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Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Using first-principles calculations based on density-functional theory, this paper investigates the electronic structure and magnetic properties of the Heusler alloy Mn2LiGe bulk and its (001) surfaces. The Mn2LiGe bulk is demonstrated to be inverse Heusler alloy with space group of F43m and lattice constant of 5. 87 Å. A direct band gap with a width of 1. 1 eV near the Fermi surface of the spin-down channel is detected. The Mn2LiGe bulk possesses stable half-metallic and magnetism in the lattice constant range of 5. 55 - 6. 33 Å. In addition, six different surface structures of Mn2LiGe are constructed in this paper. The first layer atoms on the surface undergo different displacements, increasing the surface roughness. Due to surface effects, the magnetic properties of atoms on the surface are different compared to those in the bulk. Both the MnA MnA and MnB MnB surface structures have the highest magnetic moments, while the LiLi and the GeGe surface structures have the lowest magnetic moments. Electronic structure calculations show that the half-metallic band gap present in the bulk is destroyed in all six surface structures and the spin polarization is weakened in varying degrees. Only the LiLi surface structure maintains up to 99. 9% of the surface spin polarization, making the surface an excellent prospect for applications in spintronic devices. [ABSTRACT FROM AUTHOR]

The influence of frequency characteristics of devices is complex. The effects of AlN barrier thickness, gate length, gate-drain spacing and work function on the frequency characteristics of AlN/ β-Ga2O3 high electron mobility transistor (HEMT) were studied by Sentaurus TCAD in this paper. The following conclusions are obtained: as the thickness of the AlN barrier layer increases from 10 nm to 25 nm, the cutoff frequency (fT) and maximum oscillation frequency (fmax ) rise by 18 and 17 GHz respectively. The decrease of gate capacitance is the main reason for the increase of fT . Furthermore, it was found that the thinner barrier layer enhanced the gate's ability to control the channel electrons. When the gate length is scaled down from 0. 9 μm to 0. 1 μm, fT and fmax increase by 84 and 98 GHz, respectively, representing a far more profound influence on frequency characteristics than the barrier layer thickness. However, when the gate length fell below 0. 1 μm, short-channel effects emerged. As the gate-drain spacing increase, fT exhibits a slight decrease. Coupled with the concurrent reduction in source resistance, this led to a synchronized trend in fmax and fT only when the gate-source voltage (VGS ) exceeds - 1. 2 V. The work function, on the other hand, has minimal impacts on fT and fmax, but an increase in the work function positively influenced the device' s pinch-off characteristics. In summary, this paper indicates that by shortening the gate length while concurrently augmenting the thickness of the AlN barrier layer, gate-drain spacing, and work function, one can enhance the frequency characteristics while also improving the pinch-off characteristics of the device, which has certain guiding significance for the design of HEMT devices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

This paper delves into the synthesis strategies of molybdenum disulfide (MoS2) nanomaterials and their prospective applications in the fields of energy conversion and storage. Through a comprehensive analysis of various synthesis methods, including solvothermal and sol-gel processes, the specific impacts of these methods on the morphology and properties of MoS2 nanostructures are revealed. The study indicates that MoS2 nanomaterials with optimized electronic properties and surface activity can be fabricated by precisely controlling the synthesis conditions. These materials demonstrate exceptional performance in applications such as lithium-ion batteries and photodetectors, especially in enhancing battery charge-discharge cycle stability and improving photoelectric conversion efficiency. The paper further discusses the challenges faced in the development of MoS2 applications, particularly in terms of the scalability of material synthesis and consistency of performance. Lastly, the article presents a vision for future research directions, emphasizing the potential to broaden the application of MoS2 in high-performance energy devices through innovative synthesis strategies and material structure optimization. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Diamond possesses an ultra-high thermal conductivity and a wide band-gap. Its electrical resistance could be adjusted for the semiconductor application by increasing the electron and vacancy content introduced by doping different elements. Therefore, diamond is thought to be the final wide band-gap semiconductor materials. This paper firstly introduces the synthesis of diamond by high-pressure and high-temperature (HPHT) method, and then systematically reviews the current status and developments of diamond doping by HPHT. The effects of single-element doping, such as N, B, P, and S, as well as multi-elements co-doping in the diamond crystal growth and its electrical properties are analyzed. In additional, this paper summaries the study diamond doping using first-principle calculation. HPHT annealing could effectively change the combinations of doped elements and the associated vacancies and their distribution. This paper reviews the adjustment of nitrogen-related color centers in diamond by HPHT annealing, elucidating the formation mechanisms of various nitrogen-related color centers. Finally, This paper prospects the potential optical and electrical properties of doped diamonds, highlighting the importance of theoretical calculations and experimental methods for multi-element co-doping investigation to enhance the performance of doped diamonds. [ABSTRACT FROM AUTHOR]

The up-conversion (UC) luminescent properties of rare earth broaden the development of photocatalsyts. Rare earth elements and up-conversion agents all could promote the photocatalytic activity and research value by broadening the light response from infrared to violet irradiation in the field of photocatalytic technology. This paper reviewed the research progress of the rare earth up-conversion luminescent photocatalysts. Er, Yb, Tm, Ho and Tb are the main elements which have properties of up-conversion luminescence, of which Yb is usually taken as the sensitizing agent while Er is the most widely studied because of its efficient and green luminescent properties. According to their different structures, rare earth up-conversion agents are classified into three categories: rare earth fluoride, rare earth oxyhalide, and rare earth oxides or composite oxides. NaYF4 was studied widely because of its outstanding properties. Although the excellent properties of rare earth UC materials, there still exists some drawbacks, especially the low quantum efficiency of UC materials, which greatly limits the photocatalytic activities. Therefore, the rare earth UC photocatalysts need further construction and research. This paper intends to provide some inspiration and help for the researches in the area of full spectrum photocatlaysts. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Biomass-derived carbon materials represents promising electrode materials for supercapacitors owing to wide range of precursor sources, large specific surface area, intrinsic heteroatom doping, and controllable pore structure. Additionally, increasing attention has been garnered for significant role in alleviating environmental problems, enhancing waste utilization, and promoting sustainable energy storage applications. This paper summarizes recent advances of biomass-derived carbon materials for supercapacitors with focus on main sources of biomass precursors, preparation strategies and nanostructure for biomass-derived carbon. Then, the pore structure, specific surface area and electrochemical performance of biomass carbon constructed by different strategies (carbonization method, activation method and heteroatom doping) are elaborated. The effect of nanoscale pore structure on their performance is emphasized. Finally, the development prospects and main challenges of biochar in supercapacitors are proposed. This review would provide valuable insights for future development and efficient utilization of biomass carbon. [ABSTRACT FROM AUTHOR]

As a new type of semiconductor material, halide perovskite materials has the advantages of low cost and excellent photoelectric conversion performance. Various photoelectric devices based on the halide perovskite materials have begun to be gradually applied. Polycrystalline thin films are still the main research direction, however, they have the disadvantages of disordered morphology and many impurities. In contrast, single crystals have the characteristics of no grain boundaries and low defects. Therefore, the research based on large-size single crystals gained widely concerned. In this paper, a set of internal and external reverse temperature control cycle filtration growth devices was designed. The CH3NH3PbBr3 single crystal with a diameter of more than 60 mm was prepared by the combination of inverse temperature crystallization and seed crystal. The phase, microstructure, and optical and electrical properties of the crystal samples were studied. The crystal belongs to the cubic system with space group of Pm3m. The ultraviolet-visible absorption spectrum shows that the absorption cut-off edge is about 576 nm and the fluorescence emission spectrum peak is 552 nm. The rocking curve shows that the half width at maximum of the crystal (100) plane is 91. 42". The wafer after cutting and polishing is sensitive to photo response, and the on-off ratio is 2. 4 x 104. [ABSTRACT FROM AUTHOR]

Abstract:In this paper, porous n-GaN thin films with a pore density of 1. 51 x 1010 Cm-2 and an average pore size of 38 nm were initially prepared by UV-assisted electrochemical etching (UV-EC). Subsequently, a series of ZnxCu1- xS composite films, with x values of 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, were deposited on the porous n-GaN films by water bath method. The bandgaps of the porous n-GaN/ZnxCu1-xS heterojunctions varied in the range from 2. 34 eV to 3. 51 eV. Hall test results demonstrate that when x values is less than 1, the ZnxCu1-xS composite films exhibit p-type semiconductor properties. Furthermore, increasing the proportion of CuS leads to an improvement in the conductivity of the composite films. Additionally, XPS results confirm that both Cu and Zn possess a + 2 valence within the composite films. When ZnxCu1-xS forms a heterojunction with porous n-GaN, the energy band structures of both materials interact to create a built-in electric field. This field facilitates the efficient separation of photogenerated electron-hole pairs. Finally, p-n heterojunctions UV detectors were constructed based on these heterostructures. The I-V curve results indicate that these detectors exhibit good rectification characteristics. Notably, the n-GaN/p-Zn0.4Cu0.6 S detector demonstrates optimal performance. In the dark state, I+3V/I-3V is approximately 1. 78 x 105. Under a bias voltage of - 3 V and an optical power density of 432 μW/cm² (ultraviolet light at 365 nm), this detector's photo-to-dark current ratio exceeds 103, the rise/fall time is 0.09/39.8 ms, responsivity(R) reaches 0. 352 A/W, the external quantum efficiency (EQE) stands at 119.6%, and detectivity(D*) is 3. 21 x 1012 Jones. The I-t curve results indicate that the porous n-GaN/p-ZnxCu1-xS heterojunctions UV detector possesses reproducible performance during the consecutive on-off optical cycling process with reproducible photocurrent response. This study offers valuable theoretical insights and a comprehensive understanding of the physical properties and performance characteristics of these novel heterostructures UV detectors. [ABSTRACT FROM AUTHOR]

Due to their unique physical and chemical properties, wide bandgap semiconductor materials have shown great potential in the field of optoelectronic devices, and have received more and more research and attention. Zinc gallate (ZnGa2O4) is a wide bandgap semiconductor material, showing broad application prospects in the fields of solar-blind ultraviolet photoelectric detection and X-ray detection for its wide bandgap, unique structure and good thermal stability. In this paper, based on the basic structural characteristics of ZnGa2O4, the bandgap, photoelectric properties of ZnGa2 O4, the preparation methods of ZnGa2O4 bulk single crystal and thin film are introduced in detail. Combined with the recent research results of domestic and foreign scholars, the application prospects of ZnGa2 O4 in many fields are summarized, especially the research progress of solar-blind ultraviolet photoelectric detection, memristor, X-ray detection and power devices. Finally, the future development direction of ZnGa2O4 is prospected, and it is pointed out that the quality and performance of ZnGa2O4materials can be further improved to improve device performance and meet higher level application requirements. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

This paper systematically reviews the research advancements in indium oxide (In2 O3)-based gas-sensitive materials and focuses on their potential applications in environmental monitoring and safety. It provides an in-depth analysis of the structure, properties and gas sensing mechanisms of indium oxide, detailing the impact of various synthesis methods (such as hydrothermal and chemical vapor deposition) on the microstructure and performance of the materials. Additionally, this paper discusses the applications of modification techniques, including element doping, material loading and semiconductor compositing in enhancing gas sensitivity. It also analyzes current research challenges and future directions, offering significant perspectives and directions for further research and application of indium oxide-based gas-sensitive materials. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

