A Synchrotron X-ray Study of Ferroelectric Switching, Domain Reversal and Piezoelectric Moduli in CsTiOAsO₄, Under an Applied Electric Field

Single crystals of caesium titanyl arsenate (CTA, CsTiOAsO₄), with space group Pna2₁ and isomorphous with potassium titanyl phosphate (KTP, KTiOPO₄), have been studied using high-resolution synchrotron X-rays. During the experiments, an electric field was applied along the polar axis [001]. Single-crystal plates, between 300 and 450 μm thick along [001], were polarized by a variable square wave of frequency 20 Hz alternately applied to each side of the plate. A field-induced splitting of the + /− peaks for reflections hkl with l ≠ 0 was observed. This splitting provides information about the coercive field, polarizability and the piezoelectric strain tensor. Two of the piezoelectric coefficients of CTA could be estimated as d₃₁ ≃ 1 and d₃₃ ≃ 27 pm V⁻¹. Whereas the coercive fields were estimated at 2300 V mm⁻¹, the field necessary to reverse the domains just once in CTA was found to be either 560 or 1550 V mm⁻¹, depending on the polarity of the reversed domain in relation to the polarity of the nonswitched part of the crystal.