Crystals

24 pages, 3749 KiB

Open AccessArticle

Complex Coacervates: From Polyelectrolyte Solutions to Multifunctional Hydrogels for Bioinspired Crystallization

by Dominik Gruber, Cristina Ruiz-Agudo, Ashit Rao, Simon Pasler, Helmut Cölfen and Elena V. Sturm

Crystals 2024, 14(11), 959; https://doi.org/10.3390/cryst14110959 (registering DOI) - 2 Nov 2024

Abstract

Hydrogels represent multifarious functional materials due to their diverse ranges of applicability and physicochemical properties. The complex coacervation of polyacrylate and calcium ions or polyamines with phosphates has been uncovered to be a fascinating approach to synthesizing of multifunctional physically crosslinked hydrogels. To [...] Read more.

Hydrogels represent multifarious functional materials due to their diverse ranges of applicability and physicochemical properties. The complex coacervation of polyacrylate and calcium ions or polyamines with phosphates has been uncovered to be a fascinating approach to synthesizing of multifunctional physically crosslinked hydrogels. To obtain this wide range of properties, the synthesis pathway is of great importance. For this purpose, we investigated the entire mechanism of calcium/polyacrylate, as well as phosphate/polyamine coacervation, starting from early dynamic ion complexation by the polymers, through the determination of the phase boundary and droplet formation, up to the growth and formation of thermodynamically stable macroscopic coacervate hydrogels. By varying the synthesis procedure, injectable hydrogels, as well as plastic coacervates, are presented, which cover a viscosity range of three orders of magnitude. Furthermore, the high calcium content of the calcium/polyacrylate coacervate (~19 wt.%) enables the usage of those coacervates as an ions reservoir for the formation of amorphous and crystalline calcium-containing salts like calcium carbonates and calcium phosphates. The exceptional properties of the coacervates obtained here, such as thermodynamic stability, viscosity/plasticity, resistance to acids, and adhesive strength, combined with the straightforward synthesis and the character of an ions reservoir, open a promising field of bioinspired composite materials for osteology and dentistry. Full article

(This article belongs to the Collection Topic Collection: Mineralogical Crystallography)

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4 pages, 140 KiB

Open AccessEditorial

Progress in the Applications of Photovoltaic Functional Crystals and Ceramics

by Linghang Wang and Gang Xu

Crystals 2024, 14(11), 958; https://doi.org/10.3390/cryst14110958 (registering DOI) - 1 Nov 2024

Abstract

With the progression of mankind and the development of technology, great strides have been made regarding the application of inorganic crystalline materials in a number of fields such as high-energy and nuclear physics, environmental and safety inspection, the optoelectronics and communication fields, energy, [...] Read more.

With the progression of mankind and the development of technology, great strides have been made regarding the application of inorganic crystalline materials in a number of fields such as high-energy and nuclear physics, environmental and safety inspection, the optoelectronics and communication fields, energy, and aerospace engineering, particularly the industrialization of photovoltaic and detector materials, which has brought mankind’s knowledge of natural disciplines to an all-time high [...] Full article

(This article belongs to the Special Issue Photovoltaic Functional Crystals and Ceramics)

25 pages, 7939 KiB

Open AccessArticle

Design and Application of a Lightweight Plate-Type Acoustic Metamaterial for Vehicle Interior Low-Frequency Noise Reduction

by Yudong Wu, Wang Yan, Guang Wen, Yanyong He, Shiqi Deng and Weiping Ding

Crystals 2024, 14(11), 957; https://doi.org/10.3390/cryst14110957 (registering DOI) - 31 Oct 2024

Abstract

To reduce the low-frequency noise inside automobiles, a lightweight plate-type locally resonant acoustic metamaterial (LRAM) is proposed. The design method for the low-frequency bending wave bandgap of the LRAM panel was derived. Prototype LRAM panels were fabricated and tested, and the effectiveness of [...] Read more.

