary junction, which leads to an increase in ultimate tensile strength, acts as an obstacle to the dislocation motion and decreases the ductility, deteriorating the pitting corrosion resistance in 3.5 wt.% NaCl solution at the same time. The σ phase precipitation behavior does not alter the deformation mechanism of the phases of the solution-treated TRIP-aided economical DSS. Full article

(This article belongs to the Special Issue Microstructure and Properties of Steels and Other Structural Alloys, Second Edition)

► Show Figures

Figure 1

20 pages, 2259 KiB

Open AccessEditor’s ChoiceArticle

Temperature-Controlled Defective Phononic Crystals with Shape Memory Alloys for Tunable Ultrasonic Sensors

by Soo-Ho Jo

Crystals 2025, 15(5), 412; https://doi.org/10.3390/cryst15050412 - 28 Apr 2025

Cited by 2 | Viewed by 432

Abstract

Phononic crystals (PnCs) have garnered significant interest owing to their ability to manipulate wave propagation, particularly through phononic band gaps and defect modes. However, conventional defective PnCs are limited by their fixed defect-band frequencies, which restricts their adaptability to dynamic environments. This study [...] Read more.

Phononic crystals (PnCs) have garnered significant interest owing to their ability to manipulate wave propagation, particularly through phononic band gaps and defect modes. However, conventional defective PnCs are limited by their fixed defect-band frequencies, which restricts their adaptability to dynamic environments. This study introduces a novel approach for temperature-controlled tunability of defective PnCs by integrating shape memory alloys (SMAs) into defect regions. The reversible phase transformations of SMAs, driven by temperature variations, induce significant changes in their mechanical properties, enabling real-time adjustment of defect-band frequencies. An analytical model is developed to predict the relationship between the temperature-modulated material properties and defect-band shifts, which is validated through numerical simulations. The results demonstrate that defect-band frequencies can be dynamically controlled within a specified range, thereby enhancing the operational bandwidth of the ultrasonic sensors. Additionally, sensing-performance analysis confirms that while defect-band frequencies shift with temperature, the output voltage of the sensors remains stable, ensuring reliable sensitivity across varying conditions. This study represents a significant advancement in tunable PnC technology, paving the way for next-generation ultrasonic sensors with enhanced adaptability and reliability in complex environments. Full article

(This article belongs to the Special Issue Research and Applications of Acoustic Metamaterials)

► Show Figures

Figure 1

15 pages, 2675 KiB

Open AccessEditor’s ChoiceArticle

Crystal Chemistry and Genetic Implications of Pink Tourmalines from Distinct Pegmatite Provinces

by Floriana Rizzo, Ferdinando Bosi, Gioacchino Tempesta, Federica Iommazzo and Giovanna Agrosì

Crystals 2025, 15(5), 415; https://doi.org/10.3390/cryst15050415 - 28 Apr 2025

Viewed by 366

Abstract

Borosilicate minerals of the tourmaline supergroup are valuable both for collectors and for geological research, as their chemical composition reflects the growth-medium conditions and their evolution. Tourmalines show a wide compositional variability, with pink tourmalines being particularly prized as gemstones. This study examines [...] Read more.

Borosilicate minerals of the tourmaline supergroup are valuable both for collectors and for geological research, as their chemical composition reflects the growth-medium conditions and their evolution. Tourmalines show a wide compositional variability, with pink tourmalines being particularly prized as gemstones. This study examines the crystal chemistry of pink tourmalines from Cruzeiro (Brazil), Nuristan (Afghanistan), and Malkhan (Russia) using Electron Microprobe Analysis, Micro Laser Induced Breakdown Spectroscopy (LIBS), and Single Crystal X-ray Diffraction. The results show that the pink tourmalines are Mn-rich elbaite, with the pink coloration linked to Mn at the Y site, indicating crystallization from Mn-rich pegmatitic fluids. LIBS spectra suggest a Li-rich pegmatite origin. The samples show differences: Cruzeiro exhibits strong chemical zoning, Nuristan has a uniform composition, and Malkhan shows slight zoning with high F content. A comparison with a pink tourmaline from Anjanabonoina (Madagascar) reveals that it is Ca-rich, belonging to the calcic group and crystallizing in an open system influenced by external Ca-rich fluids, contrasting with the closed system of the samples from Cruzeiro and Nuristan. The sample from Malkhan shows an anomalous chemical variation of Ca and requires further investigation. Full article

(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

► Show Figures

Figure 1

11 pages, 1890 KiB

Open AccessEditor’s ChoiceArticle

First-Principles Study on the Migration and Release Properties of Xe on the Surface of Uranium Mononitride

by Tianhao Rui, Yulin Lan, Zhuangzhuang Ma, Linyuan Lu, Yunhao Wang, Yang Yu, Mingxuan Deng, Tianxing Lan, Zhekang Zhao, Junjie Wang, Congyi Li and Haibin Zhang

Crystals 2025, 15(5), 409; https://doi.org/10.3390/cryst15050409 - 27 Apr 2025

Viewed by 326

Abstract

The fission gas uranium mononitride (UN) causes swelling and affects the properties of fission fuel. Since surface behavior is closely related to the release of gases, it is crucial to study the properties of Xe on the UN surface. Density functional theory was [...] Read more.

The fission gas uranium mononitride (UN) causes swelling and affects the properties of fission fuel. Since surface behavior is closely related to the release of gases, it is crucial to study the properties of Xe on the UN surface. Density functional theory was used to study the properties of Xe gas on the UN(001) surface and subsurface layers. Different bulk and surface models of UN were established, and the formation energies of bulk and surface defects, as well as the incorporation energy of surface Xe, were calculated. Differential charge density maps were generated, and the analysis revealed that the migration of Xe atoms on the surface predominantly occurs through a vacancy mechanism. Furthermore, Xe atoms located in the subsurface and interstitial positions are less likely to escape from the surface due to the influence of surrounding atoms. Finally, the Climbing Image Nudged Elastic Band method was employed to calculate migration pathways and the associated migration energies. The modelling results indicated that surface Xe atoms’ migration exhibits a vacancy-assisted mechanism, while surface and subsurface U-vacancies on the UN surface may promote the diffusion of fission gas atoms. Full article

► Show Figures

Figure 1

19 pages, 6524 KiB

Open AccessEditor’s ChoiceArticle

Hydrogen-Bonded Ladder Motifs in Naphthalene Dicarboxamides: Influence of Linear vs. Angular Amide Orientation

by Abdulrahman Mohabbat, István Boldog, Takin Haj Hassani Sohi, Nils Reistel, Philipp Seiffert and Christoph Janiak

Crystals 2025, 15(5), 406; https://doi.org/10.3390/cryst15050406 - 26 Apr 2025

Viewed by 584

Abstract

The crystal structures of naphthalene dicarboxamides, namely 1,4-naphthalene dicarboxamide (1,4-NDA), 2,6-naphthalene dicarboxamide (2,6-NDA), and 2,7-naphthalene dicarboxamide (2,7-NDA), are presented for the first time, along with an analysis of their supramolecular organization. The compounds, obtained in single-crystalline form via solvothermal crystallization from methanol, are [...] Read more.

