【摘要】 采用固相法制备了偏离化学计量的CCTO陶瓷样品(组成Ca Cu3+xTi4O12,x=–0.12~+0.12),研究发现Cu含量的改变对微观结构和介电性能影响显著。符合化学计量比的Ca Cu3Ti4O12(CCTO)陶瓷微观结构不均匀,部分晶粒发生异常生长,而CCTO晶粒间界存在明显的富Cu相析出。随着Cu含量减少,晶粒平均粒径减小并趋于均匀。电性能测试结果表明,标准化学计量或Cu过量(x=0~0.12)的CCTO陶瓷样品,表观介电系数、压敏电压与样品厚度的关系符合体型或晶界型特征,即表观介电系数与样品厚度无关,压敏电压与样品厚度成正比;减少Cu含量(x=0~–0.12),这种体型或晶界型特征逐渐转变为表面型特征,当x<–0.08时,样品的表观介电系数与样品厚度成正比,压敏电压与样品厚度无关,表现出表面效应特征。更多还原

【Abstract】 CCTO ceramics with deviation from stoichiometry(composition CaCu₃Ti₄O₁₂, x= –0.12⁺0.12) were prepared by a traditional solid-state reaction process. It is found that the variation of Cu content has a significant effect on the microstructure and dielectric properties of samples. Stoichiometric CaCu₃Ti₄O₁₂ ceramics show a non-uniform microstructure with some abnormal growth grains and obvious intergranular Cu-rich phase. The average grain size decreases and becomes uniform with the reduction of Cu content. The results of electrical tests show the correlation between the apparent dielectric constant, the breakdown voltage of stoichiometric or Cu-excessive（x=0⁺0.12） samples and the sample thickness conforms to bulk or grain boundary characteristics, namely the apparent dielectric coefficient is independent of the sample thickness and the breakdown voltage is proportional to the thickness of the sample. With the reduction of Cu content（x=0^–0.12）, this bulk or grain boundary characteristics gradually transform into surface-type characteristics. When x<–0.08, the apparent dielectric constant is proportional to the sample thickness and the breakdown voltage is independent of the sample thickness, exhibiting characteristics of surface effects.更多还原