To reduce the low-frequency noise inside automobiles, a lightweight plate-type locally resonant acoustic metamaterial (LRAM) is proposed. The design method for the low-frequency bending wave bandgap of the LRAM panel was derived. Prototype LRAM panels were fabricated and tested, and the effectiveness of the bandgap design was verified by measuring the vibration transmission characteristics of the steel panels with the installed LRAM. Based on the bandgap design method, the influence of geometric and material parameters on the bandgap of the LRAM panel was investigated. The LRAM panel was installed on the inner side of the tailgate of a traditional SUV, which effectively reduced the low-frequency noise (around 34 Hz) during acceleration and constant-speed driving, improving the subjective perception of the low-frequency noise from “very unsatisfactory” to “basically satisfactory”. Furthermore, the noise reduction performance of the LRAM panel was compared with that of traditional damping panels. It was found that, with a similar installation area and lighter weight than the traditional damping panels, the LRAM panel still achieved significantly better low-frequency noise reduction, exhibiting the advantages of lightweight, superior low-frequency performance, designable bandgap and shape, and high environmental reliability, which suggests its great potential for low-frequency noise reduction in vehicles. Full article

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

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18 pages, 5372 KiB

Open AccessArticle

Influence of Ionic Liquids on the Functionality of Optoelectronic Devices Employing CsPbBr₃ Single Crystals

by Faisal Alresheedi

Crystals 2024, 14(11), 956; https://doi.org/10.3390/cryst14110956 (registering DOI) - 31 Oct 2024

Abstract

Regulating the nucleation temperature and growth rates during inverse temperature crystallization (ITC) is vital for obtaining high-quality perovskite single crystals via this technique. Precise control over these parameters enables growing crystals optimized for various optoelectronic devices. In this study, it is demonstrated that [...] Read more.

Regulating the nucleation temperature and growth rates during inverse temperature crystallization (ITC) is vital for obtaining high-quality perovskite single crystals via this technique. Precise control over these parameters enables growing crystals optimized for various optoelectronic devices. In this study, it is demonstrated that incorporating a 1-butyl-3-methylimidazolium bromide (BMIB) ionic liquid into the precursor solution of cesium lead bromide (CsPbBr₃) brings about a dual enhancement effect. This includes a reduction in nucleation temperature from 85 °C to 65 °C and a significant improvement in both optoelectronic characteristics and crystal properties. The CsPbBr₃ single crystals grown using ITC with BMIB added (method (2)) demonstrate improved chemical and physical properties (crystallinity, lattice strain, nonradioactive recombination, and trap density) compared to CsPbBr₃ single crystals produced through conventional 85 °C ITC alone (method (1)). The exceptional quality of CsPbBr₃ single crystals produced with the inclusion of BMIB allowed for the development of a highly responsive optoelectronic device, demonstrating heightened sensitivity to green light. The findings of this investigation reveal that the growth of perovskite single crystals assisted by ionic liquid exerts a substantial impact on the characteristics of the crystals. This influence proves advantageous for the development of optoelectronic devices based on single crystals. Full article

(This article belongs to the Special Issue Crystal Structures and Applications of Perovskite Halides in Solar Cells)

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13 pages, 5853 KiB

Open AccessArticle

Crystallographic Orientation of Grains Formed in the Laser Melt-Pool of (CoCuFeZr)₁₇Sm₂ Anisotropic Permanent Magnets

by Felix Trauter, Ralf Loeffler, Gerhard Schneider and Dagmar Goll

Crystals 2024, 14(11), 955; https://doi.org/10.3390/cryst14110955 (registering DOI) - 31 Oct 2024

Abstract

Textured microstructures and anisotropic properties are key factors for the optimization of magnetic materials. Only for high texture grades can the remanence J_r and the maximum energy product (BH)_max be maximized. In additive manufacturing such as laser powder bed fusion (PBF-LB), [...] Read more.

Textured microstructures and anisotropic properties are key factors for the optimization of magnetic materials. Only for high texture grades can the remanence J_r and the maximum energy product (BH)_max be maximized. In additive manufacturing such as laser powder bed fusion (PBF-LB), methods to achieve texture have to be developed. In this work, anisotropic (CoCuFeZr)₁₇Sm₂ sintered magnets have been used as a substrate in experiments featuring single laser tracks to study the relationships between crystallographic orientation of the substrate grains and crystallographic orientation of grain growth in the melt-pool. The <0001> crystal direction (c-axis) of the substrate has been systematically varied with respect to the orientation of the laser scan track on the specimen surface. Crystallographic orientations of the melt-pool and the substrate have been analyzed using electron backscatter diffraction (EBSD). It is found that if the c-axis is oriented perpendicular to the temperature gradient in the melt-pool, grains grow with orientation similar to that of the substrate grain. If the c-axis and the temperature gradient are oriented in the same direction, the grains grow with high misorientation to the substrate. The highest anisotropy in the melt-pool is achieved when the substrate’s c-axis is oriented along the laser scan track. Under these conditions, 98.7% of the melt-pool area shows a misorientation <45° compared to the substrate orientation. The texture grade of the melt-pool area is comparable to that of the substrate magnet, at 91.8% and 92.2%, respectively. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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8 pages, 783 KiB

