Domain structures induced by defects in Ba2NaNb5O15and LiNbO3

Abstract Systematic observations of ferroelectric and ferroelastic domains induced by defects, such as dislocations, inclusions and twins, are reported for as-grown barium sodium niobate and lithium niobate crystals. The main characteristics of defect-induced domains in these crystals are described. It is found that shapes of ferroelectric domains induced by dislocations depend upon directions of dislocation lines and domain structures of matrix in both crystals, and are related with the Burgers vectors in LiNbO3 but are independent of them in Ba2NaNb5O15.