Electrical transport properties of 0.5Li2O–0.5M2O–2B2O3 (M = Li, Na and K) glasses

Transparent glasses in the system 0.5Li2O–0.5M2O–2B2O3 (M = Li, Na and K) were fabricated via the conventional melt quenching technique. The amorphous and glassy nature of the samples was confirmed via the X-ray powder diffraction and the differential scanning calorimetry, respectively. The frequency and temperature dependent characteristics of the dielectric relaxation and the electrical conductivity were investigated in the 100 Hz–10 MHz frequency range. The imaginary part of the electric modulus spectra was modeled using an approximate solution of Kohrausch–Williams–Watts relation. The stretching exponent, β, was found to be temperature independent for 0.5Li2O–0.5Na2O–2B2O3 (LNBO) glasses. The activation energy associated with DC conduction was found to be higