Na0.5Bi0.5Cu3Ti4O12 nanocrystalline powders prepared by a glycine–nitrate process: Preparation, characterization, and their dielectric properties

Abstract

Na0.5Bi0.5Cu3Ti4O12 nanocrystalline powders were prepared by a combustion method using glycine as a fuel. X-ray diffraction technique was used to characterize Na0.5Bi0.5Cu3Ti4O12 nanocrystalline powders, which were obtained by firing precursors at 800–900°C for 6h. Dense ceramic microstructure of Na0.5Bi0.5Cu3Ti4O12 was obtained by sintering ceramic powders at 980°C for 12h. The Na0.5Bi0.5Cu3Ti4O12 ceramics exhibited high dielectric constants in the order of 104 at room temperature and 1kHz. The loss tangent of the sintered Na0.5Bi0.5Cu3Ti4O12 ceramics was found to be less than 0.2 at room temperature and 1kHz. The impedance spectroscopy analysis revealed that Na0.5Bi0.5Cu3Ti4O12 ceramics were electrically heterogeneous, consisting of insulating grain boundaries and conductive part of the grains. The dielectric relaxation behavior with activation energies of about 0.118–0.127eV observed in the dielectric spectra of the Na0.5Bi0.5Cu3Ti4O12 ceramics was suggested to be the Maxwell–Wagner relaxation type, which was originated from the polarization relaxation at grain boundaries.