中文摘要：

采用固相法制备了Ca_（1-x）Gdx_Cu_3Ti_4O_（12）（x=0～0.09）陶瓷系列样品,利用X射线衍射、Raman光谱和正电子湮没等技术手段,对系列样品的微观结构、缺陷浓度进行测试和表征。结果表明,在整个掺杂范围内体系未发生结构相变,掺杂引起体系晶格膨胀、分子极化率增加;随Gd掺杂量x的增加,空位型缺陷增加。电性能测试结果表明,适量Gd掺杂（x=0.01）有利于改善体系的压敏性能,而过量Gd掺杂（x=0.07～0.09）会阻碍晶界势垒的形成,因而抑制体系的压敏性能。讨论了体系微观结构、空位型缺陷浓度及晶界势垒高度等因素对体系压敏性能的影响特征。

英文摘要：

The CaCu_3Ti_4O_（12） ceramics doped with various Gd （χ=0-0.09） contents were fabricated by traditional solid-state method. X-ray diffraction, Raman spectroscopy and positron annihilation technique were employed to investigate the microstructure and defect concentration of Gd doped CCTO systems. The results show that no phase t transition occurs in the range of doping content, but the lattice expansion and increases of molecular polarizability are induced by Gd additives. The results also display that the vacancy-type defect increases with the increasing of Gd doping content. The electrical performances test show that the non-ohmic property is improved by adding an appropriate amount of Gd additives （χ=0.01） but weakened by higher Gd content （χ=0.07-0.09）. The influences of microstructure, vacancy-type defect concentration and the grain boundary barrier height on the non-ohmic properties were also discussed.