Spin-polarized first-principle was performed to study the structural stability and the electronic states of Cr doped ZnS with the Cr component of 50% in zincblende （ZB）, wurtzite （W） and rocksalt （RS） structures...Spin-polarized first-principle was performed to study the structural stability and the electronic states of Cr doped ZnS with the Cr component of 50% in zincblende （ZB）, wurtzite （W） and rocksalt （RS） structures under pressure. The results show that the zincblende and wurtzite structures become unstable under low pressures of about 4.68 and 9.61 GPa, respectively, but the rocksalt structure can be maintained up to an extremely high pressure of about 32.92 GPa. Both zincblende and wurtzite Zno.sCro.5S display half metallic features under pressure, while rocksalt Zno.sCro.sS exhibits metallic feature. The half metallic features can be ascribed to the stronger interactions between S-3p and Cr-3d states and the metallic feature is due to the higher crystal symmetry of rocksalt Zn0.5Cr0.5S. These results can provide helpful guidance for Cr doped ZnS to be used in spintronic devices.展开更多
A chemical-assisted element direct-reaction method is developed to synthesize ZnSe compound semiconductor material at a relatively low temperature （-1000 ℃）. ZnSe polycrystal was obtained in the closed-tube systems...A chemical-assisted element direct-reaction method is developed to synthesize ZnSe compound semiconductor material at a relatively low temperature （-1000 ℃）. ZnSe polycrystal was obtained in the closed-tube systems with Zn-Se, Zn-Se-Zn（NHa）2CI2, ZnoSe-NH4CI and Zn-Se-ZnCI2. The as-synthesized samples were tested by X-ray diffraction （XRD）, thermogravimetric analysis （TGA） and analyzed by thermodynamic numerical method. The results demonstrate that the synthesis efficiency is higher than 99.96% for Zn-Se-ZnCl2 system at around 1000 ℃ for 3 weeks. It also exhibits that not only temperature, but also low apparent ratio of volume and surface area of the source materials and higher ZnCl2 content are required to achieve high synthesis efficiency. A SeCI transporting reaction synthesis process is proposed based on the thermodynamic analysis.展开更多
基金the financial support of the project from the National Natural Science Foundation of China (No. 11104175)the National Basic Research Program of China (No. 2011CB610406)+1 种基金the "111 Project" of China (No. B08040)the Research Fund of the State Key Laboratory of Solidification Processing, China
文摘Spin-polarized first-principle was performed to study the structural stability and the electronic states of Cr doped ZnS with the Cr component of 50% in zincblende （ZB）, wurtzite （W） and rocksalt （RS） structures under pressure. The results show that the zincblende and wurtzite structures become unstable under low pressures of about 4.68 and 9.61 GPa, respectively, but the rocksalt structure can be maintained up to an extremely high pressure of about 32.92 GPa. Both zincblende and wurtzite Zno.sCro.5S display half metallic features under pressure, while rocksalt Zno.sCro.sS exhibits metallic feature. The half metallic features can be ascribed to the stronger interactions between S-3p and Cr-3d states and the metallic feature is due to the higher crystal symmetry of rocksalt Zn0.5Cr0.5S. These results can provide helpful guidance for Cr doped ZnS to be used in spintronic devices.
基金supports of the National Natural Science Foundation of Chinathe National 973 Project (No. 2011CB610406)+1 种基金the Research Fund of Young Teachers for the Doctoral Program of Higher Education of China (No. 20106102120016)the Independent Subject of State Key Laboratory of Solidification Processing (74-QP-2011)
文摘A chemical-assisted element direct-reaction method is developed to synthesize ZnSe compound semiconductor material at a relatively low temperature （-1000 ℃）. ZnSe polycrystal was obtained in the closed-tube systems with Zn-Se, Zn-Se-Zn（NHa）2CI2, ZnoSe-NH4CI and Zn-Se-ZnCI2. The as-synthesized samples were tested by X-ray diffraction （XRD）, thermogravimetric analysis （TGA） and analyzed by thermodynamic numerical method. The results demonstrate that the synthesis efficiency is higher than 99.96% for Zn-Se-ZnCl2 system at around 1000 ℃ for 3 weeks. It also exhibits that not only temperature, but also low apparent ratio of volume and surface area of the source materials and higher ZnCl2 content are required to achieve high synthesis efficiency. A SeCI transporting reaction synthesis process is proposed based on the thermodynamic analysis.
