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。
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 microstruc-ture 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 fre-quency 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 ad-dition, is attributed to the intrinsic electronic relaxation. Energy level 2 decreased from 0.50 eV to 0.22 eV with in-creased 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.
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