Open AccessCommunication

Empirical Analysis of Stability of A_n+1B_nO_3n+1 Ruddlesden–Popper Phases Using Reciprocal n-Values

by Sergei Vereshchagin and Vyacheslav Dudnikov

Crystals 2024, 14(11), 954; https://doi.org/10.3390/cryst14110954 (registering DOI) - 31 Oct 2024

Abstract

Layered A_n+1B_nO_3n+1 (n = 1…∞) Ruddlesden–Popper (RP) phases are a promising system for a variety of applications. Within the RP family, the thermodynamic properties of the phases are essentially additive with variation in the n value, but [...] Read more.

Layered A_n+1B_nO_3n+1 (n = 1…∞) Ruddlesden–Popper (RP) phases are a promising system for a variety of applications. Within the RP family, the thermodynamic properties of the phases are essentially additive with variation in the n value, but at present, there are no general approaches that would allow one to evaluate the individual stability of the RP phases and the possibility of their interconversion. The aim of this paper is to present a novel concept for performing a thermodynamic analysis of RP phases using the reciprocal values of the index n. We present an empirical equation ΔG_1/n = ΔG_P + B₁/n + B₂/n², where ΔG_1/n and ΔG_P are the molar Gibbs energies of formation of the Ruddlesden–Popper (RP) phase (AO)_1/nABO₃ and the parent ABO₃ perovskite, respectively, and n is a stoichiometry index of A_n+1B_nO_3n+1 RP phase. The correlation was validated using available thermodynamic data for the systems Sr-Ti-O, Ca-Ti-O, Sr-Zr-O, La-Ni-O, and La-Co-O. For all A-B combinations, the equation quantitatively describes the Gibbs energy of RP phase formation. Predicted values for the non-linear approximation lie within the experimental uncertainty in determining ΔG_1/n. The proposed correlation was used to analyze the relative stability of the RP phases and to determine the feasibility of synthesizing new compounds. Full article

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

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19 pages, 13789 KiB

Open AccessArticle

Self-Organization of Micro- and Nanosystems in the Form of Patterns

by Vyacheslav Perekrestov, Anna Kornyushchenko, Yuliia Kosminska, Maksym Kubakh and Gerhard Wilde

Crystals 2024, 14(11), 953; https://doi.org/10.3390/cryst14110953 (registering DOI) - 31 Oct 2024

Abstract

In this work, the peculiarities of self-organization of patterned micro- and nanosystems under near-equilibrium condensation conditions were consistently considered. The criteria for stationarity of near-equilibrium condensation were introduced, and interrelations between the condensate local growth kinetics and the corresponding local technological parameters were [...] Read more.

In this work, the peculiarities of self-organization of patterned micro- and nanosystems under near-equilibrium condensation conditions were consistently considered. The criteria for stationarity of near-equilibrium condensation were introduced, and interrelations between the condensate local growth kinetics and the corresponding local technological parameters were described. Dissipative self-organization of small supersaturations in physically and chemically active medium-condensate systems were compared. The effectiveness of the unification of dissipative self-organization of small supersaturations and conservative self-organization of patterned micro- and nanosystems formation was shown, which forms the basis of a new concept of complete self-organized systems. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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10 pages, 2586 KiB

Open AccessArticle

AlGaN-Based Ultraviolet PIN Photodetector Grown on Silicon Substrates Using SiN Nitridation Process and Step-Graded Buffers

by Jian Li, Yan Maidebura, Yang Zhang, Gang Wu, Yanmei Su, Konstantin Zhuravlev and Xin Wei

Crystals 2024, 14(11), 952; https://doi.org/10.3390/cryst14110952 (registering DOI) - 31 Oct 2024

Abstract

The integration of aluminum gallium nitride (AlGaN) with silicon substrates attracts significant attention due to the superior UV sensitivity of AlGaN and the cost-effectiveness as well as mechanical robustness of silicon. A PIN ultraviolet photodetector with a peak detection wavelength of 274 nm [...] Read more.

