双层钙钛矿Sr_2TiMnO_6的溶胶–凝胶法合成和介电性研究

Synthesis of the double-layered perovskite Sr_2TiMnO_6by sol-gel method and study of dielectric properties

采用溶胶-凝胶法制备了Sr2TiMnO6陶瓷粉末，利用X射线衍射、红外光谱、扫描电子显微镜对其结构进行了表征，并研究了Sr2TiMnO6的介电行为。结果表明，煅烧温度为1473K时即可合成具有四方结构的双层钙钛矿Sr2TiMnO6，且样品结晶性良好。在125～475K时材料的介电行为表现出频率弥散现象并出现两处介电弛豫。低温介电弛豫满足Arrhenius公式，表明该弛豫行为由热激活引起；而在高温下，材料缺陷（气孔）及大的漏导导致介电损耗迅速增大。

The ceramic powder Sr2TiMnO6 was prepared by sol-gel method. The structure of the prepared Sr2TiMnO6 was investigated by X-ray diffraction, infrared spectrum and scanning electron microscope, and its dielectric properties were also discussed. The results show that double-layered perovskite Sr2TiMnO6 with tetragonal structure can be synthesized and well crystallized at the calcination temperature of 1 473 K. Dielectric behavior of Sr2TiMnO6 shows strong frequency dispersion phenomena between 125 K and 475 K, accompanied by two dielectric relaxation. Low temperature dielectric relaxation, fitted with Arrhenius formula, is induced by thermal activation. At higher temperature, dielectric loss increases rapidly due to material defects （such as pores） and its semiconductor properties.