CeO_2掺杂对BaTiO_3系统微观结构及介电性能的影响

Effect of CeO_2 on the microstructure and dielectric properties of BaTiO_3 system

对稀土氧化物CeO2掺杂的BaTiO3系统微观结构和介电性能进行了研究。结果表明,在BaTiO3陶瓷中掺杂CeO2会产生细晶效应、介电常数增大以及介电损耗减小等现象。由X射线衍射仪(XRD)计算可知,c轴变长,a轴变短,增强Ti4+自发极化强度,因而介电常数有所提高。由于Ce4+离子进行A位取代,Ce4+离子半径(0.103 nm)小于Ba2+离子半径(0.135 nm),导致晶格常数有所减小,居里温度向低温移动。掺杂CeO2的摩尔分数为0.5%的BaTiO3陶瓷在1 240℃下烧成的主要性能指标为:室温介电常数ε25℃≈3 160,介电损耗≈0.9%,-55℃到125℃范围内最大电容量变化率不超过±15%。

The effects of rare earth oxides CeO2 on the microstructure and dielectric properties of BaTiO3 ceramic are elaborated in this paper. The results show that, the dielectric constant of this system increase greatly with the increasing content of CeO2. BaTiO3 ceramics doped with CeO2 produce fine grain effect,hence the dielectric constant increases and the dielectric loss decreases accordingly. It is calculated by XRD analysis that the crystal cell becomes longer in axis c and shorter in axis a. The self-polarization of Ti^4＋ is enhanced, so that dielectric constant increases. Ce^4 ＋（0. 103 nm ） substitutes for Ba^2 ＋ （0.135 nm） possessing smaller radius in A-site, so the crystal＇s geometrical symmetry decreases,which results in curie-temperature movement to low temperature. The dielectric materials could be sintered at 1 240℃ by doping 0.5% mol CeO2 additives into the BaTiO3 ceramics, and its excellent dielectric properties are achieved, with a dielectric constant at room temperature ~c about 3 160, dielectric loss about 0.9%and the temperature characteristics of the capacitance less than ±15% from -55℃ to 125℃.