Dielectric Properties and Phase Transitions of NaNbO3and (Na,K)NbO3

Abstract

An optical, dielectric, and structural study has been carried out on NaNb${\mathrm{O}}_3$ and the solid solution (Na,K)Nb${\mathrm{O}}_3$, both single crystals and ceramics being used. No evidence for ferroelectricity in NaNb${\mathrm{O}}_3$ was found, and the crystal seems to be antiferroelectric in accordance with the nonpolar structure reported by Vousden. It is shown that a small addition of KNb${\mathrm{O}}_3$ to pure NaNb${\mathrm{O}}_3$ produces a new ferroelectric phase, the existence of which suggests a possible explanation of the conflicting dielectric and structural properties previously reported.