Influence of polarization electric field on the dielectric properties of BaTiO3-based ceramics

The titanate of barium (BaTiO3) is a ferroelectric material with perovskite structure. The electric properties (ferroelectricity, positive temperature coefficient, piezoelectricity, etc.) of BaTiO3 were largely studied. Usually, addition of small quantities of impurity can modify the dielectric properties of BaTiO3 and widen its number of applications. In this investigation different additions of sodium niobate (NaNbO3), according to the composition, (1−x) BaTiO3+x NaNbO3 with x=1, 3, 5, 7 and 10 mol%, were considered. Additionally, the effect of simultaneous addition of 3 mol% NaNbO3 and 3 mol% SiO2 on the dielectric properties we studied as function of temperature, frequency and the applied bias. The obtained results reveal a net evolution of permittivity with addition. Furthermore, the obtained results show that the permittivity is independent of the applied electric field at temperature lower than Curie point (Tc), but presents relatively high values at low frequencies. Beyond this temperature, the permittivity considerably increases (about 25×103) and largely depends both on frequency and applied voltage.