Growth and domain structure of potassium titanyl phosphate crystals pulled from high-temperature solutions

Potassium titanyl phosphate (KTP) single cyrstals have been by the top-seeded solution growth (TSSG) method with pulling from the K₆P₄O₁₃ flux above the Curie temperature. Use of [100]-oriented seeds has been found to yield single pyramid growth with a planar solid-liquid interface. Over 90% of the interface is usually formed by the (100) facet. Optical and microscopic characterization has demonstrated a complete abscence of inclusions in all cyrstals grown. The piezoelectric measurements method has been employed for two- and three-dimensional mapping of the domain structure of as-grown crystals. A bulk bi-domain structure (with the domain boundary closely parallel to the (001) plane) surrounded by a 0.5-2.0 mm thick layer of surface domains has been revealed. A high-temperature treatment technique, in air and in an atmosphere of KTP fine crystalline powder, has been developed for poling of KTP crystals without application of an external electric field. The time-dependence of the inverted domain layer thickness has been studied and found to exhibit a diffusional character. Preliminary experiments indicate that the domain inversion may be mainly associated with the in- and outdiffusion of the potassium atoms.