Characterization of dielectric relaxations in CaCu₃Ti₄O₁₂ via diverse complex planes: Effect of dipole polarization and dc conductivity

抄録

The physics of the dielectric relaxations induced by dipole polarization and dc conductivity are clarified via conjoint analysis of various complex planes. Taking CaCu₃Ti₄O₁₂ ceramic as a model sample, a typical dielectric relaxation induced by dipolar polarization is presented in the low-temperature range of 123–163 K. An obvious relaxation peak can be observed in dielectric permittivity and electric modulus planes, however, the relaxation peak gets blurred when characterized in impedance and conductivity planes because it is strongly covered by static permittivity or optical frequency permittivity effect. In the high-temperature range of 433–473 K, no evident relaxation is found in permittivity and conductivity planes, while a new dielectric relaxation process induced by dc conductivity arises in impedance and modulus planes. The activation energies of the low-temperature and high-temperature relaxation peaks are 0.094–0.097 and 0.92–0.93 eV, which corresponds to the bulk defect and grain boundary defect of the CaCu₃Ti₄O₁₂ ceramic, respectively.