The crystal structures of naphthalene dicarboxamides, namely 1,4-naphthalene dicarboxamide (1,4-NDA), 2,6-naphthalene dicarboxamide (2,6-NDA), and 2,7-naphthalene dicarboxamide (2,7-NDA), are presented for the first time, along with an analysis of their supramolecular organization. The compounds, obtained in single-crystalline form via solvothermal crystallization from methanol, are stable in air to near 350 °C and have melting points above 300 °C. In their densely packed structures (ρ = 1.43–1.47 cm³g⁻¹) the combination of

C_{1}^{1}

(4) chains and

R_{2}^{2}

(8) rings generates one-dimensional hydrogen-bonded ladders, with an additional

R_{4}^{2}

(8) pattern. The amide groups and the naphthalene rings form dihedral angles between 22° and 40°. Neighboring H-bond ladders run parallel in 1,4-NDA and 2,6-NDA and are connected by means of the naphthalenedyil cores so that two-dimensional (2D) H-bonded sheets are obtained. Except for a weak intra-sheet π–π stacking in 1,4-NDA, there are no π–π stacking and C–H⋯π interactions. The

R_{2}^{2}

(8) rings act as four-connected nodes, leading to the formation of two-dimensional H-bonded planar sheets with sql topology for the nearly linear dicarboxamides 1,4-NDA and 2,6-NDA and cds topology for the angular 2,7-NDA. Hirshfeld surface analysis and NCI plots provide additional insight into the H-bonding interactions. Full article

(This article belongs to the Section Crystal Engineering)

► Show Figures

Graphical abstract

15 pages, 2187 KiB

Open AccessEditor’s ChoiceReview

Sustainable Strategies for Wine Colloidal Stability: Innovations in Potassium Bitartrate Crystallization Control

by Yuhan Zhang

Crystals 2025, 15(5), 401; https://doi.org/10.3390/cryst15050401 - 25 Apr 2025

Viewed by 586

Abstract

Potassium bitartrate (KHT) crystallization, as the dominant factor compromising wine colloidal stability, necessitates advanced control strategies beyond conventional thermodynamic approaches. The formation of tartrate crystals is influenced by various factors, including temperature, pH, and the concentration of tartrate salts. Traditional methods of tartrate [...] Read more.

Potassium bitartrate (KHT) crystallization, as the dominant factor compromising wine colloidal stability, necessitates advanced control strategies beyond conventional thermodynamic approaches. The formation of tartrate crystals is influenced by various factors, including temperature, pH, and the concentration of tartrate salts. Traditional methods of tartrate stabilization, such as cold stabilization and ion-exchange resins, while effective, are associated with high energy consumption and significant environmental impact. In recent years, with the growing emphasis on green and sustainable development, researchers have begun exploring more environmentally friendly innovative technologies. This review examines the factors affecting tartrate crystallization and their implications for wine quality, detailing traditional stabilization techniques as well as newer methods involving protective colloids and stabilizers. Special attention is given to recent advancements in green technologies, such as plasma surface modification, the use of zeolites as wine processing aids, and the synergistic application of algal polysaccharides. Finally, the paper outlines future directions for tartrate stabilization technology, underscoring the importance of green and sustainable practices in the wine industry. Full article

(This article belongs to the Section Liquid Crystals)

► Show Figures

Figure 1

19 pages, 4638 KiB

Open AccessEditor’s ChoiceArticle

Structural and Optical Properties of Defected and Exotic Calcium Monochalcogenide Nanoparticles: Insights from DFT and TD-DFT Calculations

by Panagiotis G. Moustris, Alexandros G. Chronis, Fotios I. Michos, Nikos Aravantinos-Zafiris and Mihail M. Sigalas

Crystals 2025, 15(5), 392; https://doi.org/10.3390/cryst15050392 - 23 Apr 2025

Viewed by 587

Abstract

In this work, the structural and optical properties of calcium monochalcogenide nanoparticles were numerically examined by using Density Functional Theory and Time Dependent Density Functional Theory. The composition of the examined nanoparticles was obtained from an initial cubic-like building block of the form [...] Read more.

In this work, the structural and optical properties of calcium monochalcogenide nanoparticles were numerically examined by using Density Functional Theory and Time Dependent Density Functional Theory. The composition of the examined nanoparticles was obtained from an initial cubic-like building block of the form Ca₄Y₄, where Y could be one of the chalcogen elements sulfur, selenium, and tellurium, after its proper numerical examination to check their structural stability. The examined nanoparticles were then created from these initial cubic-like building blocks after their elongation along one, two, and three perpendicular directions. Τhe Absorption Spectrum, the Binding Energy, together with the highest occupied-lowest unoccupied molecular orbital (HOMO-LUMO) gap, were included in the calculations of the studied calcium monochalcogenides. The calculations provided numerical evidence regarding the existence of stable structures for a wide range of morphologies. In addition, the examination of the properties of such nanostructures after placing different kinds of defects was also included in the calculations, thus leading to new groups of nanoparticles with several potential uses in technological applications, such as hydrogen storage, CO₂ capture, and ultraviolet-responsive devices. Full article

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

► Show Figures

Figure 1

26 pages, 5096 KiB

Open AccessEditor’s ChoiceArticle

Chromone-Based Copper(II) Complexes as Potential Antitumour Agents: Synthesis, Chemical Characterisation and In Vitro Biological Evaluation

by Nikolina Filipović, Tomislav Balić, Martina Medvidović-Kosanović, Dominik Goman, Berislav Marković, Dalibor Tatar, Sunčica Roca and Katarina Mišković Špoljarić

Crystals 2025, 15(5), 389; https://doi.org/10.3390/cryst15050389 - 23 Apr 2025

Viewed by 505

Abstract

Three new complexes of copper(II) and chromone-2-carboxylic acid, a ligand from the group of hydroxypyrones, were synthesised according to the principles of green chemistry. The complexes were characterised by FT–IR and NMR spectroscopy, thermal and electrochemical analysis, and their structures are proposed. The [...] Read more.

