Lithium iron phosphate （LiFePO4） doped with magnesium was hydrothermally synthesized from commercial LiOH, FeSO4, H3PO4 and MgSO4 with glucose as carbon precursor in aqueous solution. The samples were characterized ...Lithium iron phosphate （LiFePO4） doped with magnesium was hydrothermally synthesized from commercial LiOH, FeSO4, H3PO4 and MgSO4 with glucose as carbon precursor in aqueous solution. The samples were characterized by X-ray powder diffraction, scanning electron microscopy and constant charge-discharge cycling. The results show that the synthesized powders have been in situ coated with carbon precursor produced from caramel reaction of glucose. At ambient temperature （28±2℃）, the electrochemical performances of LiFePO4 prepared exhibit the high discharge capacity of 135 mAh g^-1 at 5C and good capacity retention of 98% over 90 cycles. The excellent electrochemical performances should be correlated with the intimate contact between carbon and LiFePO4 primary and secondary particles, resulting from the in situ formation of carbon precursor/carbon, leading to the increase in conductivity of LiFePO4.展开更多
Mg-doped ZnO （MgxZn1-xO, x=0-0.10） nanoparticles were prepared by sol-gel method. Structural characterization by X-ray diffraction （XRD） indicates that the lattice parameter a increases and c decreases linearly wi...Mg-doped ZnO （MgxZn1-xO, x=0-0.10） nanoparticles were prepared by sol-gel method. Structural characterization by X-ray diffraction （XRD） indicates that the lattice parameter a increases and c decreases linearly with the increase in Mg content （x） due to the substitution of Mg2＋ for Zn2＋ in ZnO lattice. The blueshift of Raman modes is observed, impling the increase in force constant of atom vibration in the MgxZn1-xO （MgZnO） nanoparticles. Resonant Raman spectra show longitudinal optical phonon overtones up to fifth order, revealing that the short part of the electron-phonon interaction is enhanced and long-range part is weakened by Mg doping.展开更多
采用超软赝势密度泛函理论计算的方法研究了Mg掺杂Ca位CaMnO_3基复合氧化物的能带结构、电子态密度和电荷分布状况,在此基础上分析了Mg掺杂氧化物的电性能。结果表明,Mg掺杂CaMnO_3氧化物仍然呈间接带隙型能带结构,带隙宽度由0.756 e V...采用超软赝势密度泛函理论计算的方法研究了Mg掺杂Ca位CaMnO_3基复合氧化物的能带结构、电子态密度和电荷分布状况,在此基础上分析了Mg掺杂氧化物的电性能。结果表明,Mg掺杂CaMnO_3氧化物仍然呈间接带隙型能带结构,带隙宽度由0.756 e V减小到0.734 e V。CaMnO_3氧化物和Mg掺杂CaMnO_3氧化物的自旋态密度曲线极值点均位于为-0.8 e V附近。Mg掺杂CaMnO_3氧化物中Mn原子对体系费米面态密度的贡献有所减小,O原子和Ca原子对体系费米面态密度的贡献有所增大。Mg原子比Ca原子具有更强的释放电子的能力,Mg掺杂对于CaMnO_3氧化物属于电子型掺杂。Mg掺杂CaMnO_3氧化物导电性能增强,电性能提高。展开更多
Gallium nitride (GaN) and indium-gallium nitride (InxGa1-xN) thin films were directly grown on several non-single-crystalline substrates such as quartz glass and amorphous-carbon-coated graphite. The films were grown ...Gallium nitride (GaN) and indium-gallium nitride (InxGa1-xN) thin films were directly grown on several non-single-crystalline substrates such as quartz glass and amorphous-carbon-coated graphite. The films were grown by using a molecular beam epitaxy apparatus having single or dual nitrogen radio-frequency plasma cells, and in addition, germanium (Ge) or magnesium (Mg) doping to the films was also attempted. Crystallinity, photoluminescence (PL) property, and electrical property of the obtained films were investigated. Highly c-axis oriented GaN and InxGa1-xN thin films were obtained on the non-single-crystalline substrates. Near-band-edge emissions were observed in their PL spectra and the intensities were strongly enhanced by Ge doping. Ge doping was also effective on reducing resistivity of the GaN thin films grown on the non-single-crystalline substrates. Electrochemical capacitance-voltage measurements were carried out on the Mg-doped GaN thin films;and p-type conduction in the films was confirmed.展开更多
