High dielectric permittivity of Li and Ta codoped NiO ceramics

Phase evolution, microstructure and dielectric behaviour of Li and Ta codoped NiO (LTNO) ceramics were studied. The content of Ta2O5 was mainly dispersed into the grain boundaries and exists as the NiTa2O6 phase. The concentration of Ta has a remarkable effect on the dielectric properties of the LTNO ceramics. The sample with Ta = 5% has the highest dielectric constant of the three LTNO samples. The activation energy for the LTNO (Ta = 5%) sample was 0.126 eV and relaxation time was 3.51 x 10(-10) s. These correspond to the dielectric relaxation processes. The high dielectric constant response of the LTNO ceramics is due to the formation of a barrier layer between the grain boundaries. Orientational and space charge polarization contribute to the dielectric behaviour observed.