Three new complexes of copper(II) and chromone-2-carboxylic acid, a ligand from the group of hydroxypyrones, were synthesised according to the principles of green chemistry. The complexes were characterised by FT–IR and NMR spectroscopy, thermal and electrochemical analysis, and their structures are proposed. The results show the formation of mononuclear (1) and dinuclear hydroxo-bridged dinuclear copper(II) complexes (2 and 3). The results of cyclic voltammetry show that the copper in all complexes is in the +2-oxidation state. The antiproliferative activity was determined by MTT assay on 2D cell models in vitro on seven cell lines. The activity spectrum of complexes 1–3 ranged from the highest to the lowest value in the tumour cell lines tested, in the following order: Hep G2 > NCI-H358 > HT-29 > KATO III > MDA-MB 231 > Caco-2. The most effective concentration was 10⁻⁵ mol dm⁻³, which suppressed the growth of Hep G2 cells as follows: 69.5% (1), 64.8% (2) and 64% (3). The calculated selectivity index clearly shows that Hep G2 is the most sensitive cell line to copper complexes (SI = 1.623 (1); 1.557 (2), 1.431 (3). Full article

(This article belongs to the Special Issue Green Approach in Synthesis of Bio-Inspired Materials (Second Edition))

► Show Figures

Figure 1

14 pages, 6074 KiB

Open AccessEditor’s ChoiceArticle

Cu₂S Nanocrystals and Their Superlattices

by Samuel Fuentes, Ryan Hart, Juan Ramirez, Aditi Mulgaonkar, Rainie Luo, Brady Killham, Sashi Debnath, Yunfeng Wang, Xiankai Sun, Jiechao Jiang and Yaowu Hao

Crystals 2025, 15(5), 387; https://doi.org/10.3390/cryst15050387 - 23 Apr 2025

Viewed by 452

Abstract

We report the successful synthesis of monodispersed Cu₂S nanocrystals and the subsequent formation of highly ordered nanocrystal superlattices. The synthesis is performed under ambient air conditions using simple experimental setups, making the process both accessible and scalable. By systematically tuning the [...] Read more.

We report the successful synthesis of monodispersed Cu₂S nanocrystals and the subsequent formation of highly ordered nanocrystal superlattices. The synthesis is performed under ambient air conditions using simple experimental setups, making the process both accessible and scalable. By systematically tuning the reaction temperature and duration, we demonstrate precise control over the nanocrystal size, which is crucial in achieving uniformity and monodispersity. Furthermore, we uncover a previously unidentified nanocrystal growth mechanism that plays a key role in producing highly monodisperse Cu₂S nanocrystals. This insight into the growth process enhances our fundamental understanding of nanocrystal formation and could be extended to the synthesis of other semiconductor nanomaterials. The self-assembly of these nanocrystals into superlattices is carefully examined using electron diffraction techniques, revealing the presence of pseudo-crystalline structures. The ordered arrangement of nanocrystals within these superlattices suggests strong interparticle interactions and opens up new possibilities to tailor their collective optical, electronic, and mechanical properties for potential applications in optoelectronics, nanomedicine, and energy storage. Full article

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

► Show Figures

Figure 1

18 pages, 1358 KiB

Open AccessEditor’s ChoiceArticle

Learning Self-Supervised Representations of Powder-Diffraction Patterns

by Shubhayu Das, Markus Vorholt, Andreas Houben and Richard Dronskowski

Crystals 2025, 15(5), 393; https://doi.org/10.3390/cryst15050393 - 23 Apr 2025

Viewed by 807

Abstract

The potential of machine learning (ML) models for predicting crystallographic symmetry information from single-phase powder X-ray diffraction (XRD) patterns is investigated. Given the scarcity of large, labeled experimental datasets, we train our models using simulated XRD patterns generated from crystallographic databases. A key [...] Read more.

The potential of machine learning (ML) models for predicting crystallographic symmetry information from single-phase powder X-ray diffraction (XRD) patterns is investigated. Given the scarcity of large, labeled experimental datasets, we train our models using simulated XRD patterns generated from crystallographic databases. A key challenge in developing reliable diffraction-based structure-solution tools lies in the limited availability of training data and the presence of natural adversarial examples, which hinder model generalization. To address these issues, we explore multiple training pipelines and testing strategies, including evaluations on experimental XRD data. We introduce a contrastive representation learning approach that significantly outperforms previous supervised learning models in terms of robustness and generalizability, demonstrating improved invariance to experimental effects. These results highlight the potential of self-supervised learning in advancing ML-driven crystallographic analysis. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

► Show Figures

Figure 1

18 pages, 7231 KiB

Open AccessEditor’s ChoiceArticle

Electron Beam Welding of Dissimilar Ti6Al4V and Al6082-T6 Alloys Using Magnetron-Sputtered Cu Interlayers

by Georgi Kotlarski, Darina Kaisheva, Maria Ormanova, Milka Atanasova, Angel Anchev, Vladimir Dunchev, Borislav Stoyanov and Stefan Valkov

Crystals 2025, 15(4), 373; https://doi.org/10.3390/cryst15040373 - 18 Apr 2025

Viewed by 426

Abstract

In the present work, the influence of a magnetron-sputtered copper interlayer on the process of electron beam welding of Ti6Al4V and Al6082-T6 plates was investigated. A sample without a filler was also prepared as a control. The microstructure, microhardness, and tensile properties of [...] Read more.

In the present work, the influence of a magnetron-sputtered copper interlayer on the process of electron beam welding of Ti6Al4V and Al6082-T6 plates was investigated. A sample without a filler was also prepared as a control. The microstructure, microhardness, and tensile properties of both samples were determined. Applying a copper interlayer resulted in the formation of an additional CuAl₂ intermetallic compound in the form of a eutectic structure along the boundary of the aluminum crystal grains. A noticeable shift in the preferred crystallographic orientation of the aluminum phase from the denser {111} family of crystallographic planes in the case of the sample prepared without a filler towards less-dense ones such as {110}, {100}, and {311} in the case of applying a copper filler was observed. This was most probably caused by the lower free surface energy of the crystals oriented towards the {111} family of crystal planes, which favored the chemical bonding between the aluminum solid solution and the CuAl₂ intermetallics. As a result of applying the copper interlayer, a noticeable increase in the microhardness of the weld seam was observed from 78 ± 2 HV0.05 to 136 ± 3 HV0.05. Applying a copper interlayer also led to an improved energy absorption capacity of the weld seam, as suggested by the increase in the UTS/YS ratio from 1.03 to 1.44. This could be explained by the smooth transition between the highly dissimilar Ti6Al4V and Al6082-T6 alloys. The UTS of the sample with the copper filler reached 208 MPa, which was about 60% of that of the base Al6082-T6 alloy. Full article

(This article belongs to the Special Issue Advanced Welding and Additive Manufacturing)

► Show Figures

Figure 1

18 pages, 7058 KiB

Open AccessEditor’s ChoiceArticle

Molecular Structure and GPR35 Receptor Docking of 1,3-Phenylene Bis-Oxalamide Derivatives

by Juan Saulo González-González, José Martín Santiago-Quintana, José Luis Madrigal-Angulo, Lina Barragán-Mendoza, Nancy E. Magaña-Vergara, Efrén V. García-Báez, Itzia Irene Padilla-Martínez and Francisco Javier Martínez-Martínez

Crystals 2025, 15(4), 371; https://doi.org/10.3390/cryst15040371 - 17 Apr 2025

Viewed by 398

Abstract

A series of three 1,3-phenylene bis-oxamides 3a–c, structurally related to the GPR35 receptor-agonist drug lodoxamide, has been synthesized by reacting the 1,3-phenylene bis-oxalamates 2a and 2b with amines. The obtained compounds were characterized by ¹H and ¹³C NMR, [...] Read more.

