Dielectric relaxation and electrical conduction in (BixNa1-x)0.94Ba0.06TiO3 ceramics

The dielectric relaxation and electrical conduction were investigated in (BixNa1-x)(0.94)Ba0.06TiO3 (Abb. xBNBT6, x = 0.5, 0.495, 0.485, and 0.475) ceramics prepared by solid state reaction. With a decrease in x, the dielectric properties of the ceramics decreased, whereas the electrical conduction increased, resulting in a transition from insulator to oxide-ions conductor. When x = 0.475, the ceramics exhibited large conductivity (similar to 10(-3) S cm(-1) at 575 degrees C) and low activation energy (similar to 0.45 eV), indicating their potential application in solid oxide fuel cells. A mixed conduction mechanism with oxide-ions, electrons, and holes was proposed. With a decrease in x from 0.495 to 0.475, it was found that the p-type conduction was switched to n-type conduction. The dielectric relaxation of the x = 0.495 sample was associated with short-range hopping of oxygen vacancies. However, the dielectric properties of the x = 0.485 and 0.475 samples can be explained by Maxwell-Wagner interface relaxation.