Modulus spectroscopy of potassium lithium niobate (K3Li2Nb5O15) single crystal

The modulus spectroscopy of potassium lithium niobate (KLN) crystals was in vestigated in the frequency range from 100 Hz to 10 MHz and temperature ran ge from 30 degreesC to 600 degreesC. The dielectric anomaly with a broad pe ak was observed around 430 degreesC. The ac conductivity is frequency depen dent at low temperatures such as sigma = sigma (dc) + A omega (s), and show s a frequency independent at low frequencies and high temperatures. The ele ctrical relaxation in ionically conducting KLN crystal analysed in terms of modulus formalism. The electric modulus which describes the dielectric rel axation behavior is fitted to the Kohlrausch-Williams-Watts (KWW) exponenti al function. Near the phase transition temperature, a stretched exponential parameter beta indicating the degree of distribution of the relaxation tim e has a small value. The activation energy near the phase transition temper ature is different from that of above and below phase transition temperatur e. The temperature dependence of the electric modulus is studied and the re sults are discussed.