This paper carries out first principles calculation of the structure, electronic and optical properties of BexZn1-xO alloys based on the density-functional theory for the compositions x = 0.0, 0.25, 0.5, 0.75, 1.0. Th...This paper carries out first principles calculation of the structure, electronic and optical properties of BexZn1-xO alloys based on the density-functional theory for the compositions x = 0.0, 0.25, 0.5, 0.75, 1.0. The lattice constants deviations of alloys obey Vegard＇s law well. The BexZn1-xO alloys have the direct band gap （Г-Г） character, and the bowing coefficients axe less than the available theoretical values. Moreover, it investigates in detail the optical properties （dielectric functions, absorption spectrum and refractive index） of these ternary mixed crystals. The obtained results agree well with the available theoretical and experimental values.展开更多
The LiCoxNi1-xO2 （x=0.2, 0.5 and 0.8） cathode materials were synthesized by sintering the mixtures of lithium salt and CoxNi1-x（OH）2 （x=0.2, 0.5 and 0.8） which were achieved from corresponding CoxNi1-x alloys by...The LiCoxNi1-xO2 （x=0.2, 0.5 and 0.8） cathode materials were synthesized by sintering the mixtures of lithium salt and CoxNi1-x（OH）2 （x=0.2, 0.5 and 0.8） which were achieved from corresponding CoxNi1-x alloys by electrolysis technique. The structure and electrochemical characteristics of the obtained LiCoxNi1-xO2 were studied by XRD, SEM, PSCA and charge-discharge cycling test. The results show that the electrochemical capacities of the LiCoxNi1-xO2 （x=0.2, 0.5 and 0.8） materials are improved with the increase of the Ni content. The electrochemical performance of LiCo0.2Ni0.8O2 made in oxygen atmosphere has higher charge-discharge capacity and better cycleability compared with the one made in air atmosphere.展开更多
The energy band properties, density of states, and band alignment of the BexZn1-xO1-ySy alloy （Be- and S-doped wurtzite ZnO） are investigated by the first-principles method. BexZn1-xO1-ySy alloy is a direct band gap...The energy band properties, density of states, and band alignment of the BexZn1-xO1-ySy alloy （Be- and S-doped wurtzite ZnO） are investigated by the first-principles method. BexZn1-xO1-ySy alloy is a direct band gap semiconductor, the valence band maximum （VBM） and the conduction band minimum （CBM） of BexZn1-xO1-ySy are dominated by S 3p and Zn 4s states, respectively. The band gap and lattice constant of BexZn1-xO1-ySy alloy can be modulated by changing the doped content values x and y. With the increase in Be content value x in the BexZnl-xOl-ySy alloy, the band gap increases and the lattice constant reduces, but the situation is just the opposite when increasing the S content value y in the BexZn1-xO1-ySy alloy. Because the lattice constant of Be0.375Zn0.625O0.75S0.25 alloy is well matched with that of ZnO and its energy gap is large compared with that of ZnO, so the Be0.375Zn0.625O0.75S0.25 alloy is suitable for serving as the blocking material for a high-quality ZnO-based device.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10974139 and 10964002)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050610010)+1 种基金the Science-Technology Foundation of Guizhou Province of China (Grant Nos. [2009]2066,[2009]06 and [2010]2146)the Project of Aiding Elites’ Research Condition of Guizhou Province of China (Grant No. TZJF-2008-42)
文摘This paper carries out first principles calculation of the structure, electronic and optical properties of BexZn1-xO alloys based on the density-functional theory for the compositions x = 0.0, 0.25, 0.5, 0.75, 1.0. The lattice constants deviations of alloys obey Vegard＇s law well. The BexZn1-xO alloys have the direct band gap （Г-Г） character, and the bowing coefficients axe less than the available theoretical values. Moreover, it investigates in detail the optical properties （dielectric functions, absorption spectrum and refractive index） of these ternary mixed crystals. The obtained results agree well with the available theoretical and experimental values.
基金Project (2002CB211800) supported by the National Key Fundmental Research and Development Programof China
文摘The LiCoxNi1-xO2 （x=0.2, 0.5 and 0.8） cathode materials were synthesized by sintering the mixtures of lithium salt and CoxNi1-x（OH）2 （x=0.2, 0.5 and 0.8） which were achieved from corresponding CoxNi1-x alloys by electrolysis technique. The structure and electrochemical characteristics of the obtained LiCoxNi1-xO2 were studied by XRD, SEM, PSCA and charge-discharge cycling test. The results show that the electrochemical capacities of the LiCoxNi1-xO2 （x=0.2, 0.5 and 0.8） materials are improved with the increase of the Ni content. The electrochemical performance of LiCo0.2Ni0.8O2 made in oxygen atmosphere has higher charge-discharge capacity and better cycleability compared with the one made in air atmosphere.
基金supported by the National Natural Science Foundation of China(Grant No.61078046)the Special Funds for Provincial Strategic and Emerging Industries Projects of Guangdong Province,China(Grant No.2012A080304016)the Youth Foundation of South China Normal University,China(Grant No.2012KJ018)
文摘The energy band properties, density of states, and band alignment of the BexZn1-xO1-ySy alloy （Be- and S-doped wurtzite ZnO） are investigated by the first-principles method. BexZn1-xO1-ySy alloy is a direct band gap semiconductor, the valence band maximum （VBM） and the conduction band minimum （CBM） of BexZn1-xO1-ySy are dominated by S 3p and Zn 4s states, respectively. The band gap and lattice constant of BexZn1-xO1-ySy alloy can be modulated by changing the doped content values x and y. With the increase in Be content value x in the BexZnl-xOl-ySy alloy, the band gap increases and the lattice constant reduces, but the situation is just the opposite when increasing the S content value y in the BexZn1-xO1-ySy alloy. Because the lattice constant of Be0.375Zn0.625O0.75S0.25 alloy is well matched with that of ZnO and its energy gap is large compared with that of ZnO, so the Be0.375Zn0.625O0.75S0.25 alloy is suitable for serving as the blocking material for a high-quality ZnO-based device.
