Synchrotron radiation topographic observation of KTiOPO4crystals under an electric field

Abstract

In situwhite-beam synchrotron radiation topographic observations under an electric field have been made on the KTiOPO4(KTP) family of crystals. The investigation shows a strong enhancement of diffracted intensity forhklreflections (l ≠ 0) and topographic contrast in the form of fine striations when the external electric field is parallel to the polar axis. Several kinds of doped and undoped samples with various grown-in defects, such as domain boundaries, growth striations, growth-sector boundaries, dislocations,etc., have been studied in detail. The results suggest that these defects have very little effect on the field-induced striations. It is believed that the movement of K^+ ions driven by the electric field leads to a local accumulation of charges and a lattice distortion. The strongly anisotropic conductivity is a governing factor in the explanation of the field-related phenomena in this kind of quasi-one-dimensional conductor.