The integration of aluminum gallium nitride (AlGaN) with silicon substrates attracts significant attention due to the superior UV sensitivity of AlGaN and the cost-effectiveness as well as mechanical robustness of silicon. A PIN ultraviolet photodetector with a peak detection wavelength of 274 nm is presented in this paper. By employing a SiN nucleation layer and a step-graded buffer, a high-quality AlGaN-based photodetector structure with a dislocation density of 2.4 × 10⁹/cm² is achieved. A double-temperature annealing technique is utilized to optimize the Ohmic contact of the n-type AlGaN. The fabricated UV photodetector attains a dark current of 0.12 nA at −1 V and a peak responsivity of 0.12 A/W. Full article

(This article belongs to the Special Issue Crystal Growth of III–V Semiconductors)

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11 pages, 4770 KiB

Open AccessArticle

Amorphous-like TiN Films as Barrier Layers for Copper

by Shicheng Han, Shicheng Yang, Xiaohong Zeng, Ying Wu, Tong Liu, Hu Wang and Sunan Ding

Crystals 2024, 14(11), 951; https://doi.org/10.3390/cryst14110951 - 31 Oct 2024

Abstract

The titanium nitride (TiN) columnar structure results in a rapid diffusion of copper atoms into the substrate along a vertical path. In this paper, the TiN columnar growth process was modified, which resulted in the deposition of amorphous-like films. The amorphous-like TiN layer [...] Read more.

The titanium nitride (TiN) columnar structure results in a rapid diffusion of copper atoms into the substrate along a vertical path. In this paper, the TiN columnar growth process was modified, which resulted in the deposition of amorphous-like films. The amorphous-like TiN layer demonstrated a low resistivity of 75.3 μΩ·cm. For the test structure of Cu/TiN/SiO₂, the Cu diffusion depth in the 3 nm TiN middle layer was only approximately 1 nm after annealing at 750 °C for 30 min. Excellent copper diffusion barrier due to high density and complex diffusion pathways. The results of this study suggest that conventional barrier materials can still be used in ultra-narrow copper interconnects. Full article

(This article belongs to the Section Crystal Engineering)

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11 pages, 3907 KiB

Open AccessArticle

The Influence of Deposition Temperature on the Microscopic Process of Diamond-like Carbon (DLC) Film Deposition on a 2024 Aluminum Alloy Surface

by Li Yang, Tong Li, Baihui Shang, Lili Guo, Tong Zhang and Weina Han

Crystals 2024, 14(11), 950; https://doi.org/10.3390/cryst14110950 - 31 Oct 2024

Abstract

In this experiment, plasma-enhanced chemical vapor deposition technology was used to deposit diamond-like carbon thin films on the surface of a 2024 aluminum alloy. The effects of deposition temperature on the microstructure, carbon, silicon, and aluminum element distribution, and film substrate adhesion of [...] Read more.

In this experiment, plasma-enhanced chemical vapor deposition technology was used to deposit diamond-like carbon thin films on the surface of a 2024 aluminum alloy. The effects of deposition temperature on the microstructure, carbon, silicon, and aluminum element distribution, and film substrate adhesion of diamond-like carbon thin films were studied using field emission scanning electron microscopy, energy-dispersive spectroscopy, XRD, scratch gauge, and ultra-depth-of-field microscopy. The results showed that with the increase in deposition temperature, the thickness of DLC film decreased from 8.72 μm to 5.37 μm, and the film bonded well with the substrate. There is a clear transition layer containing silicon elements between the DLC film and the aluminum alloy substrate. The transition layer is a solid solution formed by aluminum and silicon elements, which increases the bonding strength between the film and substrate. C-Si and C-C exist in the form of covalent bonds and undergo orbital hybridization, making the DLC film more stable. When the deposition temperature exceeds the aging temperature of a 2024 aluminum alloy, it will affect the properties of the aluminum alloy substrate. Therefore, the deposition temperature should be below the aging temperature of the 2024 aluminum alloy for coating. At a deposition temperature of 100 °C, the maximum membrane substrate bonding force is 14.45 N. When a continuous sound signal appears and the friction coefficient is the same as that of the substrate, the film is completely damaged. From the super-depth map of the scratch morphology, it can be seen that, at a deposition temperature of 100 °C, a small amount of thin film detachment appears around the scratch. Full article

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

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23 pages, 21704 KiB

Open AccessArticle

Surface Modification of Graphene Oxide and Its Strengthening and Toughening Mechanism for Alumina-Based Ceramic Materials

by Yangyang Hu, Zhenzhen Feng, Yonghui Xie, Hongyang Wang, Qinglong Ji, Jiaoni Wang and Chonghai Xu

Crystals 2024, 14(11), 949; https://doi.org/10.3390/cryst14110949 - 31 Oct 2024

Abstract

This study investigated the effects of incorporating reduced-graphene-oxide-coated alumina (Al₂O₃–RGO) nanoparticles and unmodified graphene oxide (GO) onto the microstructure as well as the mechanical properties of Al₂O₃/TiB₂ matrix ceramic materials. The microstructure observation revealed [...] Read more.

