Influences of CuAl_2O_4 doping on the dielectric properties of CaCu_3Ti_4O_(12) ceramics

摘要

The influences of CuAl_2O_4 doping on the mi-crostructure, dielectric properties and relaxations of CaCu_3Ti_4O_(12) ceramics have been studied in the paper. The dielectric properties were measured under the frequency from 10~(-1) to 10~7 Hz and the temperature from 153 to 453 K. An enhanced breakdown electric field, associated with lower dielectric loss at low frequency has been obtained via adding CuAl_2O_4. Three Dielectric relaxation processes are found in the frequency dependence of modulus planes. The activation energy of 0.10 eV, barely varies with CuAl_2O_4 addition, and is attributed to the intrinsic electronic relaxation. The energy level decreasing from 0.50 to 0.22 eV with the addition of CuAl_2O_4 may be caused by multi impurities and boundaries. The energy of conduction process varies from 0.66 to 0.86 eV, which showed elevated energy barrier for hopping of charge carriers and can be attributed to the blocking effect of more grain boundaries. The barriers at grain boundary of the samples collapsed with excessive content of CuAl_2O_4, which led to the absence of non-ohmic properties and high dielectric constant.