Synchrotron radiation topographic observation of KTiOPO4 crystals under an electric field

In situ white-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 for hkl reflections (l not equal 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.