In this paper, aurichalcite was synthesized by ammonia distillation method, using basic copper carbonate, basic zinc carbonate and concentrated ammonia as raw materials. The effects of process conditions on the crystal structure of aurichalcite were studied by XRD, TGA, SEM-Mapping and FT-IR. It is demonstrated that when the copper concentration is fixed at 120 g/L, and the molar ratios of copper to zinc are set at 3:2, 1:1 and 2:3, respectively, the crystals in the precipitation product consist of aurichalcite and malachite. As the molar ratio of copper to zinc decrease, the number of malachite crystals decrease. When the molar ratio of copper to zinc is 2:3, a further reduction in the number of malachite crystals is observed when the copper concentration reduce from 120 g/L to 80 g/L. Finally, under the condition that the molar ratio of copper to zinc is 2:3 and the copper concentration is 80 g/L, single-phase aurichalcite crystals are precipitated. This provides basic data for controlling the synthesis of aurichalcite by ammonia distillation method. [ABSTRACT FROM AUTHOR]

In this paper, a new GaSe/ZnS van der Waals heterostructure (vdWH) is devised and subjected to systematic analysis through first principles calculations in terms of its geometric, electronic and transport properties. The stability of GaSe/ZnS vdWH is verified through binding energy, phonon spectrum, and ab initio molecular dynamics (AIMD) simulation. Additionally, detailed calculations of plane average electron density difference and average electrostatic potential in the features of GaSe/ZnS vdWH interface are provided. The results show that GaSe/ ZnS vdWH comprises a heterostructure with a direct band gap of 2.19 eV and high carrier mobility. Among them, the electron mobility along the x direction reaches 1 394.63 cm²V-1⋅s-1, while the electron mobility along the y direction reaches 1 913.18 cm² ⋅V-1 ⋅s-1, demonstrating excellent performance and potential applications in electronic nano devices. [ABSTRACT FROM AUTHOR]

With the rapid development of silicon-based light detectors with high detection efficiency and long-wavelength sensitivity, the development of near-infrared scintillation crystals has become a hotspot. Especially, the Sm2+ doped europium-based halide crystals exhibit excellent near-infrared luminescence properties. In this paper, Cs4 EuI6: Sm near-infrared scintillation crystals with a size of cm-level were successfully prepared by Bridgman method. The composition and structure were discussed by XRD, XPS and ICP-OES methods, indicating that the Sm2+ was introduced and has no obvious effect on the crystal structure of the matrix. Under ultraviolet and X-ray excitation, the crystal has two luminescence centers (Eu2+ and Sm2+), and the emission peaks are located at 450 and 840 nm, respectively, corresponding to the 5d→4f luminescence of Eu2+ and Sm2+. The decay time of Eu2+ and Sm2+ is at the level of microsecond under ultraviolet excitation. The results show that the emission wavelength gradually varies from blue to near infrared as Sm2+ doping concentration increased. The effects of Sm2+ concentration on the luminescence properties, Eu2+ -Sm2+ energy transfer and decay time of the crystals were also studied, which means that the luminescence properties can be tuned by adjusting the Sm2+ doping concentration. [ABSTRACT FROM AUTHOR]

X-ray and γ-ray detection have been extensively studied and applied in medical imaging, security inspection, homeland security, non-destructive testing and other various fields. Perovskite materials have become excellent candidates for radiation detector devices due to their high radiation absorption coefficient, high carrier mobility-lifetime product and defect tolerance. The solution method offers significant advantages in the preparation of perovskite materials. It is a cost-effective approach that can be carried out at low temperatures or under ambient conditions. Additionally, it is also easier to implement for industrial production. This method plays a crucial role in optimizing the material system and achieving the preparation of high quality and large area crystal materials in the future. This paper analyzes the effects of crystal growth and material composition on radiation detection performance, focusing on the solution preparation of perovskite materials. The study aims to improve radiation detection performance by optimizing crystal growth quality and device structure design. Additionally, it also summarises the challenges faced by perovskite materials in the field of radiation detection and suggests future research directions. The results of this study are expected to serve as a reference for the industrialization of perovskite materials in the field of radiation detection. [ABSTRACT FROM AUTHOR]

