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Characterization and Analysis of the Initial and Intermittent Growth Interfaces of MPCVD Single Crystal Diamond
LI Yicun, SHU Guoyang, LIU Gang, HAO Xiaobin, ZHAO Jiwen, ZHANG Sen, LIU Kang, CAO Wenxin, DAI Bing, YANG Lei, ZHU Jiaqi, CAO Kangli, and HAN Jiecai
Large-size and high-quality single crystal diamond synthesized by microwave plasma chemical vapor deposition (MPCVD) have excellent physical and chemical properties, which makes them have great application prospects in jewelry, electronics, nuclear and ray detection and other industry fields. During CVD single crystal Large-size and high-quality single crystal diamond synthesized by microwave plasma chemical vapor deposition (MPCVD) have excellent physical and chemical properties, which makes them have great application prospects in jewelry, electronics, nuclear and ray detection and other industry fields. During CVD single crystal diamond growth, it is found that there is an obvious interface between the substrate and the epitaxial layer, as well as between the multiple growth layers which stop-continue to grow. The interface region was analyzed by polarization microscope, Raman spectra and photoluminescence spectra(PL). The bright image under polarization microscope and higher content of NV color centers compared with substrate and its epitaxial layers indicate that the interface area has high defect and impurity content. The results show that some measures should be taken to control the quality of high-quality single crystal diamond at the initial stage, and the preparation should be completed in one growth cycle as far as possible..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1765 (2020)
HPHT Annealing of Boron and Nitrogen Co-Doped Diamond
CHEN Ning, ZHANG Guoqing, XU Gang, HUANG Guofeng, and ZHOU Zhenxiang
In this paper, boron and nitrogen co-doped diamond was synthesized under the condition of 5.5 GPa and 1 300 ℃ by temperature gradient growth method. Then the synthetic diamond was annealed under the pressure of 5.0 GPa and the temperature of 2 000 ℃ and 2 100 ℃. FT-IR spectra demonstrate that the singly substituted forIn this paper, boron and nitrogen co-doped diamond was synthesized under the condition of 5.5 GPa and 1 300 ℃ by temperature gradient growth method. Then the synthetic diamond was annealed under the pressure of 5.0 GPa and the temperature of 2 000 ℃ and 2 100 ℃. FT-IR spectra demonstrate that the singly substituted form nitrogen (C-center) in the crystal after high pressure and high temperature (HPHT) annealing is transformed into the aggregation form nitrogen (A-center), and the concentration of A-center nitrogen increases with the annealing temperature. The concentration of positively charged nitrogen ion (N+) in the crystal is not affected by HPHT annealing treatment. After high temperature annealing, NV0 and NV- center appear in the diamond, but disappear when the annealing temperature continues to increase. HPHT annealing has no obvious effect on the structure and internal stress of diamond crystal. After HPHT annealing treatment, the thermal stability of diamond is improved, the initial oxidation temperature, intense oxidation temperature and the temperature point where the mass sharply decrease are increased by 65 ℃, 55 ℃ and 61 ℃, respectively. This paper provides guidance for the HPHT annealing treatment application to boron and nitrogen co-doped diamond..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1770 (2020)
Growth of 70% DKDP Crystal by Directional Growth of Point Seed
HU Ziyu, ZHANG Min, LIN Xiuqin, QI Yingkun, LU Junye, LI Jingwen, and ZHENG Guozong
The rapid growth of KDP-type crystals mainly adopts the point seed rapid growth method. The three-dimensional point seed will inevitably lead to the pyramid-prism boundary, which affects the performance and quality of the crystals. In this paper, the traditional rapid growth of point seed method was improved by the desThe rapid growth of KDP-type crystals mainly adopts the point seed rapid growth method. The three-dimensional point seed will inevitably lead to the pyramid-prism boundary, which affects the performance and quality of the crystals. In this paper, the traditional rapid growth of point seed method was improved by the designed platform, and the 70% DKDP crystal was successfully grown by the directional growth of point seed. Avoiding the pyramid-prism boundary of the growing crystals, slices were taken, of which the deuterium content, transmittance, laser damage resistance and optical homogeneity were tested. The results show that the deuterium content of the crystals meets the design requirements, the transmittance and laser damage resistance of the crystals are consistent with those of the crystals grown by the traditional rapid growth of point seed. The results of optical homogeneity show that there is no pyramid-prism boundary in the slices, which will guide the growth of large diameter 70% DKDP crystal..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1776 (2020)
Band Gaps Characteristics of a Bending-Oriented Thermal Expansion Lattice Metamaterials
LIU Chenglong, XU Weikai, LYU Shuchen, and QI Wuchao
