Relaxations in Ba2BiTaO6 ceramics investigated by impedance and electric modulus spectroscopies

Highlights: ► We have confirmed that the relaxation observed in Ba2BiTaO6 is due to the conduction mechanism. ► The conduction mechanism is the oxygen vacancies hopping. ► We have explained because the activation energy for the Ba2BiTaO6 is lower than observed for Ba2BiSbO6 with basis in zero-point energy of both materials. ► We have showed that a minor secondary phase is a minor secondary phase, which is common when the BBTO is obtained by ceramic method under air, does not change significantly the electrical properties of BBTO. -- Abstract: Impedance spectroscopy analysis of the dielectric properties of a Ba2BiTaO6 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 Ba5Ta4O15 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 Ba2BiTaO6 is due to hopping of oxygen vacancies and that the impurities not influence the conduction mechanism.