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With the rapid advancement of optical communication technology and integrated electronic devices, magneto-optical thin films, particularly rare earth iron garnet (RIG), have emerged as the most promising materials for near-infrared communication windows in recent years. In order to minimize the impact on the related properties of magneto-optical thin films during the preparation process, it's important to select the substrate materials. Silicon and garnet oxides are commonly used as substrates for the preparation of RIG magneto-optical thin films. The lattice constant of RIG magneto-optical thin films is generally around 12. 4 Å, and gallium-containing garnet oxide single crystal substrates have a similar lattice constant, which shows large lattice constant characteristics, making them one of the suitable substrate materials. However, the raw material gallium oxide is volatile at high temperature, the preparation of gallium-containing garnet single crystal has been a hot topic. The further study of gallium garnet series substrate single crystals is expected to promote the development of a new magnetooptical devices. In this paper, we reviewed the research of gallium garnet series single crystal, summarized the work of our team in the growth, structure and key parameters of these crystals, and outlooked the trend of research and development. [ABSTRACT FROM AUTHOR]

Mg-Y-Zn-Al alloys processed by the rapidly solidified ribbon consolidation (RSRC) technique are candidate materials for structural applications due to their improved mechanical performance. Their outstanding mechanical strength is attributed to solute-enriched stacking faults (SESFs), which can form cluster-arranged layers (CALs) and cluster-arranged nanoplates (CANaPs) or complete the long-period stacking ordered (LPSO) phase. The thermal stability of these solute arrangements strongly influences mechanical performance at elevated temperatures. In this study, an RSRC-processed Mg—0.9%, Zn—2.05%, Y—0.15% Al (at%) alloy was heated at a rate of 0.666 K/s up to 833 K, a temperature very close to melting point. During annealing, in situ X-ray diffraction (XRD) measurements were performed using synchrotron radiation in order to monitor changes in the structure. These in situ XRD experiments were completed with ex situ electron microscopy investigations before and after annealing. At 753 K and above, the ratio of the matrix lattice constants, c/a, decreased considerably, which was restored during cooling. This decrease in c/a could be attributed to partial melting in the volumes with high solute contents, causing a change in the chemical composition of the remaining solid material. In addition, the XRD intensity of the secondary phase increased at the beginning of cooling and then remained unchanged, which was attributed to a long-range ordering of the solute-enriched phase. Both the matrix grains and the solute-enriched particles were coarsened during the heat treatment, as revealed by electron microscopy. [ABSTRACT FROM AUTHOR]

Ti-V-based alloys are proved of huge potential in storing hydrogen, but the incomplete reversible hydrogen storage capacity caused by overstability of V hydride has limited the large-scale application. In this study, Ti32V40+xFe23-xMn5 (x=0, 4, 8, 12, at.%) alloys were designed, and the effects of V/Fe ratio on phase constitution and hydrogen storage properties were investigated. The main phase of the alloys is body-centered cubic (BCC) phase, and the lattice constants of the BCC phase decrease with the decrease of V/Fe ratio. Moreover, C14 Laves phase exists in alloys with a Fe content of 19at.% to 23at.%. For hydrogenation, the C14 Laves phase can accelerate the hydrogen absorption rate, but the hydrogen absorption capacity is reduced. With the decrease of V/Fe ratio, the hydride gradually destabilizes. Owing to its large lattice constant and high hydrogen absorption phase content, the Ti32V52Fe11Mn5 alloy shows the most enhanced hydrogen storage properties with hydrogenation and dehydrogenation capacities of 3.588wt.% at 298 K and 1.688wt.% at 343 K, respectively. The hydrogen absorption capacity of this alloy can be reserved to 3.574wt.% after 20 cycles of hydrogen absorption and desorption. [ABSTRACT FROM AUTHOR]

In this study, a series of Ti50–ZrVNbCr alloys were designed under with the constant atomic radius mismatch. It was suggested that valence electron concentration (VEC) and lattice constant, which evolve oppositely in the series of the Ti50–ZrVNbCr alloys, jointly influence the mechanical properties. Based on modeling, the evolution of ductility and yield strength of the designed alloys was predicted. Ductility was predicted to be superior in the VEC range from 4.22 to 4.25, with the lattice constant correspondently ranging from 3.340 Å to 3.334 Å. The optimization of strength-ductility synergy was discussed in terms of coordinately adjusting VEC and lattice constant. The experimental results were quite consistent with the prediction results, showing that the alloy with the VEC value of 4.25 and the lattice constant of 3.334 Å, which consisted of 50 at.%Ti, 28.1 at.%Zr, 9.4 at.%V, 9.4 at.%Nb, and 3.1 at.%Cr, possessed the best ductility and superior strength-ductility synergy.

