IONIC-CONDUCTION ASSOCIATED WITH POLARONIC HOPPING IN KTIOPO4 SINGLE-CRYSTAL

The frequency dependent a.c. conductivity in KTiOPO4 single crystal, in the range from 10 Hz to 100 kHz, has been measured as a function of temperature between 200-degrees-C and 700-degrees-C. The behavior of sigma(ac) in the low frequency range well obeys the universal power law, sigma(ac) = sigma(dc) + Aomega(S). The temperature dependence of exponent s is described by the OLP model. It is evidently shown that ionic transport behavior in KTP may well be explained by the contribution of polaronic hopping between localized sites.