Dielectric Properties of NaNbO3 Ceramics

Abstract

Five phase transitions were observed in NaNbO3 ceramics on cooling by broadband (20 Hz-1 GHz) dielectric investigations in temperature range from 25 K to 1000 K. Despite that T1-T2 and S-T1 phase transitions are non polar, they are clearly expressed in dielectric properties of ceramics due the corresponding conductivity anomalies. At higher temperature (above 600 K) the electrical conductivity dominates in the dielectric spectra of ceramics. The electrical conductivity increases after annealing and have peculiarities close to T1-T2, S-T1, P-R phase transitions temperatures. Two dielectric dispersion processes, at low temperatures (in N phase below 120 K) with very low activation energy and freezing temperatures values, are assigned to domains dynamics.