This study explores highly efficient waveguide detectors for Si/SiGe lasers utilizing Si1-x-y GexCy. By precisely tailoring properties such as temperature, structure, composition, thickness, and doping, we aim to reduce light losses and improve performance by increasing light overlap with the active region. This approach overcomes Si/SiGe lattice mismatch limitations, especially in medium and high germanium SiGe. Incorporating carbon (C) into Si1-x-y GexCy enables perfect light detection and improved confinement, addressing a major challenge in diode lasers. The proposed detector design comprises an active zone sandwiched between lightly doped silicon layers (Si(n) and Si(p)) and heavily doped confinement layers (Si1- xGex (n+) and Si1-xGex (p+)). We study three Si1-x-y GexCycompositions (Si0.675Ge0.3C0.025, Si0.74Ge0.25- C0.01 and Si0.79Ge0.2C0.01) with absorption wavelengths of 1.42 µm, 1.35 µm, and 1.29 µm, respectively, and active layer thicknesses ranging from 150-600 nm. For each design, we propose an optimized waveguide structure with appropriate doping. [ABSTRACT FROM AUTHOR]

Perovskite manganites have been widely studied due to their rich magnetic and electrical properties, such as the colossal magnetoresistance (CMR) effect, ferromagnetic transition, and exchange bias effect. This work reports the preparation of five [La0.8Ca0.2MnO3/La0.5Ca0.5MnO3]20 superlattice films with different La0.8Ca0.2MnO3 layer thicknesses on (001) LaAlO3 substrate using pulsed laser deposition technology. The thickness of the La0.5Ca0.5MnO3 sublayers for all five superlattice films during one growth cycle is 48 Å. The thickness of the La0.8Ca0.2MnO3 sublayers in the superlattice films during one growth cycle is 24 Å, 48 Å, 72 Å, 96 Å, and 120 Å, designated as SL-24, SL-48, SL-72, SL-96, and SL-120, respectively. The crystal structure (lattice constants) of samples is obtained using x-ray diffraction technology, and the strain states of the samples are determined based on the lattice constant. Three superlattice samples (SL-48, SL-72, and SL-96) are in a state of strain relaxation. The SL-24 and SL-120 samples are in a strain state, which is the result of the interlayer strain effect due to the asymmetric thickness of the two components between the sublayers. The magnetic properties of samples are analyzed based on the stress state and magnetic properties. All superlattice samples show a ferromagnetism-to-paramagnetism transition, and with the increase in the thickness of the La0.8Ca0.2MnO3 sublayer, the Curie temperature (TC) shows a gradual decreasing trend. In addition to the ferromagnetic phase transition in SL-96, the presence of the Néel temperature (representing antiferromagnetic phase transition) is also observed, further indicating that the magnetic performance is affected by factors in addition to strain, such as multiple magnetic phases. There is no significant exchange bias in SL-48, SL-72, and SL-96, since the percolation of ferromagnetic clusters at the interface of ferromagnetic La0.8Ca0.2MnO3 and charge-ordered antiferromagnetic La0.5Ca0.5MnO3 in superlattices destroys the exchange coupling between ferromagnetic and antiferromagnetic layers, resulting in a very small exchange bias. On the contrary, for the SL-24 and SL-120 samples with significant strain states, the strain can suppress the percolation behaviors at the interfaces of the ferromagnetic and antiferromagnetic layers, leading to a pronounced exchange bias effect. [ABSTRACT FROM AUTHOR]

GaBixSb1−x has been considered as a technologically important III–V semiconductor alloy for its potential applications in mid-infrared and near-infrared devices. So far, we still know little about the properties of the Sb-rich GaBixSb1−x. In order to better understand it, first-principles calculations have been performed. A more accurate lattice constant of GaBi has been obtained in this work, and its value was 6.275 Å. After fitting the calculated lattice constant of GaBixSb1−x, it yields b = 0.011 Å. Based on the band structures and the partial densities of states of GaBixSb1−x, it has been found that the initial Bi level lies 1.0 eV below the valence band maximum (VBM) of GaSb at the G point. It has also been found that the highly localized Ga-3d peak can be used to ascertain the valence band offset between GaSb and GaBi. According to the location of the localized Ga-3d peak, the valence band offset between GaSb and GaBi was 0.42 eV. In addition, the direct band gap energy in the Sb-rich range decreases quickly due to the rise of the VBM and the decline of the conduction band minimum. For the sake of describing the band gap energy, a combination of a linear equation and the fusion-repelling model is proposed. [ABSTRACT FROM AUTHOR]

The high stability of hydride phase has limited the improvement for the hydrogen storage properties of Ti–V based alloy at room temperatures. In this work, the stability of hydride was reduced by designing a low-price Ti–V–Fe–Mn alloy, and the effect of Ti/V ratio on the crystal structure and hydrogen storage properties was systematically investigated. The Ti 40- x V 40+ x Fe 15 Mn 5 (x = 0, 2, 4, 6, 8) alloys were synthesized using arc melting, and the as-prepared alloys are all composed of single BCC phase. The lattice constant and cell volume decrease linearly with a lessening in Ti/V ratio. The reduction of cell volume makes it difficult for hydrogen atoms to diffuse, resulting in a sluggish hydrogen absorption rate. The dehydrogenation plateau in PCI curve rises and corresponding thermodynamics is optimized with a decrease in the lattice constant, and the hydrogen atoms are more readily to release, especially for Ti 32 V 48 Fe 15 Mn 5 alloy with the dehydrogenation capacity of 1.83 wt% at 373 K. The result indicates the thermodynamic properties can be optimized by adjusting the lattice constant of Ti–V–Fe–Mn alloys, and hydrogen storage capacity is improved effectively. This study provides a reference for composition design of Ti–V–Fe–Mn alloys for high-density hydrogen storage. [Display omitted] • The solubility of iron for Ti–V based alloy is not less than 15 mol.%. • The Samples can absorb hydrogen after heat preservation at 623 K and 3 MPa H 2. • The substitution of V for Ti enhances the desorption capacity. [ABSTRACT FROM AUTHOR]

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Nickel ferrite solid solutions remain one of the main materials for a whole range of applications, including microwave equipment and components, the requirements for parameters and homogeneity of materials are constantly increasing. In this work, Ni1–xZnxFe2O4 nanoparticles with an average diameter of 12.5 nm were successfully synthesized by the microwave-assisted urea method. The temperature of a single-phase product formation was 400 °C, which is lower compared to more common precipitation from aqueous solution methods or solid-state route. Ni1–xZnxFe2O4 materials demonstrate high saturation magnetization and low coercive force. The magnetization changes with increasing Zn concentration and reaches the maximum at x = 0.5. Also, the increase in zinc content leads to an increase in the lattice parameters. The average size of ferrite nanoparticles synthesized by the microwave-assisted urea method is smaller compared to ferrites synthesized earlier by the co-precipitation method. Also, lower treatment temperatures provide higher stoichiometry, and homogeneity of materials while magnetization difference is negligible. These research results provide a general and effective route to synthesize other nanostructures for a variety of microwave components. [ABSTRACT FROM AUTHOR]

The Co0.8–xMgxZn0.2Fe2O4 (x = 0.00 to 0.56) ferrites were prepared by solid state reaction route. The phase composition and morphology of the synthesized ferrites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. From the XRD results, single phase cubic spinal structure with space group Fd-3m was confirmed. The lattice constant (a), particle size (D), hopping lengths (LA and LB), bond lengths (A–O and B–O), ionic radii (rA and rB), microstrain (ε,) and dislocation density (ρD) were reported. The lattice constant increased as magnesium additive increased. The SEM image affirmed size and shape of particles. Crystallite size and microstrain were realized by W–H plot and SSP. [ABSTRACT FROM AUTHOR]

High entropy alloys (HEAs) were first reported in the early 2000s. High mixing entropy of the HEAs makes it present good thermal stability. Meanwhile, the large lattice distortion in the HEAs leads to significant solution strengthening. Additionally, cluster structures are formed within grains due to the large negative enthalpy. Consequently, the movement of dislocation is effectively hindered, and the strength of the HEAs is remarkably improved. Given to these unique characteristics, the HEAs is expected to have excellent physical and chemical properties at low and high temperatures. As a result, the HEAs have become a hot area with lots of published research papers. Based on existing physical and mechanical properties of the HEAs with BCC and FCC structure, relation among electron concentration, lattice constant, atomic mismatch, mixing enthalpy, hardness, elasticity modulus and normalized hardness were analyzed to develop a formula calculating elasticity modulus and hardness of the HEAs. On this basis, the composition design method of the HEAs with BCC and FCC structures is established by considering density, ductility and working environment. Finally, it is pointed out that the persistent strength of HEAs, the uniformity of composition and properties of large-sized ingots, and the preparation of large-sized alloy ingots are key issues that need to be addressed in the engineering application of HEAs.

Mg-Y-Zn-Al alloys processed by the rapidly solidified ribbon consolidation (RSRC) technique are candidate materials for structural applications due to their improved mechanical performance. Their outstanding mechanical strength is attributed to solute-enriched stacking faults (SESFs), which can form cluster-arranged layers (CALs) and cluster-arranged nanoplates (CANaPs) or complete the long-period stacking ordered (LPSO) phase. The thermal stability of these solute arrangements strongly influences mechanical performance at elevated temperatures. In this study, an RSRC-processed Mg—0.9%, Zn—2.05%, Y—0.15% Al (at%) alloy was heated at a rate of 0.666 K/s up to 833 K, a temperature very close to melting point. During annealing, in situ X-ray diffraction (XRD) measurements were performed using synchrotron radiation in order to monitor changes in the structure. These in situ XRD experiments were completed with ex situ electron microscopy investigations before and after annealing. At 753 K and above, the ratio of the matrix lattice constants, c/a, decreased considerably, which was restored during cooling. This decrease in c/a could be attributed to partial melting in the volumes with high solute contents, causing a change in the chemical composition of the remaining solid material. In addition, the XRD intensity of the secondary phase increased at the beginning of cooling and then remained unchanged, which was attributed to a long-range ordering of the solute-enriched phase. Both the matrix grains and the solute-enriched particles were coarsened during the heat treatment, as revealed by electron microscopy.

The mixed-valence perovskite manganites attracted much attention because of their interesting electro-magnetic properties, and strain modulation on magnetic properties of perovskite manganites is worth exploring. In this paper, [La 0. 8 Ca 0. 2 MnO3/La 0. 5 Ca 0. 5 MnO3] 2 0 superlattice films with different La 0. 8 Ca 0. 2 MnO3 layer thicknesses are prepared by pulsed laser deposition (PLD). The crystal structures (lattice constants) of samples are measured by X-ray diffraction (XRD). The strain of the films is determined according to their crystal structures. The magnetic hysteresis loops (M-H loops) and magnetization versus temperature (M-T) curves of these superlattice films are measured by the physical property measurement system (PPMS). From the M-H loops, the coercive field (H C) of the samples can be measured. From the M-T curves, the Curie temperature (T C) of the samples can be obtained. All samples show a ferromagnetic to paramagnetic transition at TC, and the [La 0. 8 Ca 0. 2 MnO3/La 0. 5 Ca 0. 5 MnO3] 2 0 sample with the La 0. 8 Ca 0. 2 MnO3 layer thicknesses of 72 Å has an antiferromagnetic Néel transition at TN. According to the strain state and magnetic phases, the magnetic properties are comprehensively analyzed. It is found that with the increase of ferromagnetic La 0. 8 Ca 0. 2 MnO3 layer thickness, the ferromagnetic phase is increased, and the double exchange effect can also be enhanced, resulting in the increase of TC. When the thickness of La 0. 8 Ca 0. 2 MnO3 reaches 96 Å, the uneven strain distribution in the superlattice can induce the reduction of ferromagnetic phase compared with antiferromagnetic phase (even antiferromagnetic phase starts to appear), and the double exchange effect can be weakened, and finally leading to the decrease of TC. In addition, with increasing the La 0. 8 Ca 0. 2 MnO3 layer thickness, HC gradually decreases. The change of HC is related to strain states and magnetic phase interactions in the samples. The analysis of the strain and magnetism can contribute to the understanding of perovskite manganite superlattice films. [ABSTRACT FROM AUTHOR]

Li 2 TiO 3 (lithium titanate) is a material of interest in the field of fusion reactors due to its potential application as a tritium breeder material. Because of the extreme working conditions and temperature gradients involved, thermal expansion properties are critical to consider when assessing a material for a fusion reactor. The reactor is subjected to severe neutron flux, high temperature and thermal cycling, which can cause significant stress on the material. A low coefficient of thermal expansion (CTE) of Li 2 TiO 3 is important as it mitigates mechanical stress and minimized the risk of structural damage resulting from thermal cycling. Material degradation, cracking, or delamination might result from a mismatch in CTE between different materials in the reactor. Therefore the estimations of material's thermal expansion properties hold significance for the designing and fabrication of structural material. In this study, Li 2 TiO 3 material was compacted into pellets and high-temperature X-ray diffraction (HT-XRD) was employed to obtain X-ray diffraction patterns from room temperature to 1273 K at 100 K intervals. The lattice parameters (a, b, and c) of Li 2 TiO 3 polycrystals were determined and corresponding unit cell volumes were estimated at each temperature. The thermal expansion percentages for the lattice parameters a, b, and c between room temperature and 1273 K were found to be 1.21%, 1.84%, and 1.83% respectively. The calculated coefficient of thermal expansion (CTE) were determined as 12.5 × 10−6 K−1, 19 × 10−6 K−1, and 18.9 × 10−6 K−1for lattice parameters a, b and c respectively. The crystallographic density at room temperature was estimated to be 3.42 g/cm3. The molar volume was calculated to range between 32.12 and 33.72 cm3/mol from room temperature to 1273 K. Additionally, high-temperature dilatometry was employed to measure the thermal expansion of Li 2 TiO 3 , resulting in the estimation of coefficient of thermal expansion. From room temperature to 1290 K, the thermal expansion percentage and mean coefficient of thermal expansion were calculated to be 1.91% and 19.64 × 10−6 1/K, respectively. Furthermore, the temperature dependent mean and instantaneous thermal expansion values were also determined. The differential scanning calorimetry (DSC) method was used to estimate the temperature of the monoclinic to cubic transformation, which was determined to be 1416 K. This paper provides a comprehensive description of the conducted experiments, accompanied by the detailed analysis of the thermal expansion properties derived through the use of High-Temperature X-Ray Diffraction (HT-XRD) and HT-dilatometry (High-Temperature Dilatometry). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The fabrication of a cadmium sulfide (CdS) thin film has been carried out by the chemical bath deposition method under two different conditions, namely, without UV light (nonexposed) and with UV light (exposed). The thin films were found to be uniform, smooth, and homogenous under both growth conditions. Structural and microstructural studies were carried out to understand the mechanism of thin-film growth. Under both conditions, the CdS thin film was found to be face-centered cubic structured. The UV light-exposed CdS thin film acquired acicular or flower-like over structures embedded in the continuous thin film of CdS. The optical band gap increased for the UV light-exposed CdS thin film. In addition, the dark and light currents also increased around 6 times for the UV light-exposed thin film compared to the nonexposed UV light thin films. The highest photosensitivity for the nonexposed and exposed UV light CdS thin film device was ~ 200% and 230%, respectively. A decrease in the photocurrent was detected and probed as a result of traps and the recombination of electrons and holes. Our findings suggest that photoexcitation during chemical reactions could be used as an effective tool to modulate the growth process and, in turn, to tune the optoelectrical properties. [ABSTRACT FROM AUTHOR]

The electrical parameters of silicon samples diffusion doped by europium impurity atoms were studied by Van der Pauw (VDP) method. The experimental results were examined, particularly the surface morphology using an Atomic Force Microscope (AFM). The lattice constant of the materials was calculated with the help of Bragg-Brentano`s law using X-ray diffraction on the XRD pattern of the Si sample. [ABSTRACT FROM AUTHOR]

In this study, the researchers examined the impact of adding different percentages of nickel (0 %, 0.01 %, 0.05 %, 0.1 wt%) to an aluminum-silicon (Al-Si) alloy. Aluminum alloys are widely used in various industries due to their lightweight nature and favorable mechanical properties. The microstructure of the alloy was analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM) tests.The XRD and SEM analyses revealed that the Al-Si alloy consisted of two phases: α-Al and Si. The introduction of nickel resulted in the detection of an intermetallic compound (IMC) known as Al3Ni. This IMC caused changes in the lattice constant and interatomic spacing (dhkl). The observed distortions and densification in the microstructure were identified as indicators of increased hardness and strength in the alloys. The researchers attribute this enhancement in microstructure properties to the elevated temperature, which facilitated greater diffusion of nickel atoms into the aluminum lattice.

Due to the presence of core effects of high‐entropy materials, it is believed that the impact of carbon vacancy in high‐entropy carbides may differ from that of transition metal monocarbides. In this work, nonstoichiometric high‐entropy carbides (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C1−x (HEC1−x) with variable carbon vacancy concentration were fabricated by spark plasma sintering using powder mixtures of high‐entropy carbide and metallic powders. Compared with the corresponding monocarbides, the decline rates of lattice constant and elastic modulus were obviously slower as carbon vacancy concentration increased, indicating a more rigid crystalline lattice in the high‐entropy carbide. The valence electron number for HEC1−x ceramics with the highest hardness is 7.6, which is inconsistent with the theoretically predicted value of 8.4 for the traditional transition metal carbides. When the carbon vacancy concentration in HEC1−x ceramics is above 20%, the promoting effect of carbon vacancy on grain growth will outweigh the inhibiting effect of sluggish diffusion on grain growth, causing grains to grow quickly. [ABSTRACT FROM AUTHOR]

In this work, Ba0.8In0.2Fe12−xNixO19 (x = 0.00–2.00) hexaferrites were prepared by the ceramic route, and the effect of ferromagnetic dopant Ni was retrieved on the structure and magnetic properties. Microstructural properties were explored using XRD and SEM. The range of the grain size was between 500 to 2000 nm. In addition to these, micro strain, dislocation density, and porosity were determined. According to the VSM findings, ferromagnetic nickel doping increased the magnetic saturation up to 58.36 emu/g. The coercivity values were observed within a defined range from 5.129 kOe to 5.512 kOe, showing only a slight change. Moreover, the magnetocrystalline anisotropy constant, anisotropy field, and anisotropy parameter were calculated. The results showed that the magnetocrystalline anisotropy constant and anisotropy field both increased up to 0.06308 emu/g.kOe and 1.722 kOe for an increase in doping concentrations and then dropped for x = 2.0. The magnetic moment per formula unit in terms of Bohr magneton was also computed and has an upper limit of 11.603. These results suggest that the synthesized material is a good contender for magnetic applications. [ABSTRACT FROM AUTHOR]

In density functional theory (DFT)-based computational methods, electronic properties at optimised atomic position and lattice constants are calculated for semiconducting materials belonging to III–V (GaP, AlP, InP, BP) and II–VI (BeX, MgX, CdX: X =O, S, Se, Te) groups. This paper reports the calculation of equilibrium lattice constants and bulk moduli of the materials under study using five different DFT functionals LDA, PBE, WC, PBEsol and SCAN. The results show that LDA underestimates while PBE overestimates the experimental lattice constants for all these semiconducting materials studied with a mean absolute relative error (%) of the order of 1%. Such trends in LDA and PBE results agree with the earlier reported work. The lattice constants calculated using WC, PBEsol and SCAN are in better agreement with the experiment compared to optB88vdW functional reported by others. On an average, WC and PBEsol functional have been found to be better in estimating the lattice constants and bulk modulus of II–VI binary compounds. We also present the band-gap calculations of the materials under study using different exchange-correlation functionals. The modified Becke–Johnson approximation suggested by Tran and Blaha is found to provide a better agreement with the experimentally reported results than the standard DFT method. [ABSTRACT FROM AUTHOR]

This paper attempts to find the possibility of describing the supplementary parameters of the macroscopic crack strength field based on the variation at the microscopic level. The analysis focuses on the development of cracks in the vicinity of the crack tip of a central crack panel made from iron material with a cubic crystal structure under tensile loading. We use the combination of finite element and molecular dynamics simulation methods. Molecular dynamics simulation analysis shows that the motion velocity of molecules near the crack tip region is less than the Rayleigh wave velocity, VR, which is about 0:22 VR. The average velocity is smaller in other directions that are not parallel to the crack. The velocity of the molecular near the crack tip indicates the ductile phenomenon of the crack tip region because it comes from the potential energy, which means that on the crack extension line, the kinetic energy of the molecular motion is greater than that in the other directions but is close to that in the 45° direction. It shows that the crack expansion direction is still mainly along the crack extension line under the load. [ABSTRACT FROM AUTHOR]

In this work, the physical features of growing epitaxial layers of new solid solutions of (GaAs) 1 − y − z (Ge 2 ) y (ZnSe) z from the liquid phase of the tin solution-melt on GaAs (100) substrates were investigated. The conditions required for the formation of the solid solution of molecular substitution were revealed. A possible configuration of the crystal structure of the solid solution (GaAs) 1 − y − z (Ge 2 ) y (ZnSe) z is presented. In the spectral photosensitivity of the n -GaAs– p -(GaAs) 1 − y − z (Ge 2 ) y (ZnSe) z structures, peaks with maxima at photon energies of 1.37 eV and 2.62 eV were found. The band diagram of the solid solution (GaAs) 1 − y − z (Ge 2 ) y (ZnSe) z was presented. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiaotong University (Science) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Perovskite materials have a variety of crystal structures, and the properties of crystalline materials are greatly influenced by geometric information such as the space group, crystal system, and lattice constant. It used to be mostly obtained using calculations based on density functional theory (DFT) and experimental data from X-ray diffraction (XRD) curve fitting. These two techniques cannot be utilized to identify materials on a wide scale in businesses since they require expensive equipment and take a lot of time. Machine learning (ML), which is based on big data statistics and nonlinear modeling, has advanced significantly in recent years and is now capable of swiftly and reliably predicting the structures of materials with known chemical ratios based on a few key material-specific factors. A dataset encompassing 1647 perovskite compounds in seven crystal systems was obtained from the Materials Project database for this study, which used the ABX3 perovskite system as its research object. A descriptor called the bond-valence vector sum (BVVS) is presented to describe the intricate geometry of perovskites in addition to information on the usual chemical composition of the elements. Additionally, a model for the automatic identification of perovskite structures was built through a comparison of various ML techniques. It is possible to identify the space group and crystal system using just a small dataset of 10 feature descriptors. The highest accuracy is 0.955 and 0.974, and the highest correlation coefficient (R2) value of the lattice constant can reach 0.887, making this a quick and efficient method for determining the crystal structure. [ABSTRACT FROM AUTHOR]

Porous hydroxyapatite (HAp) ceramics with macropores of more than 200 μm were fabricated via our new method comprising chemical synthesis and heat treatment. In this study, four types of porous Zn-doped HAp ceramics were produced by adding 0.1, 0.5, 1.0 and 5.0 g of zinc acetate dehydrate to 50 g of a HAp nanoparticle slurry during chemical synthesis and then calcining the mixtures at 1200 °C. Three samples fabricated by adding 0.5, 1.0 and 5.0 g of zinc acetate dehydrate showed a ZnO phase as a byproduct. In contrast, the sample fabricated by adding 0.1 g of zinc acetate dehydrate did not show it. As the additive amounts of Zn ions increased, lattice parameters a and c of the HAp phase increased. By inserting Zn ions into OH channels within HAp lattices, the hydroxyl groups within them decreased, and consequently, the lattice parameter c increased by forming linear O—Zn—O units within them. On the other hand, the lattice parameter a increased because the HAp lattices were disordered owing to the insertion of Zn ions. Moreover, upon examining the cell behavior of our samples, the cells adhered well to and spread widely on the sample without the ZnO phase, similar to porous undoped HAp ceramics 48 h after cell culture. Namely, Zn ions that were themselves inserted into the HAp lattice did not significantly influence cell adhesion. In contrast, the number of adhering cells on the samples with the ZnO phase decreased compared to that without it. [ABSTRACT FROM AUTHOR]

ZnOxS1−x has attracted enormous interest because of its potential application in optoelectronic devices. So far, investigations on zinc blende (ZB) ZnOxS1−x alloys in the S-rich range are relatively few. In order to better understand it, first-principles calculations are employed to calculate its lattice constant and bandgap energy. It is found that the lattice constant in the S-rich range has a small negative bowing coefficient. It is also found that the downward shift of the conduction band minimum (CBM) is attributable to the coupling interaction between the O-2s and Zn-4s states, narrowing the bandgap. The valence band maximum determined by the coupling interaction between the S-3p and Zn-3d states also exhibits a downward trend. However, its downward movement makes no contribution to the bandgap reduction. Additionally, the initial O impurity level lying above the CBM of the ZB-ZnS does not exhibit an obvious localized character, so it is unable to be lined up with the initial O level in ZnSe or ZnTe. In order to describe the bandgap energy of the S-rich ZnOxS1−x, a model is applied. It is observed that the model can provide a good description. [ABSTRACT FROM AUTHOR]

The transfer energy of oxygen vacancy of La and Y co-doped CeO2 is investigated in which the total amount of La and Y is fixed at 20 at%. Although both the La3+ (1.16 Å) and Y3+ (1.032 Å) ions are larger than the Ce4+ ions (0.97 Å), individual single doping of La and Y results in an increase and a decrease in the CeO2 lattice constant, respectively, due to the effect of the critical ionic radius (rc). As the La/Y ratio varies, the lattice constant increases as the La content increases, which leads to a decrease in the migration energy of the oxygen vacancy in the grain interior. When La and Y are co-doped at a ratio of 2:18, its lattice constant is almost the same as that of pure CeO2 in which the dissociation energy of the oxygen vacancy achieves the lowest value due to the minimum lattice-strain energy. The migration energy at the grain boundary also decreases with increasing La content. This result is explained by the degree of grain boundary segregation of the dopant.

Molecular dynamic (MD) simulations of hydrates of methane (CH4) and carbon dioxide (CO2) were carried out. The force fields TIP4P/2005, OPLS-UA, and TraPPE, were used. The lattice constant and thermal expansion coefficient were obtained as a function of temperature. Considering the results of the current simulations and experimental literature data, a simple, meaningful polynomial (a function of temperature) was used to fit the obtained lattice constants from 0 to 283.15 K. The derivative structural property of the isobaric thermal expansion coefficient was calculated from fluctuation through MD simulations. While failing to capture the true behavior at low temperatures (i.e., less than 100 K), the MD simulation results of lattice constants and isobaric thermal expansion coefficients are consistent at higher temperatures, which is the most important situation for practical applications of hydrates as energy source or gas storage medium. [ABSTRACT FROM AUTHOR]