The current development of science and technology has put forward higher requirements for the versatility of materials. In this paper, a bending-oriented joint-bonded triangular cell lattice metamaterial (JTCLM) with triangular lattice was studied, and the influencce of geometrical parameters on the band gaps of JTCLM The current development of science and technology has put forward higher requirements for the versatility of materials. In this paper, a bending-oriented joint-bonded triangular cell lattice metamaterial (JTCLM) with triangular lattice was studied, and the influencce of geometrical parameters on the band gaps of JTCLM unit cell was discussed. The results show that the band gaps will be generated when the JTCLM cell has curved curvature, and the geometrical parameters of the microstructure have significant influence on the band gap of the JTCLM lattice composite. The results provide a theoretical basis for the design of metamaterials with binocular objects of thermal expansion and band gaps. Through reasonable material selection and shape design, it is expected to achieve a win-win situation with specific expansion properties and band gap design, so that the material has better tunability and versatility..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1782 (2020)
Epitaxial Growth Mechanism of SiC on the Vicinal Surface Simulated by Kinetic Monte Carlo
SHI Aihong, LI Yuan, and AI Wensen
A kinetic Monte Carlo model has been developed to study mechanism of growth patterns on 3C-SiC(111) vicinal surface. The growth temperature, deposition rate and terrace width have great influence on the growth mechanism of the vicinal surface. The simulation result show that many islands are nucleated on the vicinal suA kinetic Monte Carlo model has been developed to study mechanism of growth patterns on 3C-SiC(111) vicinal surface. The growth temperature, deposition rate and terrace width have great influence on the growth mechanism of the vicinal surface. The simulation result show that many islands are nucleated on the vicinal surface at low temperature and the crystal grows mainly by island nucleation. When the temperature increases, the islands are distribute in the edge of steps. As a result, the growth patterns are changed to mixed growth patterns. Secondly, the growth patterns are dominated by step flow growth at low deposition rate and two-dimensional nucleation growth regimes are dominated as the deposition rate increases. Finally, with the terrace width decreases adatoms preferentially attach to steps instead of nucleating new islands and the growth system crosses over from nucleation-dominated growth to step flow-dominated growth models..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1787 (2020)
Radiation Damage and Annealing Characteristics of Neutron-Irradiated 6H-SiC Single Crystals
HUANG Li, and RUAN Yongfeng
The lattice damage and annealing recovery of N-doped 6H-SiC under neutron irradiation with fluences of 1.72×1019 n/cm2 and 1.67×1020 n/cm2 was investigated by UV-Vis absorption spectroscopy. The results indicate that the significant increase of optical absorption and the decrease of band-gap energy in neutronThe lattice damage and annealing recovery of N-doped 6H-SiC under neutron irradiation with fluences of 1.72×1019 n/cm2 and 1.67×1020 n/cm2 was investigated by UV-Vis absorption spectroscopy. The results indicate that the significant increase of optical absorption and the decrease of band-gap energy in neutron-irradiated sample is assigned to localized energy level in the forbidden energy band induced by the accumulation of irradiated defects. A continuous strong absorption with many fine structures appeared near the band-edge after irradiation, the origin of which would be attributed to the presence of various different structures of defect clusters and localized amorphous zones. The irradiated samples with two fluences are isochronal annealed from room temperature to 1 600 ℃, the evolution of the absorption spectrum with the annealing temperature shows that the recovery temperature of the lattice damage for the irradiated sample with two fluences is different, but the annealing recovery process shows two same stages with 800 ℃ as the turning temperature..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1794 (2020)
Effect of Ti Content on the Properties of Ti and Ga Co-Doped ZnO Thin Films Prepared by Sol-Gel Method
WANG Rui, SUN Yihua, HUANG Long, AO Laiyuan, FANG Liang, and LUO Qiuzi
Nano-structured Ti and Ga co-doped ZnO (TGZO) thin films were synthesized with 1.0%(atomic fraction, the same below) Ga and different concentrations of Ti by sol-gel spin coating method. The influences of Ti doping concentration on the phase composition, surface morphology, electrical and optical properties of TGZO filNano-structured Ti and Ga co-doped ZnO (TGZO) thin films were synthesized with 1.0%(atomic fraction, the same below) Ga and different concentrations of Ti by sol-gel spin coating method. The influences of Ti doping concentration on the phase composition, surface morphology, electrical and optical properties of TGZO films were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis spectrophotometer, four point probes and Hall measurement system, respectively. The results show that all TGZO thin films exhibit polycrystalline with a hexagonal wurtzite structure and slight (002) preferred orientation, which show excellent transmittance (>86%) in the wavelength range between 380 nm to 780 nm. With the increase of Ti content, both the grain size and the average transmittance of visible light of the TGZO film increase first and then decrease, while the optical band gap and resistivity decrease and then increase. The highest visible light transmittance is 92.82%, the narrowest optical band gap is 3.249 eV and the lowest resistivity is 2.544×10-3 Ω·cm obtained when doping 1.0% Ti..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1800 (2020)
