Identification of point defects in hydrothermally grown KTiOPO4

Electron paramagnetic resonance has been used to investigate radiation-induced point defects in hydrothermally grown single crystals of potassium titanyl phosphate ( KTiOPO4 or KTP). The crystals were irradiated at 77 K with 60–kV x rays. A trapped-hole center, a Ti3+ center, and a Pt3+ center were observed between 10 and 30 K after the initial 77-K irradiation. These defects become thermally unstable near 160 K. The trapped hole is localized on an oxygen ion adjacent to a potassium vacancy and has resolved hyperfine interactions with three phosphorus nuclei. The Ti3+ ion is the intrinsic self-trapped electron center in KTP and has weak hyperfine interactions with four phosphorus nuclei.