Stability and diffusion of chromium (Cr) in vanadium (V), the interaction of Cr with vacancies, and the ideal me- chanical properties of V are investigated by first-principles calculations. A single Cr atom is ene...Stability and diffusion of chromium (Cr) in vanadium (V), the interaction of Cr with vacancies, and the ideal me- chanical properties of V are investigated by first-principles calculations. A single Cr atom is energetically favored in the substitution site. Vacancy plays a key role in the trapping of Cr in V. A very strong binding exists between a single Cr atom and the vacancy with a binding energy of 5.03 eV. The first-principles computational tensile test (FPCTT) shows that the ideal tensile strength is 19.1 GPa at the strain of 18% along the [100] direction for the ideal V single crystal, while it decreases to 16.4 GPa at a strain of 12% when one impurity Cr atom is introduced in a 128-atom V supercell. For shear deformation along the most preferable { 110} (111) slip system in V, we found that one substitutional Cr atom can decrease the cleavage energy (7cl) and simultaneously increase the unstable stacking fault energy (]'us) in comparison with the ideal V case. The reduced ratio of ]'cl/]'us in comparison with pure V suggests that the presence of Cr can decrease the ductility of V.展开更多
Colloidal Au and poly(vinylpyrrolidone) (PVP) composite thin films are fabricated by spin-coating method. Linear optical absorption measurements of the Au/PVP composite films indicate an absorption peak around 530...Colloidal Au and poly(vinylpyrrolidone) (PVP) composite thin films are fabricated by spin-coating method. Linear optical absorption measurements of the Au/PVP composite films indicate an absorption peak around 530 nm due to the surface plasmon resonance of gold nanoparticles. Nonlinear optical properties are studied using standard Z-scan technique, and experimental results show large optical nonlinearities of the Au/PVP composite films. A large value of χ^(3)/α up to 0.56× 10-^10esu·cm is obtained, which is comparable to the best values reported in metal/oxlde composite films.展开更多
文摘模拟了氧化物多晶材料中晶粒和晶界的介电响应,分析了电阻和电容与阻抗谱之间的关系,利用阻抗谱斜率的关系来验证拟合数据的正确性.用高温固相反应法制备了钙钛矿氧化物材料HoMnO3,利用复阻抗分析谱分析了该材料在650 Hz~1 MHz频率范围内的介电响应,结果表明:制备的氧化物材料是由晶粒和晶界组成的多晶材料,并且高频部分反映HoMnO3材料晶粒行为;低频部分反映HoMnO3材料的晶界行为.通过数据拟合可以得到其晶粒和晶界的电阻分别约为105Ω和106Ω;晶粒和晶界的电容均约为10-9 F.
基金Project supported by the National Natural Science Foundation of China (Grant No.51061130558)the Natural Science Foundation of Shandong Province of China (Grant No.ZR2011AM014)
文摘Stability and diffusion of chromium (Cr) in vanadium (V), the interaction of Cr with vacancies, and the ideal me- chanical properties of V are investigated by first-principles calculations. A single Cr atom is energetically favored in the substitution site. Vacancy plays a key role in the trapping of Cr in V. A very strong binding exists between a single Cr atom and the vacancy with a binding energy of 5.03 eV. The first-principles computational tensile test (FPCTT) shows that the ideal tensile strength is 19.1 GPa at the strain of 18% along the [100] direction for the ideal V single crystal, while it decreases to 16.4 GPa at a strain of 12% when one impurity Cr atom is introduced in a 128-atom V supercell. For shear deformation along the most preferable { 110} (111) slip system in V, we found that one substitutional Cr atom can decrease the cleavage energy (7cl) and simultaneously increase the unstable stacking fault energy (]'us) in comparison with the ideal V case. The reduced ratio of ]'cl/]'us in comparison with pure V suggests that the presence of Cr can decrease the ductility of V.
文摘Colloidal Au and poly(vinylpyrrolidone) (PVP) composite thin films are fabricated by spin-coating method. Linear optical absorption measurements of the Au/PVP composite films indicate an absorption peak around 530 nm due to the surface plasmon resonance of gold nanoparticles. Nonlinear optical properties are studied using standard Z-scan technique, and experimental results show large optical nonlinearities of the Au/PVP composite films. A large value of χ^(3)/α up to 0.56× 10-^10esu·cm is obtained, which is comparable to the best values reported in metal/oxlde composite films.
文摘采用脉冲激光沉积(PLD)技术在MgO基片上制备了金属Fe薄膜.利用原子力显微镜研究了不同制备温度对薄膜表面形貌的影响.x射线衍射分析表明沉积温度大于500℃时,Fe薄膜在MgO基片上有很好的结晶性,并有单一取向.通过z扫描方法测量了超薄Fe膜的光学非线性,得到了Fe薄膜的非线性折射率n2=7.09×10-5cm2kW,非线性吸收系数β=-5.52×10-3cm W.