High-temperature dielectric properties of BaZr0.8Y0.2O3-δ ceramics

Ceramic samples of BaZr0.8Y0.2O3-δ (BZY) were synthesized by solution combustion based on the glycine nitrate process. The dielectric properties were investigated in the temperature range of 300-870 K and frequency range of 102-106 Hz. Two types of carriers, hydroxyl ions and oxygen vacancies, coexist in the material and lead to three sets of relaxations. The activation energies were calculated to be 0.50, 0.65, and 1.27 eV for low-, middle- and high-temperature relaxations, respectively. The low-temperature relaxation was ascribed to be a dipolar relaxation resulting from the OHO
- -Y dipole. The middle- and high-temperature relaxations were argued to be Maxwell-Wagner relaxations associated with space charges caused by hopping oxygen vacancies blocked by grain boundaries and sample-electrode contacts, respectively.