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Crystals
Volume 14
Issue 9
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Crystals, Volume 14, Issue 9 (September 2024) – 81 articles

Cover Story (view full-size image): This study addresses this gap by conducting a comprehensive investigation of potential catalysts for nitrogen electro-reduction to ammonia under ambient conditions. Using density functional theory calculations, we explore the (110) facets of rock salt structures across 11 transition metal carbides. Catalytic activity is evaluated through the construction of free energy diagrams for associative, dissociative, and Mars–van Krevelen reaction mechanisms. Additionally, we assess material stability against electrochemical poisoning and decomposition of parent metals during operation. Our findings suggest that a few of the candidates are promising for nitrogen reduction reactions, such as TaC and WC, with moderate onset potentials (−0.66 V and −0.82 V vs. RHE) under ambient conditions. View this paper
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16 pages, 8853 KiB  
Article
Titanium Nitride as an Alternative Plasmonic Material for Plasmonic Enhancement in Organic Photovoltaics
by Atacan Tütüncüoğlu, Meral Yüce and Hasan Kurt
Crystals 2024, 14(9), 828; https://doi.org/10.3390/cryst14090828 - 23 Sep 2024
Cited by 1 | Viewed by 670
Abstract
This paper investigates TiN for its potential to enhance light-harvesting efficiency as an alternative material to Au for nanoscale plasmonic light trapping in thin-film solar cells. Using nanosphere lithography (NSL), plasmonic arrays of both Au and TiN are fabricated and characterized. Later, the [...] Read more.
This paper investigates TiN for its potential to enhance light-harvesting efficiency as an alternative material to Au for nanoscale plasmonic light trapping in thin-film solar cells. Using nanosphere lithography (NSL), plasmonic arrays of both Au and TiN are fabricated and characterized. Later, the fabricated TiN and Au arrays are integrated into a thin-film organic photovoltaic (OPV) device with a PBDB-T:ITIC-M bulk heterojunction (BHJ) active layer. A comparative study between these Au and TiN nanostructured arrays evaluates their fabrication process and plasmonic response, highlighting the advantages and disadvantages of TiN compared to a conventional plasmonic material such as Au. The effect of the fabricated arrays when integrated into an OPV is presented and compared to understand the viability of TiN. As one of the first experimental studies utilizing TiN arrays for the plasmonic enhancement of photovoltaics, the results offer valuable insight that can guide future applications and decisions in design. Full article
(This article belongs to the Special Issue New Trends in Magnetic, Dielectric, Electrical, Optical, and Thermal Properties of Crystalline Materials)
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13 pages, 29741 KiB  
Article
Effect of Initial Intergranular Ferrite Size on Induction Hardening Microstructure of Microalloyed Steel 38MnVS6
by Dequn Kong, Jian Zhou, Weiwei Dong, Li Cai and Chunyu Qu
Crystals 2024, 14(9), 827; https://doi.org/10.3390/cryst14090827 - 22 Sep 2024
Viewed by 946
Abstract
In this study, we investigated the effect of grain size of an initial microstructure (pearlite + ferrite) on a resulting microstructure of induction-hardened microalloyed steel 38MnVS6, which is one topical medium carbon vanadium microalloyed non-quenched and tempered steel used in manufacturing crankshafts for [...] Read more.
In this study, we investigated the effect of grain size of an initial microstructure (pearlite + ferrite) on a resulting microstructure of induction-hardened microalloyed steel 38MnVS6, which is one topical medium carbon vanadium microalloyed non-quenched and tempered steel used in manufacturing crankshafts for high-power engines. The results show that a coarse initial microstructure could contribute to the incomplete transformation of pearlite + ferrite into austenite in reaustenitization transformation by rapid heating, and the undissolved ferrite remains and locates between the neighboring prior austenite grains after the induction-hardening process. As the coarseness level of the initial microstructure increases from 102 μm to 156 μm, the morphology of undissolved ferrite varies as granule, film, semi-network, and network, in sequence. The undissolved ferrite structures have a thickness of 250–500 nm and appear dark under an optical metallographic view field. To achieve better engineering applications, it is not recommended to eliminate the undissolved ferrite by increasing much heating time for samples with coarser initial microstructures. It is better to achieve a fine original microstructure before the induction-hardening process. For example, microalloying addition of vanadium and titanium plays a role of metallurgical grain refinement via intragranular ferrite nucleation on more sites, and the heating temperature and time of the forging process should be strictly controlled to ensure the existence of fine prior austenite grains before subsequent isothermal phase transformation to pearlite + ferrite. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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17 pages, 505 KiB  
Article
General Properties of Conventional and High-Temperature Superconductors
by Vasily R. Shaginyan, Alfred Z. Msezane and Stanislav A. Artamonov
Crystals 2024, 14(9), 826; https://doi.org/10.3390/cryst14090826 - 21 Sep 2024
Viewed by 735
Abstract
In our review, we analyze the scaling of the condensation energy EΔ divided by γ, EΔ/γ≃N(0)Δ12/γ, and quasiparticles of both conventional and unconventional superconductors, where [...] Read more.
In our review, we analyze the scaling of the condensation energy EΔ divided by γ, EΔ/γ≃N(0)Δ12/γ, and quasiparticles of both conventional and unconventional superconductors, where N(0) is the density of states at zero temperature T=0, Δ1 is the maximum value of the superconducting gap, and γ is the Sommerfeld coefficient. It is shown that Bogoliubov quasiparticles act in superconducting states of unconventional and conventional superconductors. At the same time, quasiparticles are also present in the normal state of unconventional superconductors. We briefly describe the difference between unconventional superconductors and conventional ones, such as the resistivity in normal states and the difference in superfluid density in superconducting states. For the first time, we theoretically show that the universal scaling of EΔ/γ∝Tc2 applies equally to both conventional and unconventional superconductors. Our consideration is based on two experimental facts: Bogoliubov quasiparticles act in conventional and non-conventional superconductors and the corresponding flat band is deformed by the non-conventional superconducting state. As a result, our theoretical observations based on the theory of fermion condensation agree well with the experimental facts. Full article
(This article belongs to the Section Materials for Energy Applications)
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21 pages, 4302 KiB  
Article
Multiaxial Fatigue Lifetime Estimation Based on New Equivalent Strain Energy Damage Model under Variable Amplitude Loading
by Zhi-Qiang Tao, Xiangnan Pan, Zi-Ling Zhang, Hong Chen and Li-Xia Li
Crystals 2024, 14(9), 825; https://doi.org/10.3390/cryst14090825 - 20 Sep 2024
Viewed by 759
Abstract
The largest normal stress excursion during contiguous turn time instants of the maximum torsional stress is presented as an innovative path-independent fatigue damage quantity upon the critical plane, which is further employed for characterizing fatigue damage under multiaxial loading. Via using the von [...] Read more.
The largest normal stress excursion during contiguous turn time instants of the maximum torsional stress is presented as an innovative path-independent fatigue damage quantity upon the critical plane, which is further employed for characterizing fatigue damage under multiaxial loading. Via using the von Mises equivalent stress formula, an axial stress amplitude with equivalent value is proposed, incorporating the largest torsional stress range and largest normal stress excursion upon the critical plane. The influence of non-proportional cyclic hardening is considered within the presented axial equivalent stress range. Moreover, according to proposed axial equivalent stress amplitude, an energy-based damage model is presented to estimate multiaxial fatigue lifetime upon the critical plane. In order to verify the availability of the proposed approach, the empirical results of a 7050-T7451 aluminum alloy and En15R steel are used, and the predictions indicated that estimated fatigue lives correlate with the experimentally observed fatigue results well for variable amplitude multiaxial loadings. Full article
(This article belongs to the Special Issue Fatigue and Fracture of Crystalline Metal Structures)
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15 pages, 6969 KiB  
Article
Effects of Continuous Rolling and Reversible Rolling on 2.4% Si Non-Oriented Silicon Steel
by Kaixuan Shao, Yuhao Niu, Yinghao Pei, Jialong Qiao, Hongbo Pan and Haijun Wang
Crystals 2024, 14(9), 824; https://doi.org/10.3390/cryst14090824 - 20 Sep 2024
Viewed by 608
Abstract
The cold-rolled non-oriented silicon steel sheets with a Si content of 2.4 wt.%, produced by continuous and reversible cold rolling, were used as the experimental material. The effects of annealing temperature on the microstructure, texture, and magnetic properties were studied by optical microscopy, [...] Read more.
The cold-rolled non-oriented silicon steel sheets with a Si content of 2.4 wt.%, produced by continuous and reversible cold rolling, were used as the experimental material. The effects of annealing temperature on the microstructure, texture, and magnetic properties were studied by optical microscopy, an X-ray diffractometer, and a magnetic property measuring instrument. The experimental results showed that the dominant texture components at the surface of both sheets were almost the same, i.e., α and γ fibers. After annealing at 920 °C for 30 s, a complete recrystallization occurred in both sheets. When annealing below 1070 °C, the average grain sizes of continuous cold-rolled sheets were slightly higher than those of reversible cold-rolled ones. Additionally, for all specimens, the recrystallization texture components were γ fiber, as well as weak α fiber, λ fiber, and Goss texture. Additionally, the difference was the texture intensity. The iron losses of the finished products of continuous cold rolling were lower than those of the finished products of reversible cold rolling with the increase in annealing temperature, and the magnetic induction was higher than that of the finished products of reversible cold rolling. Full article
(This article belongs to the Special Issue Crystallization of High Performance Metallic Materials (2nd Edition))
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27 pages, 6432 KiB  
Review
Supramolecular Arrangement and Conformational and Dynamic Properties of Chiral Smectic Liquid Crystals Obtained through Nuclear Magnetic Resonance: A Brief Review
by Valentina Domenici
Crystals 2024, 14(9), 823; https://doi.org/10.3390/cryst14090823 - 20 Sep 2024
Viewed by 577
Abstract
Ferroelectric and antiferroelectric smectic liquid crystalline (LC) phases are still at the center of investigations and interests for both their fundamental properties and variety of technological applications. This review aims to report the main contributions based on different nuclear magnetic resonance (NMR) techniques [...] Read more.
Ferroelectric and antiferroelectric smectic liquid crystalline (LC) phases are still at the center of investigations and interests for both their fundamental properties and variety of technological applications. This review aims to report the main contributions based on different nuclear magnetic resonance (NMR) techniques to the study of chiral liquid crystalline calamitic mesogens forming smectic phases, such as the SmA, the SmC* (ferroelectric), and the SmC*A (antiferroelectric) phases. 2H NMR and 13C NMR techniques and their combination were of help in clarifying the local orientational properties (i.e., the molecular and fragments’ main orientational order parameters) at the transition between the SmA and the SmC* phases, and in the particular case of de Vries liquid crystals, NMR studies gave important clues regarding the actual models describing the molecular arrangement in these two phases formed by de Vries LCs. Moreover, this review describes how the combination of 2H NMR relaxation times’ analysis, 1H NMR relaxometry, and 1H NMR diffusometry was successfully applied to the study of chiral smectogens forming the SmC* and SmC*A phases, with the determination of relevant parameters describing both rotational molecular and internal motions, collective dynamics, and translational self-diffusion motions. Several cases will be reported concerning NMR investigations of chiral ferroelectric and antiferroelectric phases, underlining the great potential of combined NMR approaches to the study of supramolecular, conformational, and dynamic properties of liquid crystals. Full article
(This article belongs to the Section Liquid Crystals)
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11 pages, 858 KiB  
Article
Two-Dimensional Electron Gas in Thin N-Polar GaN Channels on AlN on Sapphire Templates
by Markus Pristovsek, Itsuki Furuhashi, Xu Yang, Chengzhi Zhang and Matthew D. Smith
Crystals 2024, 14(9), 822; https://doi.org/10.3390/cryst14090822 - 20 Sep 2024
Viewed by 889
Abstract
We report on 2-dimensional electron gases realized in binary N-polar GaN channels on AlN on sapphire templates grown by metal–organic vapor phase epitaxy. The measured sheet carrier density of 3.8×1013 cm−2 is very close to the theoretical value of [...] Read more.
We report on 2-dimensional electron gases realized in binary N-polar GaN channels on AlN on sapphire templates grown by metal–organic vapor phase epitaxy. The measured sheet carrier density of 3.8×1013 cm−2 is very close to the theoretical value of 3.95×1013 cm−2 due to the low carbon and oxygen background doping in the N-polar GaN if grown with triethyl-gallium. By inserting an intermediate AlN transition layer, room temperature mobilities in 5 nm channels up to 100 cm2/Vs were realized, probably limited by dislocations and oxygen background in N-polar AlN. Thicker channels of 8 nm or more showed relaxation and thus much lower mobilities. Full article
(This article belongs to the Special Issue Recent Advances in III-Nitride Semiconductors and Correlated Wide Bandgap Semiconductors, 2nd Edition)
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15 pages, 4176 KiB  
Article
Study on the Simulation and Experimental Impact of Substrate Holder Design on 3-Inch High-Quality Polycrystalline Diamond Thin Film Growth in a 2.45 GHz Resonant Cavity MPCVD
by Shuai Wu, Kesheng Guo, Jie Bai, Jiafeng Li, Jingming Zhu, Lei Liu, Lei Huang, Chuandong Zhang and Qiang Wang
Crystals 2024, 14(9), 821; https://doi.org/10.3390/cryst14090821 - 20 Sep 2024
Viewed by 600
Abstract
In this study, three different substrate holder shapes—trapezoidal, circular frustum, and adjustable cyclic—were designed and optimized to enhance the quality of polycrystalline diamond films grown using microwave plasma chemical vapor deposition (MPCVD). Simulation results indicate that altering the shape of the substrate holder [...] Read more.
In this study, three different substrate holder shapes—trapezoidal, circular frustum, and adjustable cyclic—were designed and optimized to enhance the quality of polycrystalline diamond films grown using microwave plasma chemical vapor deposition (MPCVD). Simulation results indicate that altering the shape of the substrate holder leads to a uniform distribution of the electric field on the surface, significantly suppressing the formation of secondary plasma. This design ensures a more even distribution of the temperature field and plasma environment on the substrate holder, resulting in a heart-shaped distribution. Polycrystalline diamond films were synthesized under these three different substrate holder conditions, and their morphology and crystal quality were characterized using optical microscopy, Raman spectroscopy, and high-resolution X-ray diffraction. Under conditions of 5 kW power and 90 Torr pressure, the adjustable cyclic substrate holder produced high-quality 3-inch diamond films with low stress and narrow Raman full width at half maximum (FWHM). The results confirm the reliability of the simulations and the effectiveness of the adjustable cyclic substrate holder. This approach provides a viable method for scaling up the size and improving the quality of polycrystalline diamond films for future applications. Full article
(This article belongs to the Special Issue Advances in Synthesis, Characterization, and Application of Thin Films)
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26 pages, 9568 KiB  
Article
Technology for Obtaining Sintered Components with Tailored Electromagnetic Features by Selective Recycling of Printed Circuit Boards
by Romeo Cristian Ciobanu, Mihaela Aradoaei and Cristina Schreiner
Crystals 2024, 14(9), 820; https://doi.org/10.3390/cryst14090820 - 20 Sep 2024
Viewed by 596
Abstract
The paper presents a technological approach for obtaining sintered components with tailored electromagnetic features from electromagnetically active powders through the selective recycling of electronic waste, in particular scrap electronic components. Printed circuit board (PCB) scraps were submitted to a succession of grinding processes, [...] Read more.
The paper presents a technological approach for obtaining sintered components with tailored electromagnetic features from electromagnetically active powders through the selective recycling of electronic waste, in particular scrap electronic components. Printed circuit board (PCB) scraps were submitted to a succession of grinding processes, followed by progressive magnetic and electrostatic separation, resulting two final fractions: metallic particles and non-metallic particles including different metallic oxides. Three types of powders were analyzed, i.e., powder after fine grinding, after magnetic separation and after electrostatic separation, which were further processed within a spark plasma sintering furnace in order to obtain solid disk samples. All samples contained several classes of oxides, and also residual metals, leading to specific thermal decomposition processes at different temperatures, depending on the nature of the oxides present in the studied materials. The chemical analysis of powders, via spectrometry with X-ray fluorescence—XRF, emphasized the presence of a mixture of metal oxides and traces of metals (mainly Ag), with concentrations diminishing along with the purification process. The most important analysis was related to dielectric parameters, and it was concluded that the powders obtained by the proposed technology could efficiently substitute scarce raw materials actually used as additives in composites, coatings and paints, mainly due to their high permittivity (above 6 in all frequency domains) and, respectively, dielectric loss factor (above 0.2 in all cases, in all frequency domains). We estimate that the technology described in this paper is a sustainable one according to the concept of circular economy, as it could reduce, by a minimum of 15%, the embodied GHG emissions generated from information and communications technology (ICT) devices by advanced recycling. Full article
(This article belongs to the Section Hybrid and Composite Crystalline Materials)
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18 pages, 5331 KiB  
Article
Flow Stress Constitutive Relation of S280 Ultrahigh Strength Stainless Steel
by Mutong Liu, Xiaochang Xie, Ye Tian, Yuwei Xia, Kelu Wang and Shiqiang Lu
Crystals 2024, 14(9), 819; https://doi.org/10.3390/cryst14090819 - 20 Sep 2024
Viewed by 448
Abstract
Isothermal constant-strain-rate compression experiments of S280 ultrahigh-strength stainless steel were conducted at 800–1150 °C, 0.001–10 s−1, and 70% height reduction. The flow stress behaviors were analyzed based on the compression data. The strain compensation Arrhenius constitutive relation, multiple linear regression constitutive [...] Read more.
Isothermal constant-strain-rate compression experiments of S280 ultrahigh-strength stainless steel were conducted at 800–1150 °C, 0.001–10 s−1, and 70% height reduction. The flow stress behaviors were analyzed based on the compression data. The strain compensation Arrhenius constitutive relation, multiple linear regression constitutive relation, and back-propagation (BP) neural network constitutive relation of this alloy were established for the first time. The S280 ultrahigh-strength stainless steel is characterized by a positive strain rate and negative temperature sensitivity. Its flow stress at high temperature (1000–1150 °C) and low temperature (800–950 °C) is generally at the steady state and the softening state, respectively. The three new flow stress constitutive relations all meet the requirements for engineering applications in terms of predictive precision. The BP neural network constitutive relation shows the highest predictive precision, with correlation coefficient R of 0.999 and average absolute relative error AARE of 1.04%. The strain compensation Arrhenius constitutive relation shows the lowest predictive precision, with R of 0.994 and AARE of 14.748%. The multiple linear regression constitutive relation shows the modest predictive precision, with R of 0.994 and AARE of 6.24%. Full article
(This article belongs to the Special Issue Microstructure and Deformation of Advanced Alloys)
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35 pages, 3346 KiB  
Review
Recent Advances in Ammonia Synthesis Modeling and Experiments on Metal Nitrides and Other Catalytic Surfaces
by Numair Elahi and Constantinos D. Zeinalipour-Yazdi
Crystals 2024, 14(9), 818; https://doi.org/10.3390/cryst14090818 - 18 Sep 2024
Viewed by 1997
Abstract
In this review, we explore the recent progress in catalytic materials for the ammonia syntheses that are based on metal nitrides and other catalytic surfaces. It comprises a detailed overlook of the various techniques used in ammonia synthesis research and the state-of-the-art modeling [...] Read more.
In this review, we explore the recent progress in catalytic materials for the ammonia syntheses that are based on metal nitrides and other catalytic surfaces. It comprises a detailed overlook of the various techniques used in ammonia synthesis research and the state-of-the-art modeling techniques employed to investigate new reaction mechanisms and more efficient processes for sustainable ammonia synthesis production. The review is discussed in the context of the reaction mechanisms developed and the recent progress that has been made with respect to thermal, electrochemical, and photocatalytic ammonia synthesis. Full article
(This article belongs to the Section Materials for Energy Applications)
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14 pages, 3840 KiB  
Article
Crystal Structure, Microstructure, and Dielectric and Electrical Properties of Ceramic Material Prepared Using Volcanic Ash
by Shoroog Alraddadi
Crystals 2024, 14(9), 817; https://doi.org/10.3390/cryst14090817 - 18 Sep 2024
Cited by 1 | Viewed by 758
Abstract
In the present work, the electrical and dielectric properties of ceramic samples prepared from volcanic ash were investigated. For this purpose, ceramic samples were prepared using milled volcanic ash with a binder material at a sintering temperature of 950 °C for 2 h. [...] Read more.
In the present work, the electrical and dielectric properties of ceramic samples prepared from volcanic ash were investigated. For this purpose, ceramic samples were prepared using milled volcanic ash with a binder material at a sintering temperature of 950 °C for 2 h. The chemical content of the milled volcanic ash was investigated using XRF. Differential thermal analysis and thermogravimetry were performed to determine the firing conditions. The crystalline phases and microstructures of the ceramic samples were investigated using XRD and SEM, respectively. Finally, the electrical and dielectric properties of the obtained samples were evaluated at a frequency ranging from 1 × 102 to 4 × 106 Hz and temperatures ranging from room temperature to 800 °C. The XRD results revealed that the ceramic samples contained three main phases: albite, hematite, and augite. Moreover, the microstructures of the samples exhibited a large crystal size with a dense surface. The conductivities and dielectric constants of the samples remained stable up to 500 °C. The real and imaginary parts of the dielectric constant decreased with an increase in frequency and increased with an increase in temperature. The results indicated that ceramics based on volcanic ash are promising for use in technological applications such as high-voltage power insulators. Full article
(This article belongs to the Section Polycrystalline Ceramics)
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11 pages, 3352 KiB  
Article
Impact of Mg on the Feeding Ability of Cast Al–Si7–Mg(0_0.2_0.4_0.6) Alloys
by Mile Djurdjevic, Srecko Manasijevic, Aleksandra Patarić, Srecko Stopic and Marija Mihailović
Crystals 2024, 14(9), 816; https://doi.org/10.3390/cryst14090816 - 17 Sep 2024
Viewed by 605
Abstract
The demand for high-performance Al–Si casting alloys is driven by their mechanical properties, making them popular in automotive, aerospace, and engineering industries. These alloys, especially hypoeutectic Al–Si–Mg, offer benefits like high fluidity, low thermal expansion, and good corrosion resistance. Silicon and magnesium primarily [...] Read more.
The demand for high-performance Al–Si casting alloys is driven by their mechanical properties, making them popular in automotive, aerospace, and engineering industries. These alloys, especially hypoeutectic Al–Si–Mg, offer benefits like high fluidity, low thermal expansion, and good corrosion resistance. Silicon and magnesium primarily define their microstructure and mechanical properties. Silicon enhances fluidity, while magnesium improves strength and fatigue resistance. However, challenges like shrinkage porosity persist during solidification. Understanding solidification feeding regions is crucial, influenced by factors such as chemical composition, solidification characteristics, and casting design. This study investigates magnesium’s influence on feeding ability in hypoeutectic Al–Si7–Mg alloys through experimental tests. Increasing magnesium content from 0% to 0.6% affects the interdendritic and burst feeding regions. This could impact shrinkage porosity formation. The “Sand Hourglass” test results indicate a rise in porosity levels with higher magnesium content, which is linked to the narrowing of interdendritic channels and the formation of magnesium-rich intermetallic compounds. These changes hinder the liquid metal flow, worsening shrinkage porosity. Therefore, magnesium’s role in expanding the interdendritic region is a key factor in developing porosity in cast hypoeutectic Al–Si7–Mg alloys. This study highlights that porosity levels increase from 0% in magnesium-free Al–Si7 to 0.84% in Al–Si7–Mg0.6, underscoring magnesium’s significant impact on the occurrence of porosity in these alloys. Full article
(This article belongs to the Special Issue Microstructure and Deformation of Advanced Alloys)
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9 pages, 1598 KiB  
Article
General Trends in the Compression of Glasses and Liquids
by Oliver Tschauner
Crystals 2024, 14(9), 815; https://doi.org/10.3390/cryst14090815 - 17 Sep 2024
Viewed by 496
Abstract
The present work relates the isothermal volumes of silicate glasses and melts to the combined ionic volumes of their chemical constituents. The relation is an extension of a relation that has already been established for crystalline oxides, silicates, alumosilicates, and other materials that [...] Read more.
The present work relates the isothermal volumes of silicate glasses and melts to the combined ionic volumes of their chemical constituents. The relation is an extension of a relation that has already been established for crystalline oxides, silicates, alumosilicates, and other materials that have O2− as a constituent anion. The relation provides constraints on bond coordination, indicates pressure-induced changes in coordination in melts and glasses and interatomic distances, and quantifies the extent of transitory regions in pressure-induced coordination changes. Full article
(This article belongs to the Special Issue Pressure-Induced Phase Transformations (Third Edition))
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30 pages, 7196 KiB  
Article
The Counterion (SO42− and NO3−) Effect on Crystallographic, Quantum-Chemical, Protein-, and DNA-Binding Properties of Two Novel Copper(II)–Pyridoxal-Aminoguanidine Complexes
by Violeta Jevtovic, Luka Golubović, Odeh A. O. Alshammari, Munirah Sulaiman Alhar, Tahani Y. A. Alanazi, Violeta Rakic, Rakesh Ganguly, Jasmina Dimitrić Marković, Aleksandra Rakić and Dušan Dimić
Crystals 2024, 14(9), 814; https://doi.org/10.3390/cryst14090814 - 14 Sep 2024
Cited by 1 | Viewed by 681
Abstract
New Cu(II) complexes with pyridoxal-aminoguanidine (PLAG) ligands and different counterions (SO42− and NO3−) were prepared and their crystal structures were solved by the X-ray crystallography. The geometries of the obtained complexes significantly depended on the counterions, leading to [...] Read more.
New Cu(II) complexes with pyridoxal-aminoguanidine (PLAG) ligands and different counterions (SO42− and NO3−) were prepared and their crystal structures were solved by the X-ray crystallography. The geometries of the obtained complexes significantly depended on the counterions, leading to the square-pyramidal structure of [Cu(PLAG)NO3H2O]NO3 (complex 1) and square-planar structure of [Cu(PLAG)H2O]SO4 (complex 2). The intermolecular interactions were examined using the Hirshfeld surface analysis. The theoretical structures of these complexes were obtained by optimization at the B3LYP/6-311++G(d,p)(H,C,N,O,S)/LanL2DZ(Cu) level of theory. The Quantum Theory of Atoms in Molecules (QTAIM) was applied to assess the strength and type of the intramolecular interactions and the overall stability of the structures. The interactions between the complexes and transport proteins (human serum albumin (HSA)) and calf thymus DNA (CT-DNA) were examined by spectrofluorometric/spectrophotometric titration and molecular docking. The binding mechanism to DNA was assessed by potassium iodide quenching experiments. The importance of counterions for binding was shown by comparing the experimental and theoretical results and the examination of binding at the molecular level. Full article
(This article belongs to the Special Issue Synthesis, Crystal Structures and Hirshfeld Surface Analysis of Coordination Compounds (3rd Edition))
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17 pages, 11981 KiB  
Article
The Enamelled Tiles of Olite’s Castle (Spain): Characterization, Provenance, and Manufacture Technology
by Iván Ruiz-Ardanaz, Esther Lasheras and Adrián Durán
Crystals 2024, 14(9), 813; https://doi.org/10.3390/cryst14090813 - 14 Sep 2024
Viewed by 736
Abstract
The objective of this study was to determine the authorship, provenance, and technology of the mudejar enamelled tiles from the Olite Castle (northern Spain, 14th century). According to previous knowledge, Olite’s enamelled tiles had been manufactured in Manises (Valencia, Spain). The analysis of [...] Read more.
The objective of this study was to determine the authorship, provenance, and technology of the mudejar enamelled tiles from the Olite Castle (northern Spain, 14th century). According to previous knowledge, Olite’s enamelled tiles had been manufactured in Manises (Valencia, Spain). The analysis of ceramic pastes revealed the existence of two different chemical compositions, suggesting the use of two different clay sources, probably one from the Tudela area, and another from the Tafalla–Olite area. Those probably made in the Tudela area stood out with a higher diopside (CaMgSi2O6) content. Those probably made in the Tafalla–Olite area stood out for their calcium-bearing minerals, such as calcite (CaCO3) or gehlenite (Ca2Al(AlSi)O7). On this basis, production in Manises has been ruled out. However, it is highly probable that the artisans of Manises would have led the production from Tudela. The study of the firing temperatures and composition of the enamels indicated that the production methods and materials used in Tafalla–Olite (800–850 °C) and Tudela (higher than 900 °C) were different, reflecting the influence of local and Manises artisans, respectively. In Olite tiles, enamel was applied following recipes from the 14th and 15th centuries. Full article
(This article belongs to the Collection Topic Collection: Mineralogical Crystallography)
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9 pages, 4348 KiB  
Article
Surface Electronic Structure of Cr Doped Bi2Se3 Single Crystals
by Turgut Yilmaz, Xiao Tong, Zhongwei Dai, Jerzy T. Sadowski, Genda Gu, Kenya Shimada, Sooyeon Hwang, Kim Kisslinger, Elio Vescovo and Boris Sinkovic
Crystals 2024, 14(9), 812; https://doi.org/10.3390/cryst14090812 - 14 Sep 2024
Viewed by 637
Abstract
Here, by using angle-resolved photoemission spectroscopy, we showed that Bi2−xCrxSe3 single crystals have a distinctly well-defined band structure with a large bulk band gap and undistorted topological surface states. These spectral features are unlike their thin film forms [...] Read more.
Here, by using angle-resolved photoemission spectroscopy, we showed that Bi2−xCrxSe3 single crystals have a distinctly well-defined band structure with a large bulk band gap and undistorted topological surface states. These spectral features are unlike their thin film forms in which a large nonmagnetic gap with a distorted band structure was reported. We further provide laser-based high resolution photoemission data which reveal a Dirac point gap even in the pristine sample. The gap becomes more pronounced with Cr doping into the bulk of Bi2Se3. These observations show that the Dirac point can be modified by the magnetic impurities as well as the light source. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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17 pages, 7697 KiB  
Article
Single-Crystal Structure Analysis of Dicarboxamides: Impact of Heteroatoms on Hydrogen Bonding of Carboxamide Groups
by Abdulrahman Mohabbat, Jasmin Salama, Philipp Seiffert, István Boldog and Christoph Janiak
Crystals 2024, 14(9), 811; https://doi.org/10.3390/cryst14090811 - 14 Sep 2024
Viewed by 623
Abstract
This research examines how heteroatoms in a six- or five-membered pyridine, thiophene or furan ring spacer between two carboxamide groups influence the hydrogen bonding for advancements in supramolecular chemistry and drug development. The solvent-free crystal structures of 3,5-pyridinedicarboxamide (PDC), 2,5-thiophenedicarboxamide (TDC) and 2,5-furandicarboxamide [...] Read more.
This research examines how heteroatoms in a six- or five-membered pyridine, thiophene or furan ring spacer between two carboxamide groups influence the hydrogen bonding for advancements in supramolecular chemistry and drug development. The solvent-free crystal structures of 3,5-pyridinedicarboxamide (PDC), 2,5-thiophenedicarboxamide (TDC) and 2,5-furandicarboxamide (FDC-subl, crystallized by sublimation), and the monohydrate structure of FDC-solv (crystallized from methanol) are described with the hydrogen-bonding analyzed by the Etter graph-set notation. The carbon atoms of the amide groups form an angle of 121° in PDC, 151° in TDC, 137° in FDC-solv and 135° in FDC-subl with the ring centroid. Only in the structure of PDC does the heteroatom act as an H-bond acceptor as part of a C11(6) chain. In TDC and FDC, the heteroatoms do not interact with the amide -NH2 groups. Full article
(This article belongs to the Section Crystal Engineering)
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15 pages, 5307 KiB  
Essay
Pulsed Laser Polishing of Zirconia Ceramic Microcrack Generation Mechanism and Size Characterization Study
by Zhanwang Zhou, Zhenyu Zhao, Jin He and Ruikang Shi
Crystals 2024, 14(9), 810; https://doi.org/10.3390/cryst14090810 - 13 Sep 2024
Viewed by 480
Abstract
In order to study the mechanism of microcrack generation in the process of pulsed laser polishing of zirconia ceramics and the influence of laser polishing process parameters on the surface temperature and surface stress, this paper establishes a finite element computational model of [...] Read more.
In order to study the mechanism of microcrack generation in the process of pulsed laser polishing of zirconia ceramics and the influence of laser polishing process parameters on the surface temperature and surface stress, this paper establishes a finite element computational model of pulsed laser polishing of zirconia ceramics based on the COMSOL Multiphysics multi-physics field simulation software. Firstly, in the process of establishing the finite element model, the temperature field and stress field coupling is used to analyze the temperature field and stress field changes during the laser polishing process, which reveals the microcrack generation mechanism and size characteristics of zirconia ceramics in the process of pulsed laser polishing. Secondly, through parameterized scanning, the variation rules of surface temperature and surface stress were studied under different process parameters of laser power, scanning speed, pulse frequency and pulse width. Finally, the validity of the finite element calculation model is verified by the pulsed laser polishing zirconia ceramics experiment. The results show that, in a certain energy range, the high-energy laser beam can effectively reduce the surface roughness of the material, and with the increase in the time of laser action on the surface layer of the material, it will cause the temperature and thermal stress of the surface layer of the material to continue to accumulate, and when the stress value exceeds the yield limit of the material, cracks will form in the surface layer of the material; because the laser power, scanning speed, pulse frequency and pulse width are used to affect the laser energy density, and then, the pulse width will be affected by the process parameters of the laser energy density, and thus the surface temperature and thermal stress of the surface layer of the material. Because the laser power, scanning speed, pulse frequency and pulse width all affect the thermal stress on the material surface by influencing the laser energy density acting on the material surface, the laser energy density is the main influencing factor of the dimensional characteristics of the microcracks. In addition, the microcrack width and depth will increase when the laser energy density acting on the material surface layer increases. Full article
(This article belongs to the Section Polycrystalline Ceramics)
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15 pages, 51500 KiB  
Article
The Effects of Laser Parameters on the Wear Resistance of a Cu/BN Remelted Layer
by Hengzheng Li, Shuai Chen, Yang Chen, Yan Liu, Zichen Tao, Yinghe Qin and Conghu Liu
Crystals 2024, 14(9), 809; https://doi.org/10.3390/cryst14090809 - 13 Sep 2024
Viewed by 510
Abstract
In order to improve the wear resistance of copper and enhance the surface properties of copper parts, this article uses BN nanoparticles as a reinforcing phase and the laser remelting method to prepare a Cu/BN remelted layer on the copper surface. The surface [...] Read more.
In order to improve the wear resistance of copper and enhance the surface properties of copper parts, this article uses BN nanoparticles as a reinforcing phase and the laser remelting method to prepare a Cu/BN remelted layer on the copper surface. The surface morphology, crystal structure, microhardness, and wear resistance of the samples were tested and characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), a microhardness tester, and a friction and wear tester. The effects of laser frequency, pulse width, and energy density on the surface morphology and wear resistance of the samples were analyzed and studied, and the effects of the laser parameters on the properties of the Cu/BN remelted layer were discussed. The research results indicate that laser frequency, pulse width, and energy density have a direct impact on the surface morphology and properties of the Cu/BN remelted layer, but the impact mechanism by the above parameters on the remelted layer is different. The effects of laser frequency on the remelted layer are caused by changes in the overlap mode of the remelting points, while laser pulse width and energy density are achieved through changes in remelting intensity. When the laser frequency is 10 Hz, the pulse width is 10 ms, and the energy density is 165.8 J/mm2, the Cu/BN remelted layer has better surface properties. Full article
(This article belongs to the Special Issue Microstructural Characterization and Property Analysis of Alloys)
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16 pages, 5383 KiB  
Article
Enhanced Corrosion Resistance of CuAl/BN Coatings through the Addition of Rare Earth Elements and High-Temperature Oxidation Treatment
by Yongjun Liu, Chuanbing Huang, Hao Yang, Xiaoming Sun, Huifeng Zhang, Yonghui Sun, Weigang Zhang, Hao Lan and Shouquan Yu
Crystals 2024, 14(9), 808; https://doi.org/10.3390/cryst14090808 - 12 Sep 2024
Viewed by 684
Abstract
Abradable seal coatings represent a critical technology within the realm of advanced power systems, designed to minimize airflow channel leakage, thereby reducing energy consumption and enhancing overall efficiency. In the present study, CuAl/BN, CuAlLaF3/BN, and CuAlY/BN abradable seal coatings were prepared [...] Read more.
Abradable seal coatings represent a critical technology within the realm of advanced power systems, designed to minimize airflow channel leakage, thereby reducing energy consumption and enhancing overall efficiency. In the present study, CuAl/BN, CuAlLaF3/BN, and CuAlY/BN abradable seal coatings were prepared using plasma spraying technology. Both the as-deposited coatings and high-temperature oxidation-treated coatings were comprehensively investigated by means of scanning electron microscopy (SEM), open-circuit potentials (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), salt-spray corrosion testing, and bond strength evaluations. The results show that the addition of rare earth elements to the CuAl/BN coatings does not enhance the corrosion resistance of the coatings and even leads to a decrease in the corrosion resistance of the coatings. In contrast, the CuAlY/BN coatings exhibited a significant improvement in corrosion resistance following an oxidation treatment at 550 °C. This enhancement is attributed to the yttrium (Y) element, which facilitates the formation of passivation films and confers a resistance effect, thereby bolstering the coatings’ resistance to corrosion. The bond strength of the high-temperature oxidation-treated CuAlY/BN coating was improved by about 30% after 960 h of salt-spray corrosion. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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14 pages, 7324 KiB  
Article
Kinetic Phase Behavior of Binary Mixtures of Tri-Saturated Triacylglycerols Containing Lauric Acid
by Sabine Danthine
Crystals 2024, 14(9), 807; https://doi.org/10.3390/cryst14090807 - 12 Sep 2024
Viewed by 534
Abstract
Describing fat phase behavior is of significant interest for food and non-food applications. One recognized approach to understand the behavior of complex fatty systems is to simplify the fat matrix and to emphasize only the main triacylglycerol (TAG) components. In this context, the [...] Read more.
Describing fat phase behavior is of significant interest for food and non-food applications. One recognized approach to understand the behavior of complex fatty systems is to simplify the fat matrix and to emphasize only the main triacylglycerol (TAG) components. In this context, the kinetic phase behavior and phase transformation paths of binary mixtures of selected saturated monoacids (trilaurin (LaLaLa), trimyristin (MMM), and tripalmitin (PPP)) and of mixed saturated triacylglycerols containing lauric (La) and myristic (M) acids (MMLa and LaLaM) typical from lauric fats were investigated. Kinetic phase diagrams were constructed based on DSC heating thermograms (fast cooling and reheating at 5 °C min−1) and powder X-ray diffraction data. The investigated binary kinetic phase diagram presented an apparently typical eutectic behavior, with a eutectic point that varies depending on the blend composition. Introducing mixed saturated TAGs (MMLa or LaLaM) in binary blends led to a shift in the position of the eutectic point. Considering the binary blends made of LaLaLa, it was shifted from XLaLaLa = 0.7 in the LaLaLa–MMM system to XLaLaLa = 0.5 for the LaLaLa–MMLa mixture, and to XLaLaLa = 0.25 for the LaLaLa–LaLaM blend. Finally, the blend made of the two mixed TAGs (MMLa–LaLaM) also presented a complex non-ideal behavior. Full article
(This article belongs to the Section Industrial Crystallization)
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28 pages, 11529 KiB  
Review
Ferroelectric/Piezoelectric Materials in Energy Harvesting: Physical Properties and Current Status of Applications
by Maria-Argyro Karageorgou, Kosmas Tsakmakidis and Dimosthenis Stamopoulos
Crystals 2024, 14(9), 806; https://doi.org/10.3390/cryst14090806 - 12 Sep 2024
Viewed by 1356
Abstract
The inevitable feedback between the environmental and energy crisis within the next decades can probably trigger and/or promote a global imbalance in both financial and public health terms. To handle this difficult situation, in the last decades, many different classes of materials have [...] Read more.
