Influences of CuAl₂O₄ doping on the dielectric properties of CaCu₃Ti₄O₁₂ ceramics

The influences of CuAl₂O₄ doping on the microstructure, dielectric properties and relaxations of CaCu₃Ti₄O₁₂ ceramics have been studied in the paper. The dielectric properties were measured under the frequency from 10⁻¹ to 10⁷ 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 CuAl₂O₄. Three Dielectric relaxation processes are found in the frequency dependence of modulus planes. The activation energy of 0.10 eV, barely varies with CuAl₂O₄ addition, and is attributed to the intrinsic electronic relaxation. The energy level decreasing from 0.50 to 0.22 eV with the addition of CuAl₂O₄ 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 CuAl₂O₄, which led to the absence of non-ohmic properties and high dielectric constant.