A series of three 1,3-phenylene bis-oxamides 3a–c, structurally related to the GPR35 receptor-agonist drug lodoxamide, has been synthesized by reacting the 1,3-phenylene bis-oxalamates 2a and 2b with amines. The obtained compounds were characterized by ¹H and ¹³C NMR, and IR spectroscopy, they showed characteristic signals for the aromatic, N―H, and C=O groups. Molecular structure was determined using single-crystal X-ray diffraction. The supramolecular architecture is driven by N―H···O=C, N―H···N, C—H···π, and O=C···O=C interactions depicting a supramolecular helix (3a) and tapes (3b–c). Intermolecular interactions were studied using Hirshfeld surface analysis, where N―H∙∙∙X (X = N, O) hydrogen bonding represents 30.2% to the surface of 3a and 17.8–18.8% to the surface of 3b–c. The most energetic interactions involve the amide N—H∙∙∙O hydrogen bonding, contributing in the −113.9 to −97.0 kJ mol⁻¹ range to the crystal energy, being more dispersive than electrostatic in nature. The molecular docking study was performed to evaluate the binding ability of 3a–c compounds to the GPR35 receptor, showing a favorable binding in a similar way to lodoxamide. Full article

(This article belongs to the Section Biomolecular Crystals)

► Show Figures

Figure 1

20 pages, 3934 KiB

Open AccessEditor’s ChoiceArticle

Microstructure and High-Temperature Compressive Properties of a Core-Shell Structure Dual-MAX-Phases-Reinforced TiAl Matrix Composite

by Shiqiu Liu and Huijun Guo

Crystals 2025, 15(4), 363; https://doi.org/10.3390/cryst15040363 - 16 Apr 2025

Viewed by 355

Abstract

As an advanced high-temperature structural material, TiAl alloy, is often used in the manufacturing of hot-end components of aviation and aerospace engines. However, it is difficult to increase the strength at high temperature, which limits its wider application. Adopting composite material technology is [...] Read more.

As an advanced high-temperature structural material, TiAl alloy, is often used in the manufacturing of hot-end components of aviation and aerospace engines. However, it is difficult to increase the strength at high temperature, which limits its wider application. Adopting composite material technology is one of the effective ways to improve the comprehensive mechanical properties of TiAl alloy. In this work, by adding 3 wt.% SiC micro-particles to Ti-47.5Al-7Nb-0.4W-0.1B (at.%) pre-alloyed powder, a core-shell structure dual-MAX-phase high-temperature strengthened TiAl matrix composite (also known as TiAl-SiC composite) was prepared by combining powder metallurgy and hot forging. The microstructure and high-temperature compressive properties of the prepared TiAl-SiC composites were studied and compared with TiAl alloy prepared by the same process, and the microstructural characteristics of the TiAl-SiC composite and its microstructure evolution during processing were revealed. The results show that the matrix of as-sintered TiAl-SiC composites was mainly composed of γ phase and a small amount of Ti₂AlC particles, while the reinforcement phase was a dual-MAX-phase core-shell structure, which was mainly composed of core Ti₂AlC phase, shell Ti₃SiC₂ phase, and small Ti₂AlC particles distributed in the outer layer. After hot forging, the microstructure of TiAl-SiC composite became more compact, finer, and more uniform; the phase composition was almost not changed, but the content of Ti₂AlC, Ti₃SiC₂, and TiB₂ phases increased significantly; the content of C in each constituent phase decreased obviously, and a granular Si-rich phase was generated in the core of the reinforcement phase. The yield strength of the as-forged TiAl-SiC composite was significantly higher than that of the as-forged TiAl alloy at temperature higher than 859 °C. This is because the core-shell structure dual MAX phases can effectively reduce the softening rate of TiAl alloy in the range of 800–900 °C, thus playing a strengthening role and increasing the service temperature of TiAl alloy. Full article

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

► Show Figures

Figure 1

21 pages, 13359 KiB

Open AccessEditor’s ChoiceArticle

A Novel Zinc-Based MOF Featuring 2,4,6-Tris-(4-carboxyphenoxy)-1,3,5-triazine: Structure, Adsorption, and Photocatalytic Activity

by Magdalena Angelova, Hristina Lazarova, Vanya Kurteva, Rositsa Nikolova, Rusi Rusew and Boris Shivachev

Crystals 2025, 15(4), 348; https://doi.org/10.3390/cryst15040348 - 8 Apr 2025

Viewed by 505

Abstract

A metal–organic framework, MOF-S1, was synthesized via a solvothermal reaction between 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine (TCPT) and zinc nitrate hexahydrate. Single-crystal and powder X-ray diffraction analyses confirmed the formation of hexagonal rod-shaped crystals with a trigonal (P-31c) structure featuring a two-fold interpenetrated 3D framework. [...] Read more.

A metal–organic framework, MOF-S1, was synthesized via a solvothermal reaction between 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine (TCPT) and zinc nitrate hexahydrate. Single-crystal and powder X-ray diffraction analyses confirmed the formation of hexagonal rod-shaped crystals with a trigonal (P-31c) structure featuring a two-fold interpenetrated 3D framework. A comprehensive characterization—including NMR spectroscopy, thermogravimetric analysis, and surface area measurements (using Langmuir, t-plot, Horváth–Kawazoe, and Dubinin–Radushkevich models)—revealed an ultramicroporous material with a Langmuir surface area of 711 m²/g and a median pore width of ~6.5 Å. Adsorption studies using Congo Red, Methylene Blue, Methyl Orange, and Rhodamine B demonstrated the rapid uptake and effective removal from aqueous solutions, with kinetic modeling indicating a dominant chemisorption mechanism. Photocatalytic tests under UV irradiation yielded degradation efficiencies of ~93% for Methyl Orange and ~74% for Rhodamine B. These findings suggest that MOF-S1 is a promising candidate for wastewater treatment applications and UV-related processes, offering a strong adsorption capacity and thermal stability. Full article

(This article belongs to the Special Issue Feature Papers on “Hybrid and Composite Crystalline Materials” 2025)

► Show Figures

Figure 1

34 pages, 10030 KiB

Open AccessEditor’s ChoiceArticle

Seven New Irbesartan Salts: Significantly Improved Dissolution, Excellent Hygrothermal Stability, and Characteristic Supramolecular Synthons

by Junxiao Wang, Chuanhua Wu, Menglong Zhang, Lingli Hou, Wei Chen, Dingding Jing and Ying Bao

Crystals 2025, 15(4), 342; https://doi.org/10.3390/cryst15040342 - 4 Apr 2025

Viewed by 371

Abstract

Irbesartan (IRB) is a commonly used BCS Class II antihypertensive drug requiring dissolving capacity enhancement to address oral bioavailability limitations. In this work, seven new IRB salts were successfully synthesized, including one carboxylate (IRB-MAL) and six sulfonate salts (IRB-TOSA, IRB-BSA, IRB-4-CBSA, IRB-2, 5-CBSA, [...] Read more.