Comparative Study of Cu2ZnSnSe4 Thin Films Solar Cells Fabricated by Sputtering Selenide Targets and Metal Element Targets
LI Xiang, WANG Shurong, LIAO Hua, YANG Shuai, LI Xinyu, WANG Tingbao, LI Jingjin, LI Qiulian, and LIU Xin
Two kinds of Cu2ZnSnSe4(CZTSe) precursor layers were prepared by magnetron sputtering SnSe-ZnSe-Cu targets and metal Sn-Zn-Cu targets, respectively. The CZTSe absorber layers based on two kinds of precursors were prepared by using the same selenization process. The crystallization, phase purity, surface and section morTwo kinds of Cu2ZnSnSe4(CZTSe) precursor layers were prepared by magnetron sputtering SnSe-ZnSe-Cu targets and metal Sn-Zn-Cu targets, respectively. The CZTSe absorber layers based on two kinds of precursors were prepared by using the same selenization process. The crystallization, phase purity, surface and section morphology and elemental constituents of CZTSe film were investigated by X-ray diffraction (XRD), Raman microscopy(Raman), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), respectively. It was found that the CZTSe adsorption layer film with more flat and dense surface as well as without any obvious holes were obtained by sputtering selenide targets. The electrical properties of solar cell films were characterized by Hall system and J-V testing. The results show that the current density and conversion efficiency of the CZTSe solar cells based on selenide targets are higher than that of CZTSe solar cells from metal element targets. The CZTSe thin film solar cells based on metal element targets obtain a photoelectric conversion efficiency of 2.18% with an open circuit voltage of 356 mV and a short circuit current density of 20.61 mA/cm2, while the photoelectric conversion efficiency of CZTSe thin film solar cells prepared by selenide targets is 3.33% with an open circuit voltage of 354 mV and a short circuit current density of 28.41 mA/cm2..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1807 (2020)
Preparation of GdBa2Cu3O7-x Superconducting Films by Chemical Solution Deposition
HE Dong, TONG Liang, XU Wenbo, HU Wenpeng, CHENG Dawei, and XU Chongjian
Acetate was dissolved in propionic acid solution to prepare all fluorine-free GdBCO precursor solution. Afterwards, it is explored that the epitaxial growth of GdBa2Cu3O7-x(GdBCO) superconducting thin films on LaAlO3 (LAO)(100) single crystal substrates using all-fluoride-free chemical solution deposition (CSD) method.Acetate was dissolved in propionic acid solution to prepare all fluorine-free GdBCO precursor solution. Afterwards, it is explored that the epitaxial growth of GdBa2Cu3O7-x(GdBCO) superconducting thin films on LaAlO3 (LAO)(100) single crystal substrates using all-fluoride-free chemical solution deposition (CSD) method. The phases, orientation, morphology and superconducting property of the films synthesized at different annealing temperatures were studied. It is observed that GdBCO films manufactured at 817 ℃ have excellent biaxial orientations, and the Tc of the film annealed at 817 ℃ is 92.5 K, its critical current density (Jc) reaches 1.33 MA/cm2 at 77 K and self-magnetic field..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1814 (2020)
Ripening Behavior of Al Droplet on GaAs Surface
LI Ershi, HUANG Yanbin, GUO Xiang, WANG Yi, LUO Zijiang, LI Zhihong, JIANG Chong, and DING Zhao
To investigate the ripening behavior of Al droplets on GaAs surface, Al droplets were prepared onto GaAs substrates by droplet epitaxy. The growth and nucleation of Al droplets were effectively controlled by controlling the annealing time without arsenic pressure. By combining thermodynamic principles and crystal growtTo investigate the ripening behavior of Al droplets on GaAs surface, Al droplets were prepared onto GaAs substrates by droplet epitaxy. The growth and nucleation of Al droplets were effectively controlled by controlling the annealing time without arsenic pressure. By combining thermodynamic principles and crystal growth theories, physical explanation of the different sample morphology and constructed the basic models about ripening, etching and diffusion behaviors during the process of droplets morphology transition were carried out. The calculation results confirm that the droplet will be consumed by etching and diffusion process simultaneously when the ripening behavior reaches the equilibrium state after annealing of 239 s..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1819 (2020)
Hydrothermal Synthesis and Luminescent Properties of Eu3+,Tb3+ Co-Doped NaGd(WO4)2 Phosphors with Tunable Color
ZHAI Yongqing, JIANG Longtai, DENG Derui, WANG Weiao, CHEN Xiangyun, and WU Han
A series of NaGd0.96-x(WO4)2∶0.04Tb3+,xEu3+(x=0, 0.005, 0.01, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18) phosphors were prepared by a relatively mild hydrothermal method without the addition of any template. The phase structure, morphology and particle size, and luminescence properties of the samples were inA series of NaGd0.96-x(WO4)2∶0.04Tb3+,xEu3+(x=0, 0.005, 0.01, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18) phosphors were prepared by a relatively mild hydrothermal method without the addition of any template. The phase structure, morphology and particle size, and luminescence properties of the samples were investigated by X-ray powder diffractometry (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometry, respectively. The results show that the as-synthesized samples are pure NaGd(WO4)2 with tetragonal scheelite structure, and possess defined square-plate morphology, uniform size distribution and good dispersity. All the samples can be excited effectively by near-ultraviolet light, and the emitting color can be tuned from green to red color by changing the doping concentration of Eu3+ and Tb3+..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1825 (2020)
