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

KTiOPO 4 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 КРО 3 and potassium orthophosphate К3РО 4 by using a Czochralski modified method. Potassium–sodium titanyl phosphate crystals were obtained from KTiOPO 4 crystals by the potassium isomorphic replacement with sodium; to this purpose, sodium chemical diffusion from NaNO 3 melt was used. Their ionic conductivity was studied by the electrochemical impedance spectroscopy method. The KTiOPO 4 crystal doping with rubidium and sodium ions was shown to lower the conductivity, whereas the doping with fluorine ions results in increased conductivity.