Irbesartan (IRB) is a commonly used BCS Class II antihypertensive drug requiring dissolving capacity enhancement to address oral bioavailability limitations. In this work, seven new IRB salts were successfully synthesized, including one carboxylate (IRB-MAL) and six sulfonate salts (IRB-TOSA, IRB-BSA, IRB-4-CBSA, IRB-2, 5-CBSA, IRB-MSA, and IRB-CPSA). Their vitro dissolution, intrinsic dissolution rates (IDRs), thermal/hygroscopic stability (via thermal analysis, dynamic vapor sorption, and accelerated stability tests), and phase transition process (monitored by in situ Raman spectroscopy) were evaluated. The results revealed that IRB-TOSA, IRB-MAL, IRB-BSA, IRB-4-CBSA, and IRB-MSA salts exhibited IDRs of 0.3194–0.7383 mg/(cm²·min), all significantly higher than IRB, with dissolution concentrations increased by 14.9–113.6%. IRB-TOSA and IRB-4-CBSA salts demonstrated excellent hydrothermal stability. Single crystal structure analysis confirmed proton transfer from coformers’ sulfonic/carboxylic acids (deprotonation site, H-out) to IRB’s diazaheterocycles (protonation site, H-in) in IRB salts. Six sulfonate salts exhibited N_H-in–H···O_H-out and N_non-H-in–H···O_H-out hydrogen bonds, with the former absent in IRB-MAL. Furthermore, supramolecular synthon studies revealed distinct hydrogen-bonding patterns (e.g., bifurcated bonds in 2,5-CBSA and CPSA salts) that correlate with moisture resistance. Quantitative analysis of IRB salts suggested hydrogen bond strengths may influence their melting points (decomposition temperatures). This study demonstrates that IRB salts hold promise for advanced pharmaceutical applications. Full article

(This article belongs to the Section Crystal Engineering)

► Show Figures

Graphical abstract

12 pages, 7852 KiB

Open AccessEditor’s ChoiceArticle

Remineralization Effects of Zinc-Containing Glass Ionomer Cement Restoratives on Demineralized Enamel Under pH Cycling Conditions

by Khin Myanmar, Go Inoue, Xuefei Chen and Yasushi Shimada

Crystals 2025, 15(4), 329; https://doi.org/10.3390/cryst15040329 - 29 Mar 2025

Viewed by 461

Abstract

(1) Background: White spot lesions (WSLs) on enamel result from demineralization and are an early sign of dental caries. Glass ionomer cement (GIC) has been widely used for its remineralization potential, and zinc-containing GIC (zGIC) has been introduced to enhance this effect. However, [...] Read more.

(1) Background: White spot lesions (WSLs) on enamel result from demineralization and are an early sign of dental caries. Glass ionomer cement (GIC) has been widely used for its remineralization potential, and zinc-containing GIC (zGIC) has been introduced to enhance this effect. However, its efficacy compared to conventional GIC (cGIC) remains unclear. This study aimed to evaluate and compare the remineralization effects of cGIC and zGIC on WSLs. (2) Methods: Thirty-six bovine enamel specimens were prepared, demineralized for four days, and divided into three groups: control, cGIC, and zGIC. Half of each specimen’s treated window was covered with varnish, and a two-week pH cycling protocol was conducted. Mineral density (MD) changes were assessed using microcomputed tomography (Micro-CT) at five time points: pre-demineralization, after demineralization, immediately after treatment, and 1- and 2-weeks post-treatment. Scanning electron microscopy (SEM) was also performed. (3) Results: MD values in the zGIC and cGIC groups were significantly higher than in the control group throughout every post-treatment assessment (p < 0.05). zGIC demonstrated significantly higher MD than cGIC (p < 0.05), and SEM images revealed inferior mineral deposition. (4) Conclusions: These findings suggest that zGIC is more effective in remineralizing WSLs than cGIC over two weeks. Full article

(This article belongs to the Special Issue Bioinspired Mineralization of Dental Tissues)

► Show Figures

Figure 1

13 pages, 4136 KiB

Open AccessEditor’s ChoiceArticle

Biphasic WO₃ Nanostructures via Controlled Crystallization: Achieving High-Performance Electrochromism Through Amorphous/Crystalline Heterointerface Design

by Xuefeng Chu, Kunjie Lin, Haiyang Zhao, Zonghui Yao, Yaodan Chi, Chao Wang and Xiaotian Yang

Crystals 2025, 15(4), 324; https://doi.org/10.3390/cryst15040324 - 28 Mar 2025

Viewed by 400

Abstract

WO₃ electrochromic films have emerged as potential candidates for smart windows due to their cost-effectiveness, fast switching speed, and strong chemical stability. However, the inherent contradiction between the high coloring efficiency of amorphous WO₃ and the cycling durability of crystalline WO [...] Read more.

WO₃ electrochromic films have emerged as potential candidates for smart windows due to their cost-effectiveness, fast switching speed, and strong chemical stability. However, the inherent contradiction between the high coloring efficiency of amorphous WO₃ and the cycling durability of crystalline WO₃ remains a critical challenge in practical applications. This study proposes an innovative heterostructure engineering strategy, achieving precise control of the amorphous/crystalline bilayer WO₃ heterointerface (148 nm a-WO₃/115 nm c-WO₃) for the first time through phase boundary regulation, using well-controlled magnetron sputtering and post-deposition thermal annealing processes. Multimodal characterization using XRD, XPS, and SEM indicates that the heterointerface optimizes performance through a dynamic charge transfer mechanism and structural synergistic effects: the optimized bilayer structure achieves 76.57% optical modulation (at 630 nm) under −1.0 V and maintains a ΔT retention rate of 45.02% after 600 cycles, significantly outperforming single amorphous (8.34%) and crystalline films (14.34%). XPS analysis reveals a dynamic equilibrium mechanism involving W⁵⁺/Li⁺ at the interface, and the Li⁺ diffusion coefficient (D₀ = 4.29 × 10⁻¹⁰ cm²/s) confirms that the amorphous layer dominates rapid ion transport, while the crystalline matrix enhances structural stability through its ordered crystalline structure. This study offers a new paradigm for balancing the efficiency and longevity of electrochromic devices, with the compatibility of magnetic sputtering promoting the industrialization process of large-area smart windows. Full article

► Show Figures

Figure 1

13 pages, 2095 KiB

Open AccessEditor’s ChoiceArticle

Two-Dimensional Silver Bismuth Oxide/Bismuth Molybdate Z-Scheme Heterojunctions with Rich Oxygen Vacancies for Improved Pollutant Degradation and Bacterial Inactivation

by Yanhong Wang, Huijie Zhu, Pengli He, Mingyu Li, Yinhuan Cao, Yanqiang Du, Yun Wen, Yixiang Zhao, Xiaowen Liu and Yonglong Song

Crystals 2025, 15(4), 318; https://doi.org/10.3390/cryst15040318 - 27 Mar 2025

Viewed by 267

Abstract

The effective removal of organic pollutants and bacteria are of great significance considering the hazards to the environment and human health. The two-dimensional AgBiO₃/Bi₂MoO₆ heterojunction with rich oxygen vacancies was successfully fabricated via a hydrothermal method and systematically [...] Read more.

