Electrical conductivity of potassium titanyl phosphate KTiOPO4 pure crystals and those doped with Na+, Rb+, and F– ions

Abstract

KTiOPO4 crystals, both pure and doped with rubidium Rb+ and fluorine F– ions, were grown in temperature range from 1060 to 846°С from salt solvent containing potassium metaphosphate КРО3 and potassium orthophosphate К3РО4 by using a Czochralski modified method. Potassium–sodium titanyl phosphate crystals were obtained from KTiOPO4 crystals by the potassium isomorphic replacement with sodium; to this purpose, sodium chemical diffusion from NaNO3 melt was used. Their ionic conductivity was studied by the electrochemical impedance spectroscopy method. The KTiOPO4 crystal doping with rubidium and sodium ions was shown to lower the conductivity, whereas the doping with fluorine ions results in increased conductivity.