Effect of crystal growth on Ti3+ centers in KTiOPO4

Abstract

A series of Ti3+ centers have been formed in hydrothermally grown and flux-grown potassium titanyl phosphate (KTiOPO4 or KTP). These 3d1 defects (S=1/2) were created with 60 kV x rays at 77 K, and electron paramagnetic resonance and electron-nuclear double-resonance (ENDOR) data were taken below 30 K. The ENDOR spectra show that the two Ti3+ centers having the largest concentrations in hydrothermally grown KTP have a neighboring proton, presumably in the form of an adjacent OH− ion. In contrast, ENDOR spectra show that neither of the two Ti3+ centers having the largest concentrations in flux-grown KTP have a neighboring proton. These significant differences in the local environment of the Ti3+ centers may help explain why KTP crystals have shown differing susceptibilities to gray tracking.