The effective removal of organic pollutants and bacteria are of great significance considering the hazards to the environment and human health. The two-dimensional AgBiO₃/Bi₂MoO₆ heterojunction with rich oxygen vacancies was successfully fabricated via a hydrothermal method and systematically characterized by various analytical techniques. The photocatalytic experimental results revealed that the addition of AgBiO₃ improved the photocatalytic performance of Bi₂MoO₆, and the AgBiO₃/Bi₂MoO₆-10 heterojunction possessed the best degradation effect toward RhB (72%) within 100 min, with 1.38 and 1.44 times higher activity than pure Bi₂MoO₆ and AgBiO₃, respectively. The bacteria were completely inactivated within 90 min by AgBiO₃/Bi₂MoO₆-10 heterojunction. The reason for the enhancement of photocatalytic activity was the synergistic effect between AgBiO₃ and Bi₂MoO₆. The constructed Z-scheme heterojunction with oxygen vacancies improved the separation efficiency of photo-induced electrons and holes and broadened the range of visible-light absorption. The trapping experiments and ESR indicated that superoxide radical and holes were the main reactive species. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

► Show Figures

Figure 1

8 pages, 1936 KiB

Open AccessEditor’s ChoiceArticle

Thermally Induced Ion Magnetic Moment in H₄O Superionic State

by Xiao Liang, Junhao Peng, Fugen Wu, Renhai Wang, Yujue Yang, Xingyun Li and Huafeng Dong

Crystals 2025, 15(4), 304; https://doi.org/10.3390/cryst15040304 - 26 Mar 2025

Viewed by 337

Abstract

The hydrogen ions in superionic ice can move freely, playing the role of electrons in metals. Its electromagnetic behavior is the key to explaining the anomalous magnetic fields of Uranus and Neptune. Based on an ab initio evolutionary algorithm, we searched for the [...] Read more.

The hydrogen ions in superionic ice can move freely, playing the role of electrons in metals. Its electromagnetic behavior is the key to explaining the anomalous magnetic fields of Uranus and Neptune. Based on an ab initio evolutionary algorithm, we searched for the stable H₄O crystal structure under pressures of 500–5000 GPa and discovered a new layered-chain Pmn2₁-H₄O structure with H₃ ion clusters. Interestingly, H₃ ion clusters rotate above 900 K (with an instantaneous speed of 3000 m/s at 900 K), generating an instantaneous magnetic moment (~10⁻²⁶ A·m² ≈ 0.001

μ_{B}

). Moreover, H ions diffuse in a direction perpendicular to the H-O atomic layer at 960–1000 K. This is because the hydrogen–oxygen covalent bonds within the hydrogen–oxygen plane hinder the diffusion behavior of H₃ ion clusters within the plane, resulting in the diffusion of H₃ ion clusters between the hydrogen–oxygen planes and the formation of a one-dimensional conductive superionic state. One-dimensional diffusion of ions may generate magnetic fields. We refer to these two types of magnetic moments as “thermally induced ion magnetic moments”. When the temperature exceeds 1000 K, H ions diffuse in three directions. When the temperature exceeds 6900 K, oxygen atoms diffuse and the system becomes fluid. These findings provide important references for people to re-recognize the physical and chemical properties of hydrogen and oxygen under high pressure, as well as the sources of abnormal magnetic fields in Uranus and Neptune. Full article

► Show Figures

Figure 1

14 pages, 12903 KiB

Open AccessEditor’s ChoiceArticle

Biochemical and Structural Characterization of Glyoxylate Reductase/Hydroxypyruvate Reductase from Bacillus subtilis

by Thang Quyet Nguyen, Thai Huu Duong, Jin Kuk Yang and Wonchull Kang

Crystals 2025, 15(4), 298; https://doi.org/10.3390/cryst15040298 - 25 Mar 2025

Viewed by 440

Abstract

D-2-hydroxyacid dehydrogenases (2HADHs) catalyze the reversible reaction of 2-ketocarboxylic acid to the corresponding (R)-2-hydroxycarboxylic acids using NAD(P)H cofactor. As the preference of the cofactor and substrate varies among homologs, biochemical characterization is required to understand this enzyme. Here, we analyzed the biochemical properties [...] Read more.

D-2-hydroxyacid dehydrogenases (2HADHs) catalyze the reversible reaction of 2-ketocarboxylic acid to the corresponding (R)-2-hydroxycarboxylic acids using NAD(P)H cofactor. As the preference of the cofactor and substrate varies among homologs, biochemical characterization is required to understand this enzyme. Here, we analyzed the biochemical properties of Bacillus subtilis glyoxylate reductase/hydroxypyruvate reductase (BsGRHPR), which catalyzes the reduction of both glyoxylate (EC 1.1.1.26) and hydroxypyruvate (EC 1.1.1.81). Enzyme kinetics showed a preference for hydroxypyruvate over glyoxylate, with a seven-fold higher specificity constant. In addition, BsGRHPR displayed a strict preference for NADPH over NADH as a cofactor. The crystal structures of BsGRHPR in complex with formate were determined in the presence and absence of the cofactor at near-atomic resolution. Structural comparisons revealed conformational changes upon cofactor binding and key residues, such as Asp80, R157, R179, R239, Asp263, and Arg296. In addition, substrate-binding analysis highlighted conserved residues, including Val77, Gly78, His287, and S290. Our structures suggest that Glu137, His287, Ser290, and Arg296 serve as gatekeepers at the entrance of the tunnel. This comprehensive characterization of BsGRHPR elucidates its substrate specificity, cofactor preference, and catalytic mechanism, contributing to a broader understanding of GRHPR family enzymes, with potential implications for metabolic engineering applications. Full article

(This article belongs to the Special Issue Crystallography of Enzymes)

► Show Figures

Figure 1

13 pages, 3390 KiB

Open AccessEditor’s ChoiceArticle

Mössbauer and Optical Investigations on Sr Doped M-Type BaFe₁₂O₁₉ Hexaferrites Produced via Autocombustion

by Benilde F. O. Costa, Adel Benali, Bruno J. C. Vieira, João C. Waerenborgh, João Pina, Yousra Marouani and Essebti Dhahri

Crystals 2025, 15(4), 291; https://doi.org/10.3390/cryst15040291 - 24 Mar 2025

Viewed by 438

Abstract

Ba_1−xSr_xFe₁₂O₁₉ (x = 0.0, 0.5 and 1.0) hard-magnetic nanohexaferrites prepared by autocombustion were primarily investigated using Mössbauer spectroscopy and optical studies. Morphological examination by electron scanning microscopy revealed that the particles agglomerated into grains with a [...] Read more.

