Domain reversal and wall structure of 180° ferroelectric domains in LiTaO[sub 3] crystals

Abstract

We report a dramatic influence of lithium nonstoichiometry in LiTaO3 crystals on the 180° coercive fields, internal fields, domain wall strain, optical birefringence, and domain shape. Congruent composition of LiTaO3([Li]/([Li]+[Ta])∼0.485) show large coercive fields of ∼21 kV/mm for domain motion and built-in internal fields of ∼4.5 kV/mm, domain wall strains of |εzz|∼(1–10)×10−6, optical birefringence in the z-plane, and triangular domains with domain walls parallel to the crystallographic x-axes. On the other hand, near-stoichiometric crystals of LiTaO3([Li]/([Li]+[Ta])∼0.499) studied here show low coercive fields of ∼1.7 kV/mm, internal fields of <0.1 kV/mm, negligible domain wall strain or optical birefringence, and six-sided domains with domain walls parallel to crystallographic y-axes.