Hydrothermal Self-Assembly Synthesis and CO2 Adsorption Property of Ordered Nitrogen-Doped Mesoporous Carbon
WAN Xia, XIAO Huining, and LIU Jie
Ordered nitrogen-doped mesoporous carbon CO2 adsorbents were synthesized by a simple one-step hydrothermal self-assembly method using F127 as a soft template, melamine and urea as the nitrogen source without additional pre-polymerization steps. Characterization methods including N2 adsorption/desorption, XRD, TEM, FT-IOrdered nitrogen-doped mesoporous carbon CO2 adsorbents were synthesized by a simple one-step hydrothermal self-assembly method using F127 as a soft template, melamine and urea as the nitrogen source without additional pre-polymerization steps. Characterization methods including N2 adsorption/desorption, XRD, TEM, FT-IR and XPS were taken to study the structure and surface properties of the adsorbents. Besides, the adsorption isotherms of CO2 and N2 on the ordered nitrogen-doped mesoporous carbon at different temperatures were determined, and the results were fitted and analyzed by various adsorption isotherm models (Langmuir, Freundlich, Temkin, Dual-site Langmuir (DSL) models), further combined with the IAST model, the CO2/N2 adsorption selectivity of adsorbents in simulated flue gas was predicted. The results indicate that the ordered nitrogen-doped mesoporous carbon exhibit large specific surface area (up to 498.6 m2/g), highly ordered mesostructure (P6mm space group) and high nitrogen content, and the nitrogen is uniformly doped in the carbon framework in various forms. It was found that the adsorption isotherms of CO2 and N2 on ordered nitrogen-doped mesoporous carbon were highly consistent with the DSL model. Moreover, NOMC-M with higher nitrogen content exhibit higher CO2 adsorption capacity (0 ℃, 3.55 mmol/g; 25 ℃, 2.67 mmol/g) and CO2/N2 adsorption selectivity(>40), and can still maintain good regeneration stability after continuous CO2 adsorption/desorption cycle test..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1831 (2020)
Preparation and Photocatalytic Antibacterial Property under Visible Light of Ag/g-C3N4 Nanosheets
LI Juan, ZHAO Dan, GUAN Shoujiang, LIU Xiangrong, XU Qiuyue, and MA Zhanqiang
On the basis of g-C3N4nanosheets prepared by liquid phase ultrasonic exfoliation, Ag/g-C3N4nanosheets were fabricated by loading Ag nanoparticles through the method of light reduction. The as-prepared samples were characterized by TEM, FT-IR, XRD, BET and transient photocurrent. The disinfection of Escherichia coli(E. On the basis of g-C3N4nanosheets prepared by liquid phase ultrasonic exfoliation, Ag/g-C3N4nanosheets were fabricated by loading Ag nanoparticles through the method of light reduction. The as-prepared samples were characterized by TEM, FT-IR, XRD, BET and transient photocurrent. The disinfection of Escherichia coli(E. coli) was studied to evaluate the photocatalytic activity under visible light. The photocatalytic antibacterial kinetics were researched by modified Hom model. The results show that 3% Ag/g-C3N4 nanosheets exhibit the optimal photocatalytic disinfection of E. coli and the k2 value of 3% Ag/g-C3N4 nanosheets is 2.99 times of bulk g-C3N4 and 1.45 times of 3% Ag/bulk g-C3N4. Large specific surface area and high photocarrier separation efficiency have resulted in the excellent photocatalytic antibacterial activity of 3% Ag/g-C3N4 nanosheets..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1841 (2020)
Effect of Reduction Nitriding Temperature on the Composition,Structure and Electrochemical Properties of Niobium Nitride Nanotubes
WANG Xuepei, HU Shilei, CUI Shuai, LYU Dongfeng, XU Jingyue, WEI Hengyong, CUI Yi, CHEN Yuejun, WEI Yingna, and BU Jinglong
The niobium nitride nanotubes were prepared on niobium foil by anodic oxidation combined with ammonia reduction nitridation. The effect of reduction nitriding temperature on the phase, morphology and electrochemical properties of the nanotubes were investigated by XRD, XPS, SEM and electrochemical measurements such as The niobium nitride nanotubes were prepared on niobium foil by anodic oxidation combined with ammonia reduction nitridation. The effect of reduction nitriding temperature on the phase, morphology and electrochemical properties of the nanotubes were investigated by XRD, XPS, SEM and electrochemical measurements such as CV, GCD and EIS. The results show that niobium nitride phase in the form of niobium oxide nitride appears after reduction nitriding. When the reduction nitriding temperature is 700 ℃, the structure of nanotube is uniform array. The inner diameter of the nanotube is about 35 nm, the thickness of the tube wall is about 12 nm, the length of the nanotube is about 1.5 μm. Therefore, the intrinsic impedance and charge transfer resistance of the sample are low, and the specific capacitance is 400 μF/cm2 as the current density is 0.1 mA/cm2..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1848 (2020)
Study on Formaldehyde Gas Detection Sensor Based on ZnO Nanowires in Building Environment
ZHANG Amei
