Relaxations in Ba 2BiTaO 6 ceramics investigated by impedance and electric modulus spectroscopies

Impedance spectroscopy analysis of the dielectric properties of a Ba 2BiTaO 6 ceramic was performed in the temperature range from room temperature to 500 K. The sample was prepared using conventional solid state synthesis under air and the X-ray diffraction shows the presence of Ba 5Ta 4O 15 as a minor secondary phase (0.09%). The impedance data clearly show contributions of the grain and grain boundary. The results indicate that the conduction in Ba 2BiTaO 6 is due to hopping of oxygen vacancies and that the impurities not influence the conduction mechanism. © 2011 Elsevier Ltd. All rights reserved