Effects of sintering atmosphere (N2 and O2) on dielectric properties and electrical conductivity of Na(Nb1-xTax)O3 ceramics

Na(Nb1-xTax)O-3 (NNT, x = 0, 0.05, and 0.10) ceramics were prepared by conventional solid-state reaction method in the oxygen (O-2) and nitrogen (N-2) sintering atmospheres, respectively. The phase structure, surface microstructure, dielectric constant (epsilon), dielectric loss (tan delta), and frequency dispersion of AC conductivity (sigma(ac)) of the NNT ceramics have been investigated. The results show that the NNT ceramics are of antiferroelectric orthorhombic phase. The values of epsilon of the NNT ceramics sintered in N-2 are larger than those sintered in O-2 at all temperatures, and the Curie temperature (T-C) of the NNT ceramics sintered in N-2 or O-2 decreases from about 370 degrees C to 330 degrees C as x increases from 0 to 0.10. The electrical conductivity analysis shows that the quasi-static activation energies (E-a) at 1 Hz of the samples sintered in O-2 are larger than in N-2, especially for x = 0. These results are expected to promote the research and applications of the NNT-based systems.