Ba_1−xSr_xFe₁₂O₁₉ (x = 0.0, 0.5 and 1.0) hard-magnetic nanohexaferrites prepared by autocombustion were primarily investigated using Mössbauer spectroscopy and optical studies. Morphological examination by electron scanning microscopy revealed that the particles agglomerated into grains with a hexagonal shape. The grain size increases with the amount of Sr content, from ca. 490 nm (x = 0.0) to ca. 700 nm (x = 1.0). Room-temperature Mössbauer spectroscopy showed that the mean hyperfine field increased with the substitution of Ba²⁺ by Sr²⁺, consistent with magnetization results. The preferential sites occupied by Fe ions in the hexaferrite structure were determined. Optical studies revealed that all compounds absorb up to ca. 1000 nm, and that the bandgap energy decreases with increasing Sr content. Full article

(This article belongs to the Special Issue Metal Oxides: Crystal Structure, Synthesis and Characterization (2nd Edition))

► Show Figures

Figure 1

20 pages, 4199 KiB

Open AccessEditor’s ChoiceArticle

The Stirring Effect on the Crystal Morphology of p-Acetamidobenzoic Acid Solution Crystallization

by Rui Dong, Fan Wang, Dingding Jing, Yong Liu and Ying Bao

Crystals 2025, 15(3), 284; https://doi.org/10.3390/cryst15030284 - 20 Mar 2025

Viewed by 624

Abstract

This work investigates the stirring effect on p-Acetamidobenzoic Acid (p -AABA) crystal morphology through single crystal cultivation, crystal face growth rate, and nucleation supersaturation measurements, molecular simulation (MS), and computational fluid dynamics (CFD). Results show that stirring rate influences nucleation supersaturation, [...] Read more.

This work investigates the stirring effect on p-Acetamidobenzoic Acid (p -AABA) crystal morphology through single crystal cultivation, crystal face growth rate, and nucleation supersaturation measurements, molecular simulation (MS), and computational fluid dynamics (CFD). Results show that stirring rate influences nucleation supersaturation, boundary layer thickness on the {101} and {010} faces, and shear stress applied on these two faces. This leads to changes in nucleation rate, nucleus size, and relative growth rates between the {101} and {010} faces, thus affecting crystal morphology. Under low-rate stirring (150 rpm), crystals exhibit a small size, a low aspect ratio, and a clear aggregation phenomenon. Appropriately increasing stirring rate can prevent aggregation and improve particle size and crystal aspect ratio. High-rate stirring leads to a higher shear stress at the corner points of the {101} face, causing crystal fragmentation, which leads to a significant decrease in crystal size and a slow decrease in aspect ratio. Moreover, the growth rates of the {101} and {010} faces exhibit an exponential dependence on supersaturation. The {101} face grows faster than the {010} face, and this growth rate difference widens with the increasing supersaturation. This study provides a theoretical basis and practical guidance for optimizing crystal morphology in stirred solution crystallization. Full article

(This article belongs to the Section Crystal Engineering)

► Show Figures

Figure 1

26 pages, 6566 KiB

Open AccessEditor’s ChoiceReview

The B30.2/SPRY-Domain: A Versatile Binding Scaffold in Supramolecular Assemblies of Eukaryotes

by Peer R. E. Mittl and Hans-Dietmar Beer

Crystals 2025, 15(3), 281; https://doi.org/10.3390/cryst15030281 - 19 Mar 2025

Viewed by 714

Abstract

B30.2 domains, sometimes referred to as PRY/SPRY domains, were originally identified by sequence profiling methods at the gene level. The B30.2 domain comprises a concanavalin A-like fold consisting of two twisted seven-stranded anti-parallel β-sheets. B30.2 domains are present in about 150 human and [...] Read more.

B30.2 domains, sometimes referred to as PRY/SPRY domains, were originally identified by sequence profiling methods at the gene level. The B30.2 domain comprises a concanavalin A-like fold consisting of two twisted seven-stranded anti-parallel β-sheets. B30.2 domains are present in about 150 human and 700 eukaryotic proteins, usually fused to other domains. The B30.2 domain represents a scaffold, which, through six variable loops, binds different unrelated peptides or endogenous low-molecular-weight compounds. At the cellular level, B30.2 proteins engage in supramolecular assemblies with important signaling functions. In humans, B30.2 domains are often found in E3-ligases, such as tripartite motif (Trim) proteins, SPRY domain-containing SOCS box proteins, Ran binding protein 9 and −10, Ret-finger protein-like, and Ring-finger proteins. The B30.2 protein recognizes the target and recruits the E2-conjugase by means of the fused domains, often involving specific adaptor proteins. Further well-studied B30.2 proteins are the methyltransferase adaptor protein Ash2L, some butyrophilins, and Ryanodine Receptors. Although the affinity of an isolated B30.2 domain to its ligand might be weak, it can increase strongly due to avidity effects upon recognition of oligomeric targets or in the context of macromolecular machines. Full article

(This article belongs to the Special Issue Protein Crystallography: The State of the Art)

► Show Figures

Graphical abstract

18 pages, 15306 KiB

Open AccessEditor’s ChoiceReview

Emission Wavelength Control via Molecular Structure Design of Dinuclear Pt(II) Complexes: Optimizing Optical Properties for Red- and Near-Infrared Emissions

by Hea Jung Park

Crystals 2025, 15(3), 273; https://doi.org/10.3390/cryst15030273 - 15 Mar 2025

Viewed by 701

Abstract

Phosphorescent Pt(II) complexes have garnered significant attention as key components in luminescence-based systems due to their highly efficient emission properties. A notable characteristic of these complexes is their ability to form excimers through strong molecular stacking in concentrated solutions or solid film states. [...] Read more.

