The structure and dielectric properties of bismuth-nickel-niobium oxide based ceramics

Bismuth-nickel-niobium oxide based ceramics have been prepared by conventional solid state reaction technique. The structure and dielectric properties in this ternary oxide system have been investigated by X-ray diffraction analyses and temperature dependences of dielectric constant and loss factor measured at a wide range of frequencies (1 kHz to 100 kHz). Along the Bi2O3:Nb2O5=1∶1 composition line, there exist main phase of cubic pyrochlore type structure, and some other impurity phases common to vast range of selected compositions. Besides the low temperature dielectric relaxation found in the liquid nitrogen temperatures, another dielectric loss peak occurs at higher temperature. The estimated activation energy is of approximately 0.50 eV, and can be related to the loss arising from conduction process of the impurities and the defects.