In order to detect the formaldehyde content in building interiors, ZnO nanowire was used as the target for monitoring formaldehyde. ZnO nanowires were synthesized by hydrothermal method using zinc chloride (ZnCl2) and sodium citrate (C6H5Na3O7) as raw materials. The crystal structure and micromorphology of the preparedIn order to detect the formaldehyde content in building interiors, ZnO nanowire was used as the target for monitoring formaldehyde. ZnO nanowires were synthesized by hydrothermal method using zinc chloride (ZnCl2) and sodium citrate (C6H5Na3O7) as raw materials. The crystal structure and micromorphology of the prepared ZnO nanowires were analyzed by XRD, SEM and EDS. Structural characterization results show that the prepared ZnO nanowires have good crystallinity and high purity, with an average diameter of (39±10) nm, a length of about 400 nm, and good dispersion. As-prepared ZnO nanowires were brushed-coated on a ceramic tube, assembling into a gas sensor, and investigated systematic gas-sensing properties of sensor. The gas sensing test results show that the ZnO nanowire-based gas sensor has excellent gas-sensitivity properties to HCHO gas, and obtain a maximum sensitivity of 15.2 to 50×10-6 HCHO gas at the optimal working temperature of 125 ℃. In addition, it has good stability, reproducibility and selectivity..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1857 (2020)
Preparation and Property of Porous Carbonized Cotton Composite SnO2 Anode Material for Lithium-Ion Battery
GONG Keyu, ZHANG Tao, YAN Lei, GAO Feng, and MIAO Yang
The porous carbonized cotton structure was obtained by Mg2+ template method with absorbent cotton as raw material. The SnO2 particles were loaded on the surface and internal pores of the carbon fiber by hydrothermal method to obtain a composite material of porous carbonized cotton and SnO2 particles. The microscopic moThe porous carbonized cotton structure was obtained by Mg2+ template method with absorbent cotton as raw material. The SnO2 particles were loaded on the surface and internal pores of the carbon fiber by hydrothermal method to obtain a composite material of porous carbonized cotton and SnO2 particles. The microscopic morphology of the material were analyzed by scanning electron microscope (SEM), Raman spectroscopy and X-ray diffraction analysis (XRD). Its electrochemical performance as a negative electrode material for lithium-ion batteries were evaluated by cyclic voltammetry (CV) and electrochemical impedance (EIS) tests. The results show that the porous carbonized cotton structure loaded with SnO2 particles obtained by the Mg2+ template method can be used as the anode material, whose capacity remains at 500 mAh/g after 100 cycles at a current density of 300 mA/g. The composite material is a promising material for lithium-ion battery anode..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1863 (2020)
Improved Electrochemical Performance of Li1.2Ni0.2Mn0.6O2 Cathode Materials Synthesized by Freeze-Drying Assisted Sol-Gel Method
DUAN Wenjie, JIANG Youliang, LIU Saiqiu, LIAO Qijun, XIANG Yanhong, WU Xianwen, XIONG Lizhi, and HE Zeqiang
Li-rich Mn-based Li1.2Ni0.2Mn0.6O2 cathode materials were synthesized by freeze-drying assisted sol-gel method, and its structure, morphology, and electrochemical performance were compared with the same materials synthesized by traditional sol-gel method. XRD results show that the Li1.2Ni0.2Mn0.6O2 powders synthesized Li-rich Mn-based Li1.2Ni0.2Mn0.6O2 cathode materials were synthesized by freeze-drying assisted sol-gel method, and its structure, morphology, and electrochemical performance were compared with the same materials synthesized by traditional sol-gel method. XRD results show that the Li1.2Ni0.2Mn0.6O2 powders synthesized by freeze-drying assisted sol-gel method exhibit lower cation mixing, and the crystalline structure is improved by the presence of freeze-drying process. SEM images indicate that the extent of particle agglomeration of the materials synthesized by freeze-drying assisted sol-gel method is lower compared to the sol-gel sample. Electrochemical test results indicate that the materials synthesized by freeze-drying assisted sol-gel method exhibited better rate capability and cyclability. Besides, EIS results suggest that the charge transfer resistance of Li1.2Ni0.2Mn0.6O2 synthesized by freeze-drying assisted sol-gel method is much lower than that of the Li1.2Ni0.2Mn0.6O2 prepared by sol-gel method, which enhances the reaction kinetics..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1870 (2020)
Preparation and Electrochemical Properties of CNTs/SBS/PANI Composite Electrode Materials
NIU Lili
Carbon nanotubes(CNTs)/styrene butadiene styrene(SBS)/polyaniline(PANI) composite electrode materials were synthesized by in-situ polymerization in solution with ammonium persulfate as initiator and phytic acid as doping acid. The structure and morphology of the electrode materials were characterized by IR and SEM. TheCarbon nanotubes(CNTs)/styrene butadiene styrene(SBS)/polyaniline(PANI) composite electrode materials were synthesized by in-situ polymerization in solution with ammonium persulfate as initiator and phytic acid as doping acid. The structure and morphology of the electrode materials were characterized by IR and SEM. The electrochemical properties of the materials were characterized by CV, EIS and GCD. The results show that CNTs/SBS/PANI composite electrode materials have higher specific capacitance, cycle stability and rate performance than SBS/PANI composites. The maximum specific capacitance of CNTs/SBS/PANI composite electrode material is 356.7 F/g when the content of CNTs in aniline monomer is 3% and the scanning rate is 5 mV/s..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1877 (2020)