Phosphorescent Pt(II) complexes have garnered significant attention as key components in luminescence-based systems due to their highly efficient emission properties. A notable characteristic of these complexes is their ability to form excimers through strong molecular stacking in concentrated solutions or solid film states. This aggregation-driven emission, primarily arising from metal–metal to ligand charge transfer (MMLCT), is influenced by overlapping d-orbitals oriented perpendicular to the square planar structure of the Pt(II) complexes. Although this property hinders the development of pure blue-emitting Pt(II) complexes, it facilitates the design of materials that emit red- and near-infrared (NIR) light. By employing advanced molecular design techniques, dinuclear Pt(II) complexes have been optimized to significantly enhance red and NIR emissions through the modulation of Pt-Pt interactions and adjustments in ligand electron densities. This review elucidates how the control of Pt-Pt distances and strategic ligand modifications can directly influence the emission spectra toward red and NIR regions. A comparative analysis of recent studies underscores the novelty and effectiveness of double-decker-type dinuclear Pt(II) complexes in achieving efficient emission characteristics in the long-wavelength range. These insights may guide the design of molecular structures for next-generation organometallic phosphorescent materials. Full article

(This article belongs to the Special Issue Feature Papers on “Hybrid and Composite Crystalline Materials” 2025)

► Show Figures

Figure 1

17 pages, 4834 KiB

Open AccessEditor’s ChoiceReview

Advancements in the Research on the Preparation and Growth Mechanisms of Various Polymorphs of Calcium Carbonate: A Comprehensive Review

by Cheng-Gong Lu, Chu-Jie Jiao, Xiu-Cheng Zhang, Jian-Sheng Zheng and Xue-Fei Chen

Crystals 2025, 15(3), 265; https://doi.org/10.3390/cryst15030265 - 13 Mar 2025

Viewed by 944

Abstract

Calcium Carbonate (CC) exhibits broad application prospects and significant market demand due to its diverse polymorphs, each with distinct potential for application in various fields. Consequently, the preparation of CC with specific polymorphs has emerged as a research hotspot. This paper commences with [...] Read more.

Calcium Carbonate (CC) exhibits broad application prospects and significant market demand due to its diverse polymorphs, each with distinct potential for application in various fields. Consequently, the preparation of CC with specific polymorphs has emerged as a research hotspot. This paper commences with an overview of the structure of CC, followed by an analysis of the advantages and disadvantages, as well as the mechanisms, of common preparation methods such as physical methods, chemical carbonation processes, and double displacement reactions. Special emphasis is placed on elucidating the influence of polymorph control agents (including inorganic ions, sugars, alcohols, and acids), process conditions (temperature, stirring rate, pH, and solution mixing rate), and reactor configurations (rotating packed beds and high-gravity reactors) on the polymorph regulation of CC. This paper points out how these factors alter the crystal formation process. Furthermore, it introduces the nucleation and growth control of CC crystallization, analyzing the mechanisms underlying these two processes. Research indicates that the carbonation process is currently a relatively mature preparation technique, with multiple factors synergistically influencing the polymorph and particle size of CC. Future efforts should focus on further improving production processes, exploring novel polymorph control agents, and delving deeper into the intrinsic mechanisms of polymorph control to achieve efficient preparation of diverse CC types. Full article

(This article belongs to the Special Issue Crystalline Materials: Polymorphism)

► Show Figures

Figure 1

11 pages, 4438 KiB

Open AccessEditor’s ChoiceArticle

Effects of Zr Alloying on Microstructure Evolution and Mechanical Properties of CoCrNi Medium Entropy Alloy

by Ao Li, Zurong Gong, Dong Li, Xiaohong Wang, Yunting Su, Tengfei Ma, Bin Liu and Baochen Zhang

Crystals 2025, 15(3), 258; https://doi.org/10.3390/cryst15030258 - 10 Mar 2025

Viewed by 563

Abstract

Alloying provides an effective approach to designing metallic materials with unique microstructures and enhanced performance. In this work, we developed a series of (CoCrNi)_100−xZr_x (where x = 1, 2, 3, 4, and 5) medium entropy alloys (MEAs) by vacuum arc-melting [...] Read more.

Alloying provides an effective approach to designing metallic materials with unique microstructures and enhanced performance. In this work, we developed a series of (CoCrNi)_100−xZr_x (where x = 1, 2, 3, 4, and 5) medium entropy alloys (MEAs) by vacuum arc-melting method. The effects of Zr addition on the microstructures and mechanical properties of (CoCrNi)_100−xZr_x MEAs were systematically investigated. Due to the negative mixing enthalpy of Zr with Co, Cr, and Ni, lamellar C15 Laves-phase precipitates formed within the ductile FCC matrix. As the Zr content increases, the alloys exhibit higher strength but become more brittle at room temperature. Among the (CoCrNi)_100−xZr_x MEAs series, the CoCrNiZr₃ MEA shows an excellent balance between strength and ductility, achieving a compressive yield strength of 610 MPa and a hardness of 249 HV, respectively, while maintaining a good ductility beyond 45%. Microstructural analysis using scanning electron microscope and transmission electron microscope suggests that this outstanding strength-ductility balance of CoCrNiZr₃ MEA arises from the synergistic effect of precipitation strengthening and solid solution strengthening. These findings not only provide deeper insight into the interaction between different strengthening mechanisms but also offer valuable guidance for designing high-performance multi-component alloys through strategic alloying. Full article

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

► Show Figures

Figure 1

16 pages, 986 KiB

Open AccessEditor’s ChoiceArticle

Formation of Ice I_h Clusters in Solid-Phase Glacial Water with Low Concentrations of Ca²⁺ and Mg²⁺ Ions

by Ignat Ignatov, Yordan G. Marinov, Paunka Vassileva, Teodora P. Popova, Georgi Gluhchev, Mario T. Iliev, Fabio Huether, Zhechko Dimitrov and Irina Gotova

Crystals 2025, 15(3), 254; https://doi.org/10.3390/cryst15030254 - 9 Mar 2025

Cited by 2 | Viewed by 803

Abstract

This study explores the structural and chemical interactions between glacial water, ice I_h, and hydration clusters of divalent cations (Ca²⁺ and Mg²⁺). Ice I_h, with its hexagonal lattice and tetrahedral bonding network, is incompatible with [...] Read more.

This study explores the structural and chemical interactions between glacial water, ice I_h, and hydration clusters of divalent cations (Ca²⁺ and Mg²⁺). Ice I_h, with its hexagonal lattice and tetrahedral bonding network, is incompatible with the hydration shells of Ca²⁺ and Mg²⁺, which adopt octahedral geometries in aqueous solutions. During freezing, these hydration clusters become disordered, causing distortions in the ice structure. Slow freezing reduces these distortions, while rapid freezing traps ions in amorphous regions, preventing proper alignment of hydration clusters. Through advanced techniques such as chemical and isotopic analysis, computational modeling, and electrical impedance spectroscopy, this study examines ion exclusion mechanisms and water-clustering behaviors. The results show that both ions are largely excluded from the solid phase during freezing, with Mg²⁺ exhibiting stronger exclusion due to its smaller ionic radius and greater hydration energy. This study also highlights the role of sediments in modulating ion patterns in glacial ice. This work deepens our understanding of ion–ice interactions, offering insights for cryochemistry, hydrology, and environmental science. The integration of experimental and computational methods provides new perspectives on divalent cations’ role in modifying ice’s crystalline structure and explains isotopic variability in glacial waters. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Editor’s Choice Articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI