尖晶石型CuAl2O4掺杂对CaCu3Ti4O12陶瓷介电性能的影响

研究了尖晶石型CuAl₂O₄掺杂对CaCu₃Ti₄O₁₂陶瓷显微结构、介电性能以及松弛特征和缺陷结构的影响。在频率为10^-1~10⁷ Hz、温度为153~453 K的条件下测量了样品的介电性能。研究表明, 适量添加CuAl₂O₄, 使样品晶粒尺寸减小并趋于均匀, 击穿场强从CaCu₃Ti₄O₁₂陶瓷样品的3.0 kV/cm提高到13.0 kV/cm, 低频介电损耗减小。介电松弛中的高频松弛过程起源于晶粒本征缺陷的电子松弛过程, 其活化能~0.10 eV基本不变; 随着CuAl₂O₄含量增加, 与界面相关的松弛活化能从0.50 eV减小到0.22 eV, 可能与CuAl₂O₄在样品中引入杂质及更复杂的界面有关; 电导活化能从0.66 eV增至0.86 eV, 归因于CuAl₂O₄第二相抑制了晶界处的载流子跳跃, 提高了Schottky势垒高度。CuAl₂O₄掺杂量大于100mol%, 过量CuAl₂O₄会导致样品晶界势垒崩塌, 样品失去非欧姆特性和巨介电性能。

Influences of CuAl2O4 Doping on the Dielectric Properties of CaCu3Ti4O12 Ceramics

The influences of CuAl₂O₄ doping on the microstructure and dielectric relaxation of CaCu₃Ti₄O₁₂ (CCTO) ceramics were investigated. The dielectric properties were measured in the frequency from 10^-1 Hz to 10⁷ Hz under the temperature from 153 to 453 K. It was found that reduced CCTO grains as well as improved microstructure were achieved by addition of 30mol%-50mol% CuAl₂O₄. When sintered at 1100℃ for 4 h, enhanced electric breakdown field of 13 kV/cm was obtained with 50mol% CuAl₂O₄ addition, while its dielectric loss at low frequency was greatly suppressed. Three energy levels of dielectric relaxation processes were found. It is suggested that energy level 1 eV of ~0.10 eV, corresponding to high frequency relaxation and barely varied with CuAl₂O₄ addition, is attributed to the intrinsic electronic relaxation. Energy level 2 decreased from 0.50 eV to 0.22 eV with increased additional CuAl₂O₄, possibly resulted from multi impurities and boundaries. The energy level of conduction process rose from 0.66 eV to 0.86 eV with increased CuAl₂O₄ addition, which can be attributed to the block effect of more grain boundaries. In addition, the excessive content CuAl₂O₄ resulted in collapse of grain boundary barrier, leading to the vanish of non-ohmic properties and high dielectric constant.