ZnO-B2O3对CaCu3Ti4O12陶瓷结构和介电性能的影响

摘要

采用传统固相反应法,将ZnO-B2O3(ZB)与1 100℃预烧的CaCu3Ti4Ol2(CCTO)粉末混合烧结成陶瓷.探讨ZB对CCTO陶瓷显微结构和介电性能的影响,并进一步分析CCTO陶瓷的巨介电机理.结果表明:当添加少量ZB(w≤2%,质量分数)时,形成体心立方BCC类钙钛矿结构的CCTO单相;当w>2%时,生成Zn2TiO4杂相;当ZB的添加量为0.5%和10%时,CCTO陶瓷的介电常数明显增大,介电损耗也较高;而当ZB的添加量为1.0%～5.0%时,介电常数的变化很小,同时具有较低的损耗和良好的温度稳定性.其中,w=2%时CCTO基陶瓷具有优异的介电性能(100kHz),即相对介电常数εr=336,介电损耗tanδ=0.018,介电常数温度系数τs=-1.5×10-5℃-.ZB掺杂CCTO基陶瓷的阻抗谱表明:CCTO陶瓷由半导体化晶界和相对绝缘的晶粒构成,因此,其具有巨介电常数.%ZnO-B2O3 (ZB) doped CaCu3Ti4O12 (CCTO) ceramics were prepared by solid-state reaction, from the mixture of ZB and CCTO powder calcined at 1 100 ℃.The effects of ZB on the microstructure and dielectric properties of CCTO ceramics were investigated.And the dielectric mechanism with giant dielectric constant was also analyzed.The results show that CCTO ceramics with a small amount of ZB additive (w≤2％, mass fraction) is of single CCTO phase with BCC perovskite structure.Zn2TiO4 phase is detected when w is above 2％.For the CCTO ceramics with w=0.5％and 10％, the dielectric constant is enhanced obviously, while the dielectric loss is higher than that of CCTO.On the other hand, for the CCTO ceramics with 1％-5％ ZB additions, the dielectric constant is nearly independent of ZB content and frequency.And they exhibit low dielectric loss and good thermal stability.Especially, CCTO ceramics with 2％ ZB exhibit the excellent dielectric properties: relative dielectric constant εr=336, dielectric loss tan δ=0.018, temperature coefficient of dielectric constant τε=-1.5 × 10-5 ℃-1.The impedance spectra of the ZB-doped CCTO ceramics indicate that CCTO ceramics consist of semiconducting grain boundaries and insulating grains, which results in the giantdielectric constant of CCTO ceramics.