In order to solve the problem of thermal conductivity test of large-size diamond, the ϕ100 mm sample holder of vertical mode and In-Plane mode was designed for the NETZSCH LFA467 HyperFlash instrument. The test results of the ϕ100 mm sample holder are proved to be credible from both principle and test results. From the theoretical analysis, it is concluded that the change of sample boundary conditions brought by the new sample holder has little effect on the test results. The thermal conductivity test results of the ϕ100 mm sample holder in the In-Plane mode are 6. 5% higher than that of the standard sample holder, and the thermal conductivity test results of the ϕ100 mm sample holder in the vertical mode are 3. 6% higher than that of the standard sample holder. The test results are still within the acceptable range. The ϕ100 mm sample holder designed in this paper can test ϕ100 mm samples at most, which helps to protect the integrity of samples. In this paper, the non-destructive testing of thermal conductivity of large-size diamond by laser flash method is realized. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals 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.)

Acoustic hyperbolic metamaterials are artificial materials with hyperbolic dispersion characteristics and strong anisotropy. Their negative refractive properties are the theoretical basis for studying the implementation of high-resolution focused superlenses. In response to the problem that the recognition of far-field noise sources is limited by the resolution of 0. 5 times wavelength acoustic Rayleigh diffraction recognition, combined with the excellent control effect of acoustic metamaterials on sound waves, a hyperbolic metamaterial that can achieve sub wavelength super-resolution imaging is introduced, and its negative refractive characteristics are used to design an acoustic hyperbolic structure for working at a frequency of 2 271. 5 Hz. The dispersion and negative refraction characteristics of the hyperbolic structure of this configuration were analyzed, and the results show that, the group velocity direction of sound waves propagating in this hyperbolic metamaterial is perpendicular to the wave vector and follows the normal direction of the dispersion curve. The research in this paper provides some design references for realizing arbitrary regulation of sound wave and elastic wave, as well as focusing, locating, identifying and amplifying noise sources. [ABSTRACT FROM AUTHOR]

Proton exchange membranes (PEMs) have key functions in fuel cells. They separate the cathode and anode, provide channel for proton transport, and block the fuel permeation in the battery. Perfluorosulfonic acid membrane like Nafion has excellent chemical stability, thermal stability, and high proton conductivity. However, it also has problems such as high cost, poor mechanical performance and low proton conductivity at high temperatures, and easy degradation. Metal organic frameworks (MOFs) are attractive candidates for PEMs due to their high porosity, large specific surface area and controllable internal channels. MOFs have been used as proton conductors directly, or to modify and improve the existing ionic polymer PEMs, and a series of important progresses have been achieved. In this paper, four common proton conduction modes of MOFs structure proton conductors are reviewed, and the related studies of MOFs in different types of ionic polymer composite PEMs are summarized. Moreover, current issues on MOFs proton conductors and their PEMs are pointed out, which provides references and ideas for the development and application of MOFs as PEMs. [ABSTRACT FROM AUTHOR]

In this paper, mullite porous ceramics were prepared by dry compression molding method using construction waste as main raw material, alumina as aluminum source, aluminum fluoride as whisker catalyst, boron oxide, cerium oxide and molybdenum trioxide as sintering aids, and corn starch as pore forming additive. The effects of cerium oxide and molybdenum trioxide contents on the structure and physicochemical properties of the mullite porous ceramics were investigated, and the ceramics with the best performance were loaded with TiO2 / Ce-TiO2 for photocatalytic degradation of simulated printing and dyeing wastewater. The results show that, in terms of mass fraction, when the content of cerium oxide is 4% and the content of molybdenum trioxide is 1%, the flexural strength of porous ceramics is 8. 69 MPa, and the open porosity is 64. 25%. Loading with 0. 05 g Ce-TiO2 and mixing with 1. 2 mmol / L PMS, the degradation rate of the methylene blue solution reaches 96. 62% after 120 min of irradiation with LED visible light at power of 18 W and wavelength of 420 - 430 nm. [ABSTRACT FROM AUTHOR]