This study investigated the effects of incorporating reduced-graphene-oxide-coated alumina (Al₂O₃–RGO) nanoparticles and unmodified graphene oxide (GO) onto the microstructure as well as the mechanical properties of Al₂O₃/TiB₂ matrix ceramic materials. The microstructure observation revealed that, compared with GO addition, the addition of Al₂O₃–RGO nanoparticles significantly improved RGO dispersion in the ceramic materials and reduced defects such as pores caused by graphene agglomeration. In addition, the uniformly dispersed RGO nanosheets were interwoven with each other to form a three-dimensional grid structure due to grain growth and the disappearance of pores during sintering, which increased the contact area and interface-bonding strength between the RGO and ceramic matrix. According to the results of microstructure observation and analysis, the good interfacial strength not only facilitated load transfer from the ceramic matrix to the RGO but also induced the fracture mechanism of the RGO, which consumes more fracture energy than the traditional toughening mechanism. The results of mechanical properties analysis showed that the hardness, flexural strength, and fracture toughness of the obtained ATB–RG3.0 ceramic material was measured at 19.52 GPa, 1063.52 MPa, and 9.16 MPa·m1/2, respectively. These values are 16.82%, 27.92%, and 26.87% higher than those of the ceramic material with 3.0 vol.% GO. Full article

(This article belongs to the Special Issue Advanced Technologies in Graphene-Based Materials (2nd Edition))

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14 pages, 12889 KiB

Open AccessArticle

Wear Behaviour of Graphene-Reinforced Ti-Cu Waste-Metal Friction Composites Fabricated with Spark Plasma Sintering

by Mária Podobová, Viktor Puchý, Richard Sedlák, Dávid Medveď, Róbert Džunda and František Kromka

Crystals 2024, 14(11), 948; https://doi.org/10.3390/cryst14110948 - 31 Oct 2024

Abstract

In this study, we fabricated Ti-Cu-based friction composites containing waste-metal (Ti, CuZn, stainless steel (SSt), MgAl), Al₂O₃ due to improving properties and its good compatibility with copper and graphene nanoplatelets as reinforcement and lubricant component, using planetary ball mill and [...] Read more.

In this study, we fabricated Ti-Cu-based friction composites containing waste-metal (Ti, CuZn, stainless steel (SSt), MgAl), Al₂O₃ due to improving properties and its good compatibility with copper and graphene nanoplatelets as reinforcement and lubricant component, using planetary ball mill and technique based on Spark Plasma Sintering (SPS). Understanding the wear behaviour of such engineered friction composites is essential to improve their material design and safety, as these materials could have the potential for use in public and industrial transportation, such as high-speed rail trains and aircraft or cars. This is why our study is focused on wear behaviour during friction between function parts of devices. We investigated the composite materials designed by us in order to clarify their microstructural state and mechanical properties. Using different loading conditions, we determined the Coefficient of Friction (COF) using a ball-on-disc tribological test. We analysed the state of the samples after the mentioned test using a Scanning Electron Microscope (SEM), then Energy-Dispersive X-ray Spectroscopy (EDS), and confocal microscopy. Also, a comparative analysis of friction properties with previously studied materials was performed. The results showed that friction composites with different compositions, despite the same conditions of their compaction during sintering, can be defined by different wear characteristics. Our study can potentially have a significant contribution to the understanding of wear mechanisms of Ti-Cu-based composites with incorporated metal-waste and to improving their material design and performance. Also, it can give us information about the possibilities of reusing metal-waste from different machining operations. Full article

(This article belongs to the Special Issue Processing, Structure and Properties of Metal Matrix Composites)

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11 pages, 12399 KiB

Open AccessArticle

Influence of Various Binder Jet Printers on the Additive Manufacturing of Hardmetals

by Christian Berger, Johannes Pötschke, Uwe Scheithauer and Alexander Michaelis

Crystals 2024, 14(11), 947; https://doi.org/10.3390/cryst14110947 - 31 Oct 2024

Abstract

Binder Jetting (BJT), a powder-based additive manufacturing technology, has been shown to be a fast and reproducible green shaping process for many different metals. Due to its high productivity and versatility in material processing, BJT is gaining increasing importance in the manufacturing sector. [...] Read more.

