Electric modulus spectroscopy of lithium tetraborate (Li2B4O7) single crystal

The lithium tetraborate (Li2B4O7; LBO) crystals were successfully grown by Czochralski technique. The frequency and temperature dependences of dielectric constant and ac conductivity were investigated in the frequency from 100 Hz to 10 MHz along c-axis. The dielectric anomaly with broad peak about 300 degreesC was observed in the temperature from 200 degreesC to 500 degreesC. The ac conductivity is frequency independent at high temperature and low frequencies, and shows a frequency dispersion at low temperature. The relaxation in ionically conducting LBO crystal analysed in terms of modulus formalism. The electric modulus which describes the dielectric relaxation behavior is fitted to the Kohlrausch-Williams-Watts (KWW) exponential function. The activation energy with 0.34 eV was estimated by Arrhenius plot of relaxation frequency, which is related to ionic hopping conduction. The temperature dependence of the electric relaxation of modulus was studied and the results were discussed.