Optimization of the Output Characteristics and Structure of High Efficiency Solar Cells under Proton Irradiation
GE Xiaohan, and ZHANG Lei
The effect of the low energy (1.8 keV) proton radiation dose on the conversion efficiency of mono-crystalline silicon solar cells was analyzed in detail by TCAD semiconductor device simulation software. The relationship between the proton radiation dose and the recombination center density and trap density were given bThe effect of the low energy (1.8 keV) proton radiation dose on the conversion efficiency of mono-crystalline silicon solar cells was analyzed in detail by TCAD semiconductor device simulation software. The relationship between the proton radiation dose and the recombination center density and trap density were given by comparison of conversion efficiency and degradation characteristics. In the case of different proton radiation doses, the effects of front surface field (FSF) structure and front surface floating emitter (FFE) structure on short-circuit current density, open circuit voltage and conversion efficiency of solar cells were analyzed in detail, providing design basis for the front surface structure of solar cells under proton radiation. The simulation results show that the conversion efficiency of the solar cell is almost unchanged with the increase of the proton irradiation dose when the proton irradiation dose is less than 1×109 cm-2.When the proton irradiation dose is constant, there is the optimal doping concentration of FSF and FFE, which makes the solar cell conversion efficiency highest. When the proton irradiation doses are 0 cm-2 and 1×1010 cm-2, the peak conversion efficiency of the FFE structure is slightly lower than that of the FSF structure. When the proton irradiation dose is 1×1011 cm-2, the improvement effect of the FFE structure on the conversion efficiency of IBC solar cells is significantly better than that of the FSF structure..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1883 (2020)
Preparation and Surface Modification of SiC Quantum Dots by Controllable Chemical Etching Method
KANG Jie, SONG Yuepeng, SUN Weiyun, DING Ziyang, LI Lianrong, JIAO Can, and LEI Tengfei
Silicon carbide quantum dots (QDs) were prepared by controllable chemical etching method, and then the aqueous solution of SiC QDs were obtained by ultrasonic cavitation and high-speed chromatography, the surface physicochemical properties of SiC QDs were controlled by chemical coupling method. The microstructure and sSilicon carbide quantum dots (QDs) were prepared by controllable chemical etching method, and then the aqueous solution of SiC QDs were obtained by ultrasonic cavitation and high-speed chromatography, the surface physicochemical properties of SiC QDs were controlled by chemical coupling method. The microstructure and spectral properties of SiC QDs were characterized by adjusting the preparation parameters, the results show that the main factors affect the relative photoluminescence intensity of SiC QDs are corrosion times, composition of corrosive agent and corresive agent components. Adjusting the corrosion times and the proportion of corrosive agent components, then analysis pure sulfuric acid of coupling agent is added, the relative photoluminescence intensity of water-phase SiC quantum dots is the best when V(HF)∶V(HNO3)∶V(H2SO4)=6∶1∶1 is used to corrode the milled β-SiC powder. At the same time, the formation mechanism and modification stability of -SH on the surface of SiC quantum dots are studied and analyzed..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1889 (2020)
Simulation Optimization and Verification of a Microwave System for Microwave Plasma Chemical Vapor Deposition Device
WANG Xinyang, CAO Guangyu, and HUANG Chong
Microwave plasma chemical vapor deposition (MPCVD) is an important method for synthesis of high-quality diamond film due to its high plasma density, good controllability and high cleanliness in the deposition process. Based on the theory of resonant cavity and three-dimensional full-wave electromagnetic field simulatioMicrowave plasma chemical vapor deposition (MPCVD) is an important method for synthesis of high-quality diamond film due to its high plasma density, good controllability and high cleanliness in the deposition process. Based on the theory of resonant cavity and three-dimensional full-wave electromagnetic field simulation, the microwave plasma cavity, mode converter and substrate holder shapes, which have a great influence on microwave coupling efficiency and electric field distribution, were designed and optimized. By testing and monitoring the key parameters in the microwave transmission system, influence of the tuning variables on diamond deposition were analyzed. With the MPCVD device proposed in this paper, high quality diamond films were deposited with an effective circular growth area with a diameter of 50 mm at a growth rate of 10 μm/h to 25 μm/h. The characterization results show that the single crystal diamond films have optical transmittance close to theoretical threshold and an excellent crystalline structure, with low impurity contents of nitrogen and silicon..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1896 (2020)