Long-term thermal cycling causes irreversible dimensional changes of the material, which in turn affects the reliability of precision instruments. In this paper, dimensional stability mechanisms of SiC/Al composites during thermal cycling were revealed using high-precision thermal dilatometer, XRD and spherical aberration correction transmission electron microscope (Cs-TEM). First, how the factors including dislocations, internal stress and precipitates affect the dimensional change of SiC/Al composites were separately introduced. Then, the integrated effect of these factors affecting the dimensional stability of SiC/Al composites was further discussed. Among them, the integrated effect of dislocation-internal stress in SiC/pure Al composites leads to an increase in dislocation density and average lattice constant, which leads to an increase in dimensional change. The integrated effect of dislocation-internal stress-precipitates in SiC/2024Al composites leads to a decrease in the average lattice constant and some changes in the precipitation behavior (including the type, density and lattice constant of the precipitates), which ultimately leads to a decrease in dimensional change. The dimensional change of the two types of composites was semi-quantitatively estimated. Finally, the reasons for the significantly higher dimensional stability of the SiC/2024Al composites were given. [ABSTRACT FROM AUTHOR]

Photonic crystals (PhC) can be elaborately tailored to enhance the electromagnetic properties of materials and are drawing increasing attention in recent years. However, there is no sufficient theoretical framework to optimize photonic crystal designs for electric enhancement. A comprehensive theoretical model is presented to illustrate Au/Ag photonic crystal enhancement on electric fields and obtain a group of optimal photonic crystal parameters after large number of statistics and parameter scans. The second and deeper layers of PhC only contribute to both 5% extinction and absorption in the far‐field, and there is almost no difference in |E|max among different layers with the coefficient variation at ≈1%. Furthermore, increment of both lattice constants and NP diameters can trigger dramatic changes in |E|max, and the maximal |E|max derived from 190 nm AuNP (nanoparticle)‐Au PhC with the lattice constant of 560 nm. This structure is 47.7, 7.39, 4.63, and 2.69 times that of AuNP incorporated silica wafer, silicon wafer, Ag wafer, and Au wafer, respectively. The strong electric field enhancement attributes to not only the plasmonic effect but also the photonic crystal enhancement effect. The simulation procedures open the possibility of precise photonic crystal structure design and pave the way for various electric field enhancement applications. [ABSTRACT FROM AUTHOR]

Sol-gel procedure was taken into consideration to produce ferrite series with chemical formula MnYbyFe2-yO4 with y = 0.00 to 0.10 (step = 0.025). Structural, electrical and magnetic aspects of ytterbium (Yb) switched Mn-ferrites were the main focus. Every sample exhibited cubic phase spinel assembly. Exchange of ytterbium with iron in the system produced enlargement in coercivity while abridgment in remanence and saturation magnetization. Involvement of Yb ion in the ferrite assembly led to reduction of both real and imaginary constituents of permittivity. The ytterbium introduction in the lattice enhanced the value of impedance. The examination of hysteresis loop was done under the range of -2K to +2KOe. Temperature dependent resistivity, activation energy and drift mobility were carried out by two probe method. The characterization outcomes recommended that the compounds are appropriate for microwave absorption usages.

This study aims to evaluate the effects of multiple defect species produced by water and oxygen incorporation on the lattice parameters of BaZr 0.8 Yb 0.2 O 3-δ (BZYb20) and model its chemical expansion considering these effects. In this study, the lattice constant of BZYb20 was investigated under oxygen partial pressure (p O 2 = 1–10−3 bar), water vapor partial pressure (p H 2 O = 0.0023 bar and dry) and over a wide range of temperatures (473–1173 K) using two approaches: model calculations and high-temperature X-ray diffraction (HT-XRD). HT-XRD measurements revealed that the lattice expansion of BZYb20 changed within 700–900 K in a humidified atmosphere. In a nonhumidified atmosphere, this temperature range shifts lower. High-temperature gravimetric measurements of oxygen incorporation showed that the change in oxygen vacancy concentration was sufficiently small, and the effect of oxygen incorporation on the lattice constant was negligible. High-temperature gravimetric measurements of water incorporation yielded thermodynamic parameters for the hydration reaction. Based on these results, the HT-XRD results were reproduced by fitting a lattice constant model that neglects the effects of oxygen. Therefore, the effect of oxygen incorporation on chemical expansion can be ignored, and the chemical expansion can be estimated using the model developed in this study. [Display omitted] [ABSTRACT FROM AUTHOR]

The present work illustrates the deformation behaviour of tungsten heavy alloys (WHAs) using first-principles calculation under tensile stress of three virtual alloy systems comprising the matrix phase and a W-grain along with two fcc–bcc interfaces. The energy values of the alloy systems decrease with the additions of Co and Co + Mo in the ternary alloy (W–Ni–Fe). The experimental lattice parameters of the matrix phase of alloys are in good agreement with those of the alloy systems calculated using the first-principles calculation. The lattice constants, yield strength and strength at 20% strain increase with the additions of Co and Co + Mo. The nature of theoretical stress–strain curves of systems is similar to those of the experimental stress–strain curves of typical alloys. The nitty-gritty of virtual alloy systems and the interrelated consequences resulting in closer to real alloys in terms of tensile flow curves have been discussed. [ABSTRACT FROM AUTHOR]