Binder Jetting (BJT), a powder-based additive manufacturing technology, has been shown to be a fast and reproducible green shaping process for many different metals. Due to its high productivity and versatility in material processing, BJT is gaining increasing importance in the manufacturing sector. It can also be used for the production of WC-Co hardmetals, a primary ceramic-based composite often used for tools and wear parts. Five different BJT printers from four different manufacturers were evaluated to assess their effectiveness and feasibility in producing hardmetals based on the same WC-12 wt.% Co starting powders. The analysis focused on comparing the properties of the resulting hardmetals, as well as evaluating the printing performance. The results show that all tested BJT printers are fundamentally well suited for producing green hardmetal parts, which can achieve full density after sintering. This work highlights the potential of BJT technology in hardmetal manufacturing for tool production. Full article

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

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15 pages, 4320 KiB

Open AccessArticle

Influence of Heat Treatment on the Microstructure and Tensile Properties of a Novel Nitrogenous Nickel-Based Deposited Metal

by Yingdi Wang, Zhiyong Dai and Yunhai Su

Crystals 2024, 14(11), 946; https://doi.org/10.3390/cryst14110946 - 30 Oct 2024

Abstract

Nitrogenous nickel-based deposited metal was prepared by using the gas metal arc welding (GMAW) method, and it was further subjected to solid-solution and aging heat treatment. The influence of different solid-solution temperatures on the microstructure of the deposited metal was studied, and the [...] Read more.

Nitrogenous nickel-based deposited metal was prepared by using the gas metal arc welding (GMAW) method, and it was further subjected to solid-solution and aging heat treatment. The influence of different solid-solution temperatures on the microstructure of the deposited metal was studied, and the complete heat treatment system for the nitrogenous nickel-based deposited metal was ultimately determined. The microstructure, mechanical properties, and deformation mechanism of the nitrogenous nickel-based deposited metal in two states (as-prepared state and complete heat-treated state) were finally investigated. The results show that the microstructure of the deposited metal mainly consisted of epitaxially grown columnar grains with large grains. Petal-like Laves phases formed between the dendrites. The main deformation mechanism was the unit dislocation a/2<110> cut precipitation phase. After a complete heat treatment, all the Laves phases were re-melted, and nanoscale M(C,N) phases precipitated in the grains, while M₂₃C₆ phases formed at the grain boundaries. The samples showed higher yield and ultimate tensile strengths than those of the as-prepared state metal, but with reduced ductility. The deformation mechanism involved not only a/2<110> matrix dislocations cutting the precipitated phase, but also two a/6<121> Shockley incomplete dislocations, together cutting the precipitated phase to form a stacking layer dislocation. Full article

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

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12 pages, 10251 KiB

Open AccessArticle

Surface Modification and Tribological Performance of Calcium Phosphate Coatings with TiO₂ Nanoparticles on VT1-0 Titanium by Micro-Arc Oxidation

by Bauyrzhan Rakhadilov, Ainur Zhassulan, Kuanysh Ormanbekov, Aibek Shynarbek, Daryn Baizhan and Tamara Aldabergenova

Crystals 2024, 14(11), 945; https://doi.org/10.3390/cryst14110945 - 30 Oct 2024

Abstract

The continuous development of biomedical materials necessitates exploring new solutions to enhance implant performance. This study investigates the impact of titanium dioxide nanoparticles on calcium phosphate coatings applied to VT1-0 titanium substrates using micro-arc oxidation. Titanium, widely recognized for its excellent mechanical properties [...] Read more.

