Dielectric Properties and Phase Transitions of NaNb O 3 and (Na,K)Nb O 3

摘要: An optical, dielectric, and structural study has been carried out on NaNb${\mathrm{O}}_{3}$ the solid solution (Na,K)Nb${\mathrm{O}}_{3}$, both single crystals ceramics being used. No evidence for ferroelectricity in was found, crystal seems to be antiferroelectric accordance with nonpolar structure reported by Vousden. It is shown that a small addition of KNb${\mathrm{O}}_{3}$ pure produces new ferroelectric phase, existence which suggests possible explanation conflicting dielectric properties previously reported.The phase diagram NaNb${\mathrm{O}}_{3}$-KNb${\mathrm{O}}_{3}$ given. This, together optical x-ray studies NaNb${\mathrm{O}}_{3}$, shows three transitions are quite different nature from BaTi${\mathrm{O}}_{3}$-type KNb${\mathrm{O}}_{3}$.