Dielectric relaxation in flux grown KTiOPO4 and isomorphic crystals

Dielectric spectroscopy and de conductivity have been studied in KTiOPO4 an d isomorphic crystals in a temperature range 150-400 K. The experimental da ta indicate two temperature regions related to different types of relaxatio n processes. Alternation of the activation energy, suppression of the diele ctric dispersion, and decreasing dissipation factor by three orders of magn itude has shown that the superionic state in KTiOPO4 and its isomorphs tran sit gradually to the dielectric state with temperature lowering. The transi tion leads to variation of transport properties from ionic to electronic co nductivity. It was found that the parameters of the relaxation process (act ivation energy in the superionic state, temperature range of transition fro m ionic to electron conductivity) are determined by the sort of mobile cati ons. The temperature dependence of conductivity relaxation time was obtaine d from the electric modulus plots. (C) 2001 American Institute of Physics.