The continuous development of biomedical materials necessitates exploring new solutions to enhance implant performance. This study investigates the impact of titanium dioxide nanoparticles on calcium phosphate coatings applied to VT1-0 titanium substrates using micro-arc oxidation. Titanium, widely recognized for its excellent mechanical properties and compatibility, serves as an ideal substrate for implants. The coatings were synthesized in an electrolyte with varying titanium dioxide concentrations to examine their influence on surface morphology, wettability, roughness, hardness, and tribological characteristics. Characterization techniques, such as scanning electron microscopy, X-ray diffraction, and profilometry, were employed to analyze the coatings’ structural and mechanical properties. The results demonstrate that increasing titanium dioxide concentrations leads to enhanced uniformity, reduced pore sizes, and higher hardness. Furthermore, the coatings showed improved wear resistance and reductions in friction coefficients at optimal nanoparticle levels. The inclusion of titanium dioxide significantly enhances the mechanical and tribological performance of the calcium phosphate coatings, making them suitable for biomedical applications, especially in implants requiring long-term durability and enhanced compatibility. Full article

(This article belongs to the Topic Microstructure and Properties in Metals and Alloys, 3rd Volume)

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10 pages, 2866 KiB

Open AccessArticle

A New Heterometallic Silver/Cadmium Thiocyanate Directed by Benzyl Viologen Possessing Photocurrent Response and Photocatalytic Degradation on Rhodamine B in Artificial Seawater

by Xueqiang Zhuang, Xihe Huang, Haohong Li, Tianjin Lin and Yali Gao

Crystals 2024, 14(11), 944; https://doi.org/10.3390/cryst14110944 - 30 Oct 2024

Abstract

The search for new heterometallic metal pseudohalides will be significant for the development of novel functional materials. In this work, a new silver/cadmium heterometallic thiocyanate templated by benzyl viologen has been synthesized and structurally determined, i.e., {(BV)[Ag₂Cd(SCN)₆]}_n (BV [...] Read more.

The search for new heterometallic metal pseudohalides will be significant for the development of novel functional materials. In this work, a new silver/cadmium heterometallic thiocyanate templated by benzyl viologen has been synthesized and structurally determined, i.e., {(BV)[Ag₂Cd(SCN)₆]}_n (BV²⁺ = benzyl viologen). The interesting 1-D double chain [Ag₂Cd(SCN)₆]_n²ⁿ⁻ was constructed from the CdN₆ octahedron and Ag₂SCN₆ dimers via μ₂-SCN and μ₃-S,S N SCN bridge, in which the Ag···Ag interaction can be found. Inter-molecular C-H···S/N hydrogen bonds between BV²⁺ cations and [Ag₂Cd(SCN)₆]_n²ⁿ⁻ chains contribute to the formation of a stable 3-D network. The short S···N distance implies the strong charge transfer (CT) interactions between the electron-rich silver/cadmium thiocyanate donor and BV²⁺ acceptor. This hybrid can exhibit a photo-generated current performance with an intensity of 1.75 × 10⁻⁸ A. Interestingly, this hybrid can present good photocatalytic degradation performance on rhodamine B in artificial seawater with a degradation ratio of 86.5% in 240 min. This work provides a new catalyst way for the organic dye-type ocean pollutant treatments. Full article

(This article belongs to the Topic Microstructure and Properties in Metals and Alloys, 3rd Volume)

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12 pages, 3517 KiB

Open AccessArticle

A Fluorescence Sensor Based on Biphenolic Backbone for Metal Ion Detection: Synthesis and Crystal Structure

by Kanokporn Chantaniyomporn, Kiratikarn Charoensuk, Tanwawan Duangthongyou, Kittipong Chainok and Boontana Wannalerse

Crystals 2024, 14(11), 943; https://doi.org/10.3390/cryst14110943 - 30 Oct 2024

Abstract

2′-(hexyloxy)-[1,1′-biphenyl]-2-yl 5-(dimethylamino)naphthalene-1-sulfonate (KC1) was synthesized by using biphenol and dansyl chloride as starting materials. The KC1 was characterized via single X-ray diffraction, FTIR, HRMS and ¹H and ¹³C-NMR. The KC1 indicates triclinic as P1 in the space group type. From the [...] Read more.

