Optical Birefringence Investigation of the Memory Effect in Barium Sodium Niobate

Abstract

We analyze optical birefringence measurements subsequent to annealings at various temperatures in the incommensurate phase of Ba 2 NaNb 5 O 15 . We observe a complex behaviour assigned to the fact that a coexistence of the incommensurate phase with the “quasicommensurate” phase can be induced by the annealings. Results concerning the role of stoechiometry defects are also discussed.