Orthorhombic HoMnO 3 films with a-axis orientations were prepared epitaxially on Nb-1.0wt%-doped SrTiO 3 single crystal substrates by using the pulsed laser deposition technique to fabricate all-oxide heterojunctions.X-ray diffraction and atomic force microscopy were then used to characterize the films.The temperature dependent current-voltage measurement displayed diode-like rectifying behavior,and the forward current was perfectly fitted using the thermionic emission model.The ideality factor and built-in potential were suggested.
ZHAO YuJie YUAN DeHua ZHANG LiXin DAI ZhenHong WANG WeiTian
Perovskite-structured barium strontium titanate[Ba_(1-x)Sr_(x)Ti O_(3),x=0.1–0.9] films have been epitaxially fabricated by using a pulsed-laser deposition technique.The third-order nonlinear optical properties were studied through a z-scan method,allowing the resolution of the nonlinear refractive and absorptive contributions to the responses.Although all the samples show almost the same value of nonlinear absorption coefficient,the extracted nonlinear refractive index of the sample of x=0.3 is apparently larger than that of other samples.Dependency of the nonlinear optical properties on the Ba/Sr ratio is discussed in terms of the crystal phase transformation and metal-oxygen bond length of the selected materials.
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.
