Effect of Sintering Temperature on Dielectric Properties of Hydrous Amorphous Zirconia

Abstract

The effect of sintering temperature on structural and dielectric properties of Hydrous Amorphous Zirconia (HAZ) synthesized through surfactant assisted chemical precipitation method is investigated. X-ray diffraction studies reveal that sintering temperatures greater than lowest crystallization temperature (500 °C) of HAZ caused an increase in lattice spacing resulting in monoclinic phase dominant ZrO2nanocrystals. The room temperature impedance measurement of pelletized hydrous amorphous zirconia powder sintered at 500 and 800°C is carried out in the frequency range of 40 HZ to 5 MHZ. From the impedance data, the dielectric constant, dielectric loss, loss tangent and AC conductivity of HAZ sintered at these temperatures are calculated. It is found that dielectric constant is higher for sample sintered at lower crystallization temperature due to higher tetragonal content. This is attributed to higher concentration of oxygen vacancies which results in large space charge polarization and high dielectric constant. Further the loss tangent curve indicates that mobility of charge carriers is decreased in HAZ sintered at higher temperature and hence the conductivity also decreases. However at higher frequency region, the dielectric constant of monoclinic zirconia is greater than tetragonal zirconia.