2′-(hexyloxy)-[1,1′-biphenyl]-2-yl 5-(dimethylamino)naphthalene-1-sulfonate (KC1) was synthesized by using biphenol and dansyl chloride as starting materials. The KC1 was characterized via single X-ray diffraction, FTIR, HRMS and ¹H and ¹³C-NMR. The KC1 indicates triclinic as P1 in the space group type. From the KC1, the biphenolic backbone structure is twisted at an angle of 54.48° due to connecting the dansyl unit and hexyl moiety. Upon the addition of the Fe³⁺ ion to the KC1 solution, the fluorescence emission at 585 nm of KC1 was quenched due to complexation between KC1 and the Fe³⁺ ion. The complexation ratio of KC1 and Fe³⁺ was determined to be a 1:1 formation via Job’s analysis. The Stern–Volmer constant (K_sv) calculated was 21,203 M⁻¹ for the KC1 and the Fe³⁺ ion complex. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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11 pages, 2349 KiB

Open AccessArticle

Structural and Optical Properties of SrTiO₃-Based Ceramics for Energy and Electronics Applications

by Donghoon Kim, Soyeon Gwon, Kyeongsoon Park and Eui-Chan Jeon

Crystals 2024, 14(11), 942; https://doi.org/10.3390/cryst14110942 - 30 Oct 2024

Abstract

A series of Sr_1−xDy_xTi_1−yNb_yO_3−δ (0.05 ≤ x, y ≤ 0.10) samples were fabricated using cold compaction, followed by sintering in a (95% N₂ + 5% H₂) reducing [...] Read more.

A series of Sr_1−xDy_xTi_1−yNb_yO_3−δ (0.05 ≤ x, y ≤ 0.10) samples were fabricated using cold compaction, followed by sintering in a (95% N₂ + 5% H₂) reducing atmosphere. We studied the crystal structure and optical properties of Sr_1−xDy_xTi_1−yNb_yO_3−δ using X-ray diffraction (XRD) with Rietveld refinement, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet−visible−near-infrared (UV−VIS−NIR) spectroscopy. The sintered Sr_1−xDy_xTi_1−yNb_yO_3−δ had a tetragonal structure (I4/mcm space group). In the sintered samples, Ti ions existed as a mixture of Ti³⁺ and Ti⁴⁺, and Nb ions existed as a mixture of Nb⁴⁺ and Nb⁵⁺. The band-gap energies decreased with increasing Dy/Nb concentrations. The incorporation of Ti and Nb ions, the formation of both Ti³⁺ and Nb⁴⁺ ions, and the reduction in band-gap energies are likely highly effective for increasing the electron concentration and the corresponding electrical conductivity. Sr_1−xDy_xTi_1−yNb_yO_3−δ with high electrical conductivity is suitable for energy and electronics applications. Full article

(This article belongs to the Special Issue Precision and Ultra-Precision Machining for Ceramics and Composite Materials)

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13 pages, 7188 KiB

Open AccessArticle

Structural, Morphological, and Optical Properties of Nano- and Micro-Structures of ZnO Obtained by the Vapor–Solid Method at Atmospheric Pressure and Photocatalytic Activity

by Carlos Bueno, Adan Luna, Gregorio Flores, Héctor Juárez, Mauricio Pacio, René Pérez, Javier Flores-Méndez, David Maestre and Raúl Cortés-Maldonado

Crystals 2024, 14(11), 941; https://doi.org/10.3390/cryst14110941 - 30 Oct 2024

Abstract

Micro- and nano-structures of ZnO were synthesized by the vapor–solid method at 600, 700, and 800 °C in atmospheres of Ar and air, at atmospheric pressure. The structural characterization XRD shows that the nano-structures synthesized in air atmosphere at 600 °C, while diffraction [...] Read more.

Micro- and nano-structures of ZnO were synthesized by the vapor–solid method at 600, 700, and 800 °C in atmospheres of Ar and air, at atmospheric pressure. The structural characterization XRD shows that the nano-structures synthesized in air atmosphere at 600 °C, while diffraction peaks were found due to Zn because the presence of metallic Zn remains on the surface of the pellet. SEM images show that the morphologies range from nano-wires to micro-tubes. When cathodoluminescence is measured in micro-tubes, there is a shift of the near-band edge of the ZnO toward red; this is due to structural defects in the ZnO network. This result is corroborated with panchromatic CL measurements, which exhibit a difference in brightness between the micro-tubes. Furthermore, EDS measurements show an atomic quantity ratio of Zn:O that differs from the stoichiometric composition in the micro-tubes. The photocatalytic activity of three types of structures—nano-wires, micro-tubes, and micro-rods under UV irradiation using methylene blue as a model pollutant—were evaluated. The best response was obtained for nanowires, not only because they have a larger surface area but also because of the present defects. Full article

(This article belongs to the Special Issue Advances in Crystal Growth: Pioneering Materials for Tomorrow's Technologies)

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