We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction（TJ） with using tellurium（Te） and magnesium（Mg） as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecu...We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction（TJ） with using tellurium（Te） and magnesium（Mg） as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecular beam epitaxy（MBE） at low temperature. The test Te/Mg-doped GaAs TJ shows a peak current density of 21 A/cm2. The tandem solar cell by the Te/Mg TJ shows a short-circuit current density of 12 m A/cm2, but a low open-circuit voltage range of1.4 V^1.71 V under AM1.5 illumination. The secondary ion mass spectroscopy（SIMS） analysis reveals that the Te doping is unexpectedly high and its doping profile extends to the Mg doping region, thus possibly resulting in a less abrupt junction with no tunneling carriers effectively. Furthermore, the tunneling interface shifts from the intended Ga As n＋＋/p＋＋junction to the AlGaInP/GaAs junction with a higher bandgap AlGaInP tunneling layers, thereby reducing the tunneling peak. The Te concentration of ~ 2.5 × 1020 in GaAs could cause a lattice strain of 10-3 in magnitude and thus a surface roughening,which also negatively influences the subsequent growth of the top subcell and the GaAs contacting layers. The doping features of Te and Mg are discussed to understand the photovoltaic response of the studied tandem cell.展开更多
以氨水和NaO H为络合剂和沉淀剂,采用氢氧化物共沉淀法合成了锂离子电池正极材料Li1.17Mn0.48Ni0.23Co0.12-MgxO2(x=0,0.01,0.02,0.03,0.05)。并利用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)和电化学测试对其晶体结构、形貌和电化...以氨水和NaO H为络合剂和沉淀剂,采用氢氧化物共沉淀法合成了锂离子电池正极材料Li1.17Mn0.48Ni0.23Co0.12-MgxO2(x=0,0.01,0.02,0.03,0.05)。并利用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)和电化学测试对其晶体结构、形貌和电化学性能进行了表征。研究表明:掺杂适量的Mg能够降低材料的阳离子混排度,改善材料的循环性能。Li1.17Mn0.48Ni0.23Co0.12Mg0.03O2具有最优的电化学性能,在0.1 C(1 C=358 mA h/g)下首次放电比容量为234.7 mA h/g,在0.1 C下循环10次后容量保持率为99.3%。展开更多
文摘Lithium iron phosphate （LiFePO4） doped with magnesium was hydrothermally synthesized from commercial LiOH, FeSO4, H3PO4 and MgSO4 with glucose as carbon precursor in aqueous solution. The samples were characterized by X-ray powder diffraction, scanning electron microscopy and constant charge-discharge cycling. The results show that the synthesized powders have been in situ coated with carbon precursor produced from caramel reaction of glucose. At ambient temperature （28±2℃）, the electrochemical performances of LiFePO4 prepared exhibit the high discharge capacity of 135 mAh g^-1 at 5C and good capacity retention of 98% over 90 cycles. The excellent electrochemical performances should be correlated with the intimate contact between carbon and LiFePO4 primary and secondary particles, resulting from the in situ formation of carbon precursor/carbon, leading to the increase in conductivity of LiFePO4.
基金financially supported by the National Natural Science Foundation of China (Nos. 11174001 and 11174002)the Science Foundation of Anhui Education (Nos. KJ2013A030)the Scientific Research Startup Outlay for Doctors in Anhui University
文摘Mg-doped ZnO （MgxZn1-xO, x=0-0.10） nanoparticles were prepared by sol-gel method. Structural characterization by X-ray diffraction （XRD） indicates that the lattice parameter a increases and c decreases linearly with the increase in Mg content （x） due to the substitution of Mg2＋ for Zn2＋ in ZnO lattice. The blueshift of Raman modes is observed, impling the increase in force constant of atom vibration in the MgxZn1-xO （MgZnO） nanoparticles. Resonant Raman spectra show longitudinal optical phonon overtones up to fifth order, revealing that the short part of the electron-phonon interaction is enhanced and long-range part is weakened by Mg doping.