In this paper, a series of novel Sr3-xGa2Ge4O14:xDy3+ (x = 0 - 0. 40) (mole fraction) and Sr2.68Ga2Ge4O14 :0. 16Dy3+, 0. 16M+ (M = Li, Na, K) phosphors were prepared by high-temperature solid-phase method. EDS analysis confirms the presence of Sr, Ga, Ge, O and Dy elements in the phosphors. The series Sr3-xGa2Ge4O14 :xDy3+ produce strong yellow light emission with 568 nm as the dominant wavelength under 350 nm optical excitation, corresponding to the 4F9/2→6H13/2 transition. The emission spectra of the phosphor show that the emission intensity varies with the increase of Dy3+ concentration and reaches its maximum at x = 0. 16. The co-doping of alkali metal M(M = Li, Na, K) as a charge compensation ion, among which Li+ has the most obvious effect on increasing the emission intensity of Dy3+, led to the increase of the emission intensity of the phosphor to twice that of the phosphor in the absence of the charge compensation ion. In addition, the fluorescence lifetime of the phosphor decrease continuously with the increase of Dy3+ doping concentration. Finally, the CIE chromaticity coordinates and thermal stability of the phosphor Sr2.68Ga2Ge4O14 :0.16Dy3+, 0.16Li+ are explored, and its CIE chromaticity coordinates are (0. 371 9, 0.404 6), which are located in the yellow region, and its luminescence intensity at 453 K is about 95. 5% of its room temperature luminescence intensity. Therefore, Dy3+, Li+ co-doped Sr3-xGa2Ge4O14 phosphor is a potential candidate material for display devices and white light LED devices. [ABSTRACT FROM AUTHOR]

A new type of local resonance sandwich metastructure beam is proposed in this paper. The structure consists of the corrugated sandwich beam matrix and local resonance units which is composed of mass blocks wrapped by soft materials. The band gap distribution and vibration transmission characteristics of the structure are calculated by transfer matrix method and finite element method respectively. The vibration transmission test platform of the sandwich metastructure beam was built, and the test data were obtained and compared with the calculation results. Finally, the regulation strategy of the structural parameters on the band gap characteristics of the structure was studied. The results show that: there are two flexure wave band gaps in the low frequency range, and the band gap frequencies are 196. 1 ~ 339. 0 Hz and 377. 2 ~ 655. 6 Hz, respectively; a full band gap is shown in the flexure wave band gaps, and the frequency range is 380. 0 ~ 423. 6 Hz. Within these two band gap ranges, significant suppression of flexure vibration transmission occurs. The structural parameters of corrugated sandwich beams have great influence on the characteristics of the band gaps. The low frequency and high bandwidth vibration reduction requirements of the local resonance sandwich metastructure beam can be realized by selecting proper structural parameters. [ABSTRACT FROM AUTHOR]

In recent years, antimonide infrared technology has developed rapidly and has become one of the important development directions of semiconductor technology. Gallium antimonide (GaSb), as a typical III-V compound semiconductor, has become a key substrate material for antimonide infrared optoelectronics due to its excellent properties. The demand for GaSb wafers is increasing, and higher requirements are also put forward with the maturing and application of antimonide infrared technology. The properties of epitaxial materials and devices are directly affected by substrate quality, so that GaSb substrates are required to have the characteristics of large size, lower defect density, better surface quality and consistency. The properties, growth methods, research progress at home and abroad, as well as applications of GaSb crystal are reviewed in this paper, and the development prospects are also analyzed. [ABSTRACT FROM AUTHOR]

Nonlinear optical crystals are the core devices of all-solid-state lasers, and have extensive and important applications in information technology and national security. With the development of high-performance computing, the "top-down" computer-aided design methods have gradually become an important part of nonlinear optical materials design. In addition, the large-scale structural and properties information obtained based on high-throughput computing provides a solid data foundation for data mining and machine learning algorithm training, accelerating the development of the fourth paradigm of material design. This paper starts with the computational design of nonlinear optical materials, and then, discusses the new paradigm of data-driven nonlinear optical materials theoretical design. Finally, the recent research progress of our team in high-throughput screening, crystal structure prediction, and machine learning accelerated nonlinear optical materials are reviewed. [ABSTRACT FROM AUTHOR]

The growth cycle of tellurium zinc cadmium crystals is long and the growth system is complex. When using vertical Bridgman or vertical gradient freezing methods to grow tellurium zinc cadmium (CdZnTe) crystal materials, the growth process is often difficult to observe intuitively, and there is no corresponding means to detect the temperature field inside the crystals, which brings inconvenience to improve the crystal growth process. In this paper, numerical simulation software is used to analyze the influences of furnace air convection on the temperature field of CdZnTe crystal growth. By opening holes at the top and bottom of furnace, gas exchanging occurs between the inside and outside of the furnace, thereby regulates the convection behaviors. Before opening holes, the convection rate is slow (only 10-5 m/s), forming stable convection cells; after opening holes, the convection rate significantly increases (0.25 - 0.90 m/s), and the convection state changes to laminar flow. Through controlling the aperture size (20 - 40 mm) in the model, the laminar flow rate can be effectively regulated. At the same temperature setting, when the flow rate increases from 0.25 m/s to 0.90 m/s, the temperature gradient will increase from 0.5 K/mm to 1.1 K/mm. Furthermore, experimental work is applied on real furnace, the change of temperature filed before and after opening holes were studied. The experimental results of temperature gradient is accord with the simulating results. It is also found that under laminar flow state, increasing convection rate may improve the stability of temperature field. The increase of temperature gradient and the improvement of stability in the temperature field will be beneficial for the preparation of high-quality CdZnTe crystals. [ABSTRACT FROM AUTHOR]

In recent years, semiconductor devices are developing towards high heat dissipation, high breakdown field strength and low energy consumption, so the ultra-wide band semiconductor material β-Ga2 O3 has a broad application prospect. However, effective doping is the basis for realizing β-Ga2 O3 devices. In this paper, Ga2O3/Al/Ga2O3/Al/Ga2O3 composite structure is experimentally prepared by magnetron sputtering, and the Al atoms are thermally diffused into the film by high-temperature annealing at the same time, so as to form Al-doped β-Ga2O3 thin film. Then, the laser zone melting method was used to melt and recrystallize the film area to further enhance the doping quality. The Al-doped β-Ga2O3 thin films were tested and characterized in terms of crystal properties, impurity content and optical properties. The experimental results show that: Al doping basically does not change the crystal structure of β-Ga2O3 thin films; the impurity content is gradually enhanced as the sputtering time of the Al layer becomes longer; in terms of the optical properties, the ultraviolet (UV) absorptivity of the films is 40% and 50% when the Al sputtering time is 5 and 10 s, and the UV absorption of the Al-doped β-Ga2O3 thin films is gradually enhanced with the increase of Al sputtering time; the light absorption of β-Ga2O3 thin film is close to 90% when the Al sputtering time is 300 s; and the low concentration of Al doping leads to the narrowing of the band gap width of β-Ga2O3 thin film. [ABSTRACT FROM AUTHOR]

Due to their unique physical and chemical properties, wide bandgap semiconductor materials have shown great potential in the field of optoelectronic devices, and have received more and more research and attention. Zinc gallate (ZnGa2O4) is a wide bandgap semiconductor material, showing broad application prospects in the fields of solar-blind ultraviolet photoelectric detection and X-ray detection for its wide bandgap, unique structure and good thermal stability. In this paper, based on the basic structural characteristics of ZnGa2O4, the bandgap, photoelectric properties of ZnGa2 O4, the preparation methods of ZnGa2O4 bulk single crystal and thin film are introduced in detail. Combined with the recent research results of domestic and foreign scholars, the application prospects of ZnGa2 O4 in many fields are summarized, especially the research progress of solar-blind ultraviolet photoelectric detection, memristor, X-ray detection and power devices. Finally, the future development direction of ZnGa2O4 is prospected, and it is pointed out that the quality and performance of ZnGa2O4materials can be further improved to improve device performance and meet higher level application requirements. [ABSTRACT FROM AUTHOR]