The inevitable feedback between the environmental and energy crisis within the next decades can probably trigger and/or promote a global imbalance in both financial and public health terms. To handle this difficult situation, in the last decades, many different classes of materials have been recruited to assist in the management, production, and storage of so-called clean energy. Probably, ferromagnets, superconductors and ferroelectric/piezoelectric materials stand at the frontline of applications that relate to clean energy. For instance, ferromagnets are usually employed in wind turbines, superconductors are commonly used in storage facilities and ferroelectric/piezoelectric materials are employed for the harvesting of stray energy from the ambient environment. In this work, we focus on the wide family of ferroelectric/piezoelectric materials, reviewing their physical properties in close connection to their application in the field of clean energy. Among other compounds, we focus on the archetypal compound Pb(Zr,Ti)O3 (or PZT), which is well studied and thus preferred for its reliable performance in applications. Also, we pay special attention to the advanced ferroelectric relaxor compound (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 (or PMN-xPT) due to its superior performance. The inhomogeneous composition that many kinds of such materials exhibit at the so-called morphotropic phase boundary is reviewed in connection to possible advantages that it may bring when applications are considered. Full article
(This article belongs to the Section Materials for Energy Applications)
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3 pages, 168 KiB  
Editorial
Advances in Pharmaceutical Crystals: Control over Nucleation and Polymorphism
by Fiora Artusio, Rafael Contreras-Montoya and José A. Gavira
Crystals 2024, 14(9), 805; https://doi.org/10.3390/cryst14090805 - 12 Sep 2024
Cited by 1 | Viewed by 701
Abstract
The Special Issue “Advances in Pharmaceutical Crystals: Control over Nucleation and Polymorphism” collects eight papers focusing on different aspects of crystallization processes for pharmaceuticals [...] Full article
(This article belongs to the Special Issue Advances in Pharmaceutical Crystals: Control over Nucleation and Polymorphism)
16 pages, 9738 KiB  
Article
Spectral Characteristics of Nitrogen-Doped CVD Synthetic Diamonds and the Origin of Surface Blue Fluorescence
by Yu Zhang, Guanghai Shi and Zixuan Xie
Crystals 2024, 14(9), 804; https://doi.org/10.3390/cryst14090804 - 11 Sep 2024
Viewed by 685
Abstract
In recent years, many studies have been published on CVD diamond growth, but the reason for the irregular blue surface fluorescence of CVD diamond under ultra-deep UV radiation (i.e., under DiamondView) is still unclear. Here, a batch of as-grown and LPHT-annealed CVD synthetic [...] Read more.
In recent years, many studies have been published on CVD diamond growth, but the reason for the irregular blue surface fluorescence of CVD diamond under ultra-deep UV radiation (i.e., under DiamondView) is still unclear. Here, a batch of as-grown and LPHT-annealed CVD synthetic diamond samples from a Chinese company in Zhejiang were analyzed for the various spectral (infrared (IR), UV–visible absorption, Raman, and photoluminescence (PL)) characteristics to explore the origin of surface blue fluorescence. The results show that the samples are nitrogen-doped type IIa CVD synthetic diamonds. Spectral peaks of the earlier CVD products, e.g., 3123 cm−1 (NVH0) (IR absorption spectrum) and 596/597 nm (PL emission spectrum), are absent in these samples, while the peaks at 736.5/736.8 nm (SiV−) in the UV or PL spectra are less common. PL spectra and DiamondView fluorescence indicate that the samples have generally strong luminescence peaks at 637 nm in the NV− center, 575 nm in the NV0 center, and other luminescence peaks caused by nitrogen-related defects. The as-grown samples observed under DiamondView show orange-red fluorescence accompanied by striations due to step-flow growth, and blue fluorescence appears as irregular threads or bundles on the surface. The LPHT-annealed sample shows weaker fluorescence with localized patches of green fluorescence contributed by weak H3 centers. The micro-IR spectra suggest that the unique blue fluorescence in the CVD diamond may be related to the dislocations caused by sp3-CH2 due to the incomplete dehydrogenation of hydrocarbon groups in the raw material. Full article
(This article belongs to the Special Issue The Progress of In-Situ Study of Mineralogy and Gemmology)
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14 pages, 23510 KiB  
Article
Experimental Study of Reaming Sizes on Fatigue Life of Cold-Expanded 7050-T7451 Aluminum Alloy
by Muyu Guan, Qichao Xue, Zixin Zhuang, Quansheng Hu and Hui Qi
Crystals 2024, 14(9), 803; https://doi.org/10.3390/cryst14090803 - 11 Sep 2024
Viewed by 515
Abstract
The split-sleeve cold expansion technology is widely used in the aerospace industry, particularly for fastening holes, to enhance the fatigue life of components. However, to ensure proper assembly and improve surface integrity, reaming of the cold-expanded holes is necessary. This study investigates the [...] Read more.
The split-sleeve cold expansion technology is widely used in the aerospace industry, particularly for fastening holes, to enhance the fatigue life of components. However, to ensure proper assembly and improve surface integrity, reaming of the cold-expanded holes is necessary. This study investigates the effects of cold expansion and reaming processes on the fatigue performance of 7050-T7451 aluminum alloy. Fatigue tests, residual stress measurements, and microstructural analyses of the hole edges were conducted on specimens with four different hole diameters after cold expansion and reaming. It was found that the depth of reaming significantly affects fatigue life. During the cold expansion process, the compressive residual stress formed around the hole effectively improves fatigue performance. The experiments demonstrated that reaming by 0.2 mm to 0.4 mm helps eliminate minor defects, thereby improving fatigue life. However, reaming beyond 0.5 mm may lead to stress relief and the removal of dense grains at the hole edges, reducing fatigue life. Therefore, determining the optimal reaming size is crucial for enhancing the reliability of aerospace fasteners. Full article
(This article belongs to the Special Issue Design, Development and Processing of Aluminium Alloys and Their Composite Materials)
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13 pages, 6344 KiB  
Article
Defect Passivation for Highly Efficient and Stable Sn-Pb Perovskite Solar Cells
by Tengteng Li, Fupeng Ma, Yafeng Hao, Huijia Wu, Pu Zhu, Ziwei Li, Fengchao Li, Jiangang Yu, Meihong Liu, Cheng Lei and Ting Liang
Crystals 2024, 14(9), 802; https://doi.org/10.3390/cryst14090802 - 11 Sep 2024
Viewed by 792
Abstract
Sn-Pb perovskite solar cells, which have the advantages of low toxicity and a simple preparation process, have witnessed rapid development in recent years, with the power conversion efficiency for single-junction solar cells exceeding 23%. Nevertheless, the problems of poor crystalline quality of Sn-Pb [...] Read more.
Sn-Pb perovskite solar cells, which have the advantages of low toxicity and a simple preparation process, have witnessed rapid development in recent years, with the power conversion efficiency for single-junction solar cells exceeding 23%. Nevertheless, the problems of poor crystalline quality of Sn-Pb perovskite films arising from rapid crystallization rate and facile oxidation of Sn2+ to Sn4+ have become key issues for the further development of Sn-Pb perovskite solar cells. Herein, we report the incorporation of triazinamide (N-(6-methyl-3-oxo-2,5-dihydro-1,2,4-Triazin-4(3H)-YL) acetamide) as an additive to regulate the crystalline growth of Sn-Pb perovskite films, resulting in films with low trap density and large grain size. The triazinamide additive effectively passivated defects in the perovskite films. As a result, the triazinamide-modified perovskite solar cells achieved a higher efficiency of 15.73%, compared with 13.32% for the control device, significantly improving device performance. Notably, the optimal triazinamide-modified perovskite solar cell maintained 72% of its initial power conversion efficiency after being stored in an air environment for nearly 300 h, while only 18% of the power conversion efficiency of the control perovskite solar cell was retained. This study proposes an effective strategy for fabricating highly efficient and stable Sn-Pb perovskite solar cells. Full article
(This article belongs to the Special Issue New Insights into Perovskite Materials: From Fundamental Science to Applications)
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35 pages, 14744 KiB  
Review
Review of the Properties of GaN, InN, and Their Alloys Obtained in Cubic Phase on MgO Substrates by Plasma-Enhanced Molecular Beam Epitaxy
by Edgar López Luna and Miguel Ángel Vidal
Crystals 2024, 14(9), 801; https://doi.org/10.3390/cryst14090801 - 11 Sep 2024
Viewed by 1271
Abstract
Gallium nitride (GaN) semiconductors and their broadband InGaN alloys in their hexagonal phase have been extensively studied over the past 30 years and have allowed the development of blue-ray lasers, which are essential disruptive developments. In addition to high-efficiency white light-emitting diodes, which [...] Read more.
