Investigation of the crystal chemical and ferroelectric properties in the vicinity of LiNbO 3 and LiTaO 3 inside the ternary systems Li 2ONb 2O 5(TiO 2) 2 and Li 2OTa 2O 5(SnO 2) 2

Abstract

A crystal chemical study has been carried out for the ternary systems Li 2O M 2O 5( M′O 2) 2 ( M = Nb, M′ = Ti; M = Ta, M′ = Sn), in order to characterize and delimit the extension of domains of solid solutions in the vicinity of LiNbO 3 and LiTaO 3. The nature of the nonstoichiometry within these regions of solid solution has been found to be of a cationic excess or deficit. No evidence for anionic deficit has been found in this study. The ferroelectric Curie temperature T C decreases as the composition deviates from LiNbO 3 or LiTaO 3. The decline in T C has been interpreted on the basis of the electrostatic interactions resulting from either cationic excess or deficit.