In this paper, we have developed models based on Deep-Learning Neural Network (DNN) for accurately predicting lattice constants of half-Heusler alloys. A commercial software WIEN2k employing the Density Functional Theory (DFT) is first used to generate data of the lattice constants of 377 half-Heusler alloys for the training, testing and validation of the models. These models use elemental symbols or/and ionic radii as input parameters. The model that uses only symbols of the constituent element and the model that uses symbols in combination with the radii of the ions predict lattice constants of half-Heusler alloys with an average error of less than 1% to the data obtained from the WIEN2k calculations. The average error stays below 2% in the prediction by the model that uses radii of the ions alone. These results show a great promise for these models to be extended for the prediction of structural and elastic properties of not only new half-Heusler alloys but also other new materials such as full-Heusler, spinels, perovskites, etc. with greater convenience, saving hours of computation time. [ABSTRACT FROM AUTHOR]

Structural features such as the shape, the lattice constant, the bond length, the total energy per cell, and the energy bandgap (Eg) of C13H8OS-X are studied by the calculating Partial Density Of States (PDOS), and DOS package of the Material Studio (MS) software. Calculations show that the bond length and the bond angle between atoms insignificant change as 1.316 Å to 1.514 Å for C-C, 1.211 Å for C-O, 1.077 Å to 1.105 Å for C-H; bond angle of round one changes from 118.883° to 121.107° for C-C-C, from 117.199° to 122.635° for H-C-C, from 119.554° to 123.147° for C-C-O and from 109.956° to 117.537° for C-C-H. When C13H8OS-X doped in the order of -Br, -Cu, -Kr, -Ge, -As, and -Fe then bond lengths, bond angles between atoms have a nearly constant value. Particularly for links C-X, there is a huge change in value, respectively 1.876, 1.909, 10.675, 2.025, 2.016, 2.014 Å; the total energy change from Etot = −121,794 eV to Etot = −202,859 eV, and the energy band gap decreases from Eg = 2.001 eV to Eg = 0.915 eV. The obtained results are useful and serve as a basis for future experimental research.

Heterostructures with lattice mismatched and compositionally different layers are widely used in modern electronic and optoelectronic device engineering. Generally such structures are manufactured by the methods of metal-organic vapor phase epitaxy, metal-organic chemical vapor deposition and molecular-beam epitaxy. However, the methods of deposition from a liquid phase are the most inexpensive and simple yet. Thus obtaining the above mentioned heterostructures from a liquid phase is still promising. In this work we demonstrated the possibility of using the method of scanning liquid phase epitaxy to grow continuous heteroepitaxial layers over the substrate surface highly mismatched by lattice constant and having different crystal-chemical properties. By controlling basic parameters of the method we created the conditions close to the solution-melt saturation limit. In other words, we created the conditions of ultra-fast solution-melt cooling and, respectively, high growth rate. We obtained the heterostructures of Ge layers grown on GaP substrates where the lattice mismatch made 3.7%. Gallium was used as the solvent for Germanium. The heterostructure was grown by the method of scanning liquid phase epitaxy in the conditions of ultra-fast initial cooling of the solution-melt. Overcooling at the crystallization front was controlled by an extra heater of the substrate back side. The growing time was 1 and 20 seconds for the two test samples. The layers thickness was determined by the spherical slice technique to be 1.2 and 1.5 μm for these two growing time values, accordingly. We showed that it was possible to obtain more perfect Ge layers on GaP substrate by lowering the growth rate in the final growth stage. This method can be used to grow heterostructures used in creating such modern electronic and optoelectronic devices as structures based on A3B5 compounds and their solid solutions, which cannot be obtained by other classical methods of liquid phase epitaxy due to significant differences in lattice constants and / or crystal-chemical properties.

Main applications of isotopic Silicon in new areas were briefly introduced. The work done by the author’s institute on Silicon isotope separation and measurement of 28Si epitaxial wafer and diodes in early year was presented. For precisely measurement of Avogadro constant as basic metrology unit of kilogram using 28Si, relation of isotope abundance and lattice constant deviation was reduced. Examples were calculated using the relation, thus the requirement of Silicon abundance was estimated.

xCo–5%Ni (where x = 0, 1, 3, and 5%) coatings on bentonite were synthesized by insipient wet impregnation method. The phase structures of the coatings, surface analysis, dielectric property of the samples as a function of frequency (at room temperature), were characterized using X-ray diffractometer, energy-dispersive X-ray spectroscopy (EDX) and analytical response analyzer, respectively. The EDX confirmed the presence of Ni and Co in proportions qualitatively consistent with the concentrations of the synthesized composites. X-ray diffraction measurement confirmed the presence of montmorillonite and quartz as the main components in bentonite. Peaks shift has been noticed toward lower diffraction angle in bentonite X-ray diffractogram after insertion of metal ions (Ni and Co ions) which might be due to lattice expansion. The lattice constant was found to be 4.35, 4.42, and 4.41 Å for 1%Co–5%Ni/bentonite, 3%Co–5%Ni/bentonite and 5%Co–5%Ni/bentonite, respectively. The diffraction peak at 37.2°, observed for all composites, was ascribed to (111) plane of the NiO cubic phase. The crystallite size has been calculated by Scherer formula and was found to increase from 3.19 to 8.43 nm with increasing the wt% of Co. The dielectric permittivity has decreased with increasing frequency and further decreased by doping. The value of AC conductivity has increased with an increase in frequency. The conduction mechanism for doped samples was hopping, while that for bentonite was due to the localized/reorientation processes. [ABSTRACT FROM AUTHOR]