Gallium nitride (GaN) semiconductors and their broadband InGaN alloys in their hexagonal phase have been extensively studied over the past 30 years and have allowed the development of blue-ray lasers, which are essential disruptive developments. In addition to high-efficiency white light-emitting diodes, which have revolutionized lighting technologies and generated a great industry around these semiconductors, several transistors have been developed that take advantage of the characteristics of these semiconductors. These include power transistors for high-frequency applications and high-power transistors for power electronics, among other devices, which have far superior achievements. However, less effort has been devoted to studying GaN and InGaN alloys grown in the cubic phase. The metastable or cubic phase of III-N alloys has superior characteristics compared to the hexagonal phase, mainly because of the excellent symmetry. It can be used to improve lighting technologies and develop other devices. Indium gallium nitride, InxGa1−xN alloy, has a variable band interval of 0.7 to 3.4 eV that covers almost the entire solar spectrum, making it a suitable material for increasing the efficiencies of photovoltaic devices. In this study, we successfully synthesized high-quality cubic InGaN films on MgO (100) substrates using plasma-assisted molecular beam epitaxy (PAMBE), demonstrating tunable emissions across the visible spectrum by varying the indium concentration. We significantly reduced the defect density and enhanced the crystalline quality by using an intermediate cubic GaN buffer layer. We not only developed a heterostructure with four GaN/InGaN/GaN quantum wells, achieving violet, blue, yellow, and red emissions, but also highlighted the immense potential of cubic InGaN films for high-efficiency light-emitting diodes and photovoltaic devices. Achieving better p-type doping levels is crucial for realizing diodes with excellent performance, and our findings will pave the way for this advancement. Full article
(This article belongs to the Special Issue Reviews of Crystal Engineering)
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48 pages, 7039 KiB  
Review
A Review of Nanocarbon-Based Anode Materials for Lithium-Ion Batteries
by Nagaraj Nandihalli
Crystals 2024, 14(9), 800; https://doi.org/10.3390/cryst14090800 - 10 Sep 2024
Cited by 1 | Viewed by 2143
Abstract
Renewable and non-renewable energy harvesting and its storage are important components of our everyday economic processes. Lithium-ion batteries (LIBs), with their rechargeable features, high open-circuit voltage, and potential large energy capacities, are one of the ideal alternatives for addressing that endeavor. Despite their [...] Read more.
Renewable and non-renewable energy harvesting and its storage are important components of our everyday economic processes. Lithium-ion batteries (LIBs), with their rechargeable features, high open-circuit voltage, and potential large energy capacities, are one of the ideal alternatives for addressing that endeavor. Despite their widespread use, improving LIBs’ performance, such as increasing energy density demand, stability, and safety, remains a significant problem. The anode is an important component in LIBs and determines battery performance. To achieve high-performance batteries, anode subsystems must have a high capacity for ion intercalation/adsorption, high efficiency during charging and discharging operations, minimal reactivity to the electrolyte, excellent cyclability, and non-toxic operation. Group IV elements (Si, Ge, and Sn), transition-metal oxides, nitrides, sulfides, and transition-metal carbonates have all been tested as LIB anode materials. However, these materials have low rate capability due to weak conductivity, dismal cyclability, and fast capacity fading owing to large volume expansion and severe electrode collapse during the cycle operations. Contrarily, carbon nanostructures (1D, 2D, and 3D) have the potential to be employed as anode materials for LIBs due to their large buffer space and Li-ion conductivity. However, their capacity is limited. Blending these two material types to create a conductive and flexible carbon supporting nanocomposite framework as an anode material for LIBs is regarded as one of the most beneficial techniques for improving stability, conductivity, and capacity. This review begins with a quick overview of LIB operations and performance measurement indexes. It then examines the recently reported synthesis methods of carbon-based nanostructured materials and the effects of their properties on high-performance anode materials for LIBs. These include composites made of 1D, 2D, and 3D nanocarbon structures and much higher Li storage-capacity nanostructured compounds (metals, transitional metal oxides, transition-metal sulfides, and other inorganic materials). The strategies employed to improve anode performance by leveraging the intrinsic features of individual constituents and their structural designs are examined. The review concludes with a summary and an outlook for future advancements in this research field. Full article
(This article belongs to the Special Issue The Development of Advanced Materials for Electrochemical Energy Conversion and Storage)
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12 pages, 2763 KiB  
Article
Terahertz Modulation Properties Based on ReS2/Si Heterojunction Films
by Xunjun He, Han Xu, Hongyuan Liu, Jia Nie and Guangjun Lu
Crystals 2024, 14(9), 799; https://doi.org/10.3390/cryst14090799 - 10 Sep 2024
Viewed by 514
Abstract
Low cost, low power consumption and high performance are urgent needs for the application of terahertz modulation devices in the 6G field. Rhenium disulfide (ReS2) is one of the ideal candidate materials due to its unique direct band gap, but it [...] Read more.
Low cost, low power consumption and high performance are urgent needs for the application of terahertz modulation devices in the 6G field. Rhenium disulfide (ReS2) is one of the ideal candidate materials due to its unique direct band gap, but it lacks in-depth research. In this work, a highly stable ReS2 nanodispersion was prepared by liquid-phase exfoliation, and a uniform, dense and well-crystallized ReS2 film was prepared on high-resistivity silicon by drop casting. The morphological, optical and structural properties of the ReS2/Si heterojunction film were characterized by OM, SEM, AFM, XRD, RS and PL. The terahertz performance was tested by using a homemade THz-TDS instrument, and the influence of different laser wavelengths and powers on the terahertz modulation performance of the sample was analyzed. The modulation depth of the sample was calculated based on the transmission curve, and the changes in the refractive index and conductivity of the sample with frequency at the corresponding laser power were calculated. The results show that the fabricated ReS2/Si heterojunction terahertz modulator can stably achieve 30% broadband modulation in the range of 0.3~1.5 THz under the low-power pumping of 1555 mW/cm2, and the maximum conductivity is 3.8 Ω−1m−1. Full article
(This article belongs to the Special Issue Advanced Research in 2D Materials)
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