文摘采用超软赝势密度泛函理论计算的方法研究了Mg掺杂Ca位CaMnO_3基复合氧化物的能带结构、电子态密度和电荷分布状况,在此基础上分析了Mg掺杂氧化物的电性能。结果表明,Mg掺杂CaMnO_3氧化物仍然呈间接带隙型能带结构,带隙宽度由0.756 e V减小到0.734 e V。CaMnO_3氧化物和Mg掺杂CaMnO_3氧化物的自旋态密度曲线极值点均位于为-0.8 e V附近。Mg掺杂CaMnO_3氧化物中Mn原子对体系费米面态密度的贡献有所减小,O原子和Ca原子对体系费米面态密度的贡献有所增大。Mg原子比Ca原子具有更强的释放电子的能力,Mg掺杂对于CaMnO_3氧化物属于电子型掺杂。Mg掺杂CaMnO_3氧化物导电性能增强,电性能提高。
文摘Gallium nitride (GaN) and indium-gallium nitride (InxGa1-xN) thin films were directly grown on several non-single-crystalline substrates such as quartz glass and amorphous-carbon-coated graphite. The films were grown by using a molecular beam epitaxy apparatus having single or dual nitrogen radio-frequency plasma cells, and in addition, germanium (Ge) or magnesium (Mg) doping to the films was also attempted. Crystallinity, photoluminescence (PL) property, and electrical property of the obtained films were investigated. Highly c-axis oriented GaN and InxGa1-xN thin films were obtained on the non-single-crystalline substrates. Near-band-edge emissions were observed in their PL spectra and the intensities were strongly enhanced by Ge doping. Ge doping was also effective on reducing resistivity of the GaN thin films grown on the non-single-crystalline substrates. Electrochemical capacitance-voltage measurements were carried out on the Mg-doped GaN thin films;and p-type conduction in the films was confirmed.
基金Project supported by the SINANO-SONY Joint Program(Grant No.Y1AAQ11001)the National Natural Science Foundation of China(Grant No.61274134)+1 种基金the USCB Start-up Program(Grant No.06105033)the International Cooperation Projects of Suzhou City,China(Grant No.SH201215)
文摘We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction（TJ） with using tellurium（Te） and magnesium（Mg） as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecular beam epitaxy（MBE） at low temperature. The test Te/Mg-doped GaAs TJ shows a peak current density of 21 A/cm2. The tandem solar cell by the Te/Mg TJ shows a short-circuit current density of 12 m A/cm2, but a low open-circuit voltage range of1.4 V^1.71 V under AM1.5 illumination. The secondary ion mass spectroscopy（SIMS） analysis reveals that the Te doping is unexpectedly high and its doping profile extends to the Mg doping region, thus possibly resulting in a less abrupt junction with no tunneling carriers effectively. Furthermore, the tunneling interface shifts from the intended Ga As n＋＋/p＋＋junction to the AlGaInP/GaAs junction with a higher bandgap AlGaInP tunneling layers, thereby reducing the tunneling peak. The Te concentration of ~ 2.5 × 1020 in GaAs could cause a lattice strain of 10-3 in magnitude and thus a surface roughening,which also negatively influences the subsequent growth of the top subcell and the GaAs contacting layers. The doping features of Te and Mg are discussed to understand the photovoltaic response of the studied tandem cell.
文摘以氨水和NaO H为络合剂和沉淀剂,采用氢氧化物共沉淀法合成了锂离子电池正极材料Li1.17Mn0.48Ni0.23Co0.12-MgxO2(x=0,0.01,0.02,0.03,0.05)。并利用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)和电化学测试对其晶体结构、形貌和电化学性能进行了表征。研究表明:掺杂适量的Mg能够降低材料的阳离子混排度,改善材料的循环性能。Li1.17Mn0.48Ni0.23Co0.12Mg0.03O2具有最优的电化学性能,在0.1 C(1 C=358 mA h/g)下首次放电比容量为234.7 mA h/g,在0.1 C下循环10次后容量保持率为99.3%。
