A HIGH-PRESSURE STRUCTURAL STUDY OF POTASSIUM TITANYL PHOSPHATE (KTP) UP TO 5 GPA

The crystal structure of KTiOPO4 (KTP) has been determined as a function of pressure up to 5 GPa at room temperature, using x-ray diffraction techniques and a single-crystal sample. The principal changes with pressure are in the coordination environments of the potassium atoms and in the linking angles of the TiO6-PO4 structural framework. In general the distortions of the TiO6 octahedra, which have been linked to the second harmonic generating properties of KTP, are retained although there are some small changes in the Ti-O bond lengths. The overall structural changes are consistent with a first-order character for the phase transition at 5.5 GPa.