Numerical Simulation of Influence of Graphite Crucible Thickness on Solar-Grade Polysilicon Prepared by Induction Heating
HAN Bo, LI Jin, and AN Baijun
Polycrystalline silicon prepared by the directional solidification method is currently the main photovoltaic raw material. During the preparation process, the thermal field structure and the control of the convection morphology of the silicon melt are extremely important for the growth of high-quality polycrystalline sPolycrystalline silicon prepared by the directional solidification method is currently the main photovoltaic raw material. During the preparation process, the thermal field structure and the control of the convection morphology of the silicon melt are extremely important for the growth of high-quality polycrystalline silicon. This article uses professional crystal growth software CGSim to prepare solar-grade polycrystalline silicon with vacuum. The graphite crucible in the induction casting furnace was improved and numerical simulation was carried out. The influence of the thickness of different graphite crucibles on the thermal field, flow field, solid-liquid interface, silicon crystal stress field, and V/G value was analyzed. The results show that when the thickness of the graphite crucible is 20 mm, good convection morphology, flat solid-liquid interface, reasonable V/G value, etc. can be obtained, which are beneficial to save the production cost of polysilicon and improve the quality of polysilicon. It provides an important theoretical basis for process optimization and defect aualysis in production practice..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1904 (2020)
Rheological Behavior and Slip Casting of Nano Y2O3 Aqueous Suspension
CHANG Yukun, WANG Tao, HE Jiao, ZHANG Xue, and LIAN Jingbao
Aqueous Y2O3 suspension was prepared by Y2O3 nano powders with a specific surface area of 18.1 m2/g as raw material and ammonium citrate (TAC) as dispersant, respectively. The influence of concentration of TAC, pH value, ball-milling time and solid loading on the rheological behavior of Y2O3 suspension was investigatedAqueous Y2O3 suspension was prepared by Y2O3 nano powders with a specific surface area of 18.1 m2/g as raw material and ammonium citrate (TAC) as dispersant, respectively. The influence of concentration of TAC, pH value, ball-milling time and solid loading on the rheological behavior of Y2O3 suspension was investigated. The results indicate that the stable and well-dispersed suspension with 2.2%(mass fraction) TAC and pH value in the range of 9.4 to 11.5 was achieved after 8 h ball-milling. The viscosity of the suspensions increases with increasing solid loading, and the green body of slip casting from 33%(volume fraction) suspension has the highest density. Compared with the traditional die pressing, more homogeneous powder particles in green bodies by slip casting are obtained..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1911 (2020)
Modeling and Analysis of Binding Strength of WC(0001)/TiN(111) Coating Interfaces for Different Atomic Stacks
XU Shaoli, ZHANG Suohuai, HOU Yiqun, and ZHU Mengjie
The bonding strength of WC(0001)/TiN(111) interface depends on the interface properties. The binding strength, interface energy, electronic structure and bonding of the WC(0001)/TiN(111) interface were investigated by first principles.The results show that: (1) for all interfaces, the order from large to small is C-HCPThe bonding strength of WC(0001)/TiN(111) interface depends on the interface properties. The binding strength, interface energy, electronic structure and bonding of the WC(0001)/TiN(111) interface were investigated by first principles.The results show that: (1) for all interfaces, the order from large to small is C-HCP-Ti(9.19 J/m2), W-OT-Ti( 4.28 J/m2) and W-OT-N( 2.98 J/m2). (2) the interface bonding mode of C-HCP-Ti is strong covalent bond, the binding strength of the two is the strongest. The bonding mode of W-OT-Ti interface are covalent bond and partial ionic bond, which are inferior to that of C-HCP-Ti interface binding strength. For W-OT-N, the interface binding strength is metallic bond, and the binding strength is relatively weak. (3) for these three types of interfaces, the interface energy of W-OT-Ti, W-OT-N and C-HCP-Ti in the whole ΔμC range can be negative, which indicate that these three interfaces have ultra-high stability..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1917 (2020)
Preparation and Characterization of Silica Coated Glauber’s Salt-Based Microencapsulated Phase Change Materials
WANG Yang, TIE Shengnian, DAI Xin, and HAO Baokang
Silica coated Glauber’s salt-based microcapsuled phase change materials were prepared by emulsion polymerization, using Tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) as the silicon source, Glauber’s salt-based microcapsuled phase change materials as core materials. The melting and solidifying enthalSilica coated Glauber’s salt-based microcapsuled phase change materials were prepared by emulsion polymerization, using Tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) as the silicon source, Glauber’s salt-based microcapsuled phase change materials as core materials. The melting and solidifying enthalpy of the microcapsules are measured as 136.4 J/g and 76.9 J/g, respectively, with associated temperatures of 23.6 ℃ and 17.6 ℃. The core-shell structure of the microcapsules reduces the degree of solid-liquid separation of inorganic hydrated salts and suppresses the occurrence of phase stratification. After 100 cycles, the enthalpy of melting is 64.3 J/g, which has good cycle stability and can be used in fields such as thermal energy storage..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1924 (2020)
Influence of Pb Excessive Value on the Synthesis of Perovskite PZT Antiferroelectric Ceramic Powder by Sol-Hydrothermal Method
HU Yanhua, YU Zhanjun, WANG Lixia, SONG Yan, and LEI Da
PZT antiferroelectric ceramic powder with single perovskite structure was synthesized by sol-hydrothermal method. According to the test results of the research group in the early stage, the hydrothermal reaction temperature was selected as 180 ℃, the hydrothermal reaction time as 24 h, and the concentration of mineraliPZT antiferroelectric ceramic powder with single perovskite structure was synthesized by sol-hydrothermal method. According to the test results of the research group in the early stage, the hydrothermal reaction temperature was selected as 180 ℃, the hydrothermal reaction time as 24 h, and the concentration of mineralizer KOH as 3 mol/L. The effects of the excessive value of Pb on the synthesis of PZT ceramic powder were discussed. It is found that the excessive value of Pb is too low to compensate for the loss of Pb in the reaction process. The loss of Pb at A position is easily lead to the decrease of the crystallinity of PZT powder and the incomplete crystallization of particles. With the increasing of Pb excessive value, the particle crystallization is enhanced and the crystallization is more complete. When the content of Pb increases to 10%, PZT powder with good crystallinity is obtained. Therefore, the best excessive value of Pb in this experiment is determined as 10%..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1930 (2020)
Modification of Anhydrous Calcium Sulfate Whiskers by Sodium Oleate and Its Mechanism
WANG Mingwei, CAO Jianxin, XIE Guiming, TIAN Shengcai, and TAO Shaocheng
Sodium oleate modified anhydrous calcium sulfate whiskers can not only enhance the hydrophobicity of anhydrite whiskers, but also introduce -C=C- groups on the surface of whiskers to increase its functionality. The influence of sodium oleate dosage, modification time and modification temperature on the modification effSodium oleate modified anhydrous calcium sulfate whiskers can not only enhance the hydrophobicity of anhydrite whiskers, but also introduce -C=C- groups on the surface of whiskers to increase its functionality. The influence of sodium oleate dosage, modification time and modification temperature on the modification effect was investigated by using the dispersion property of whisker in methyl methacrylate (MMA). The adsorption and modification mechanism of whiskers were explored by XRD, XPS and DRIFTS, the hydrophobicity of whiskers were determined by Washburn method. The results show that with the increase of sodium oleate dosage, the dispersion performance first becomes better and then becomes worse. When the mass ratio of sodium oleate to whisker is 1∶100, the settling height and settling velocity are greatly increased from 3.1 cm and 0.31 cm/min when the mass ratio of sodium oleate to whisker is 1∶200 to 10.6 cm and 1.06 cm/min, and the amount of sodium oleate when the dispersion performance starts to change suddenly increases with the temperature. DRIFTS show that oleate ions are mainly combined with calcium ions on the surface of the whiskers by physical adsorption and chemical adsorption, their characteristic absorption peaks are double peaks at 1 577 cm-1and 1 540 cm-1, and a single peak at 1 547 cm-1. The hydrophobicity of the modified whiskers is greatly increased compared with that before modification, and the contact angle with water increased from 0.04° before modification to 77.35° after modification..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1935 (2020)
Review on Recycling and Utilizing Processes of Ternary Cathode Materials in Spent Lithium-Ion Batteries
TAN Yi, MIAO Chang, NIE Yan, and XIAO Wei
Lithium-ion batteries are widely used in many fields because of the advantages of high energy density, excellent cycling performance, and low self-discharge rate. Nevertheless, the specific capacity of lithium-ion batteries cannot satisfy the practical demands further after being employed for 3 to 5 years due to the deLithium-ion batteries are widely used in many fields because of the advantages of high energy density, excellent cycling performance, and low self-discharge rate. Nevertheless, the specific capacity of lithium-ion batteries cannot satisfy the practical demands further after being employed for 3 to 5 years due to the decomposition of liquid electrolytes, which can lead to a large number of spent lithium-ion batteries undoubtedly. Therefore, recycling and utilizing of spent lithium-ion batteries reasonably can not only economize the resource, but also alleviate the environmental pollution. This paper summarizes the processing steps of spent lithium-ion batteries during the recycling process, which mainly consists of the pretreatment of ternary cathode materials, the leaching and separation of valuable metal ions and the regeneration of ternary cathode materials as well as comparing the advantages and disadvantages of various methods. On that basis, it is reasonable to move in a safe, environmental and efficient direction to recycle and utilize of ternary cathode materials in spent lithium-ion batteries..
Journal of Synthetic Crystals
- Publication Date: Jan. 09, 2021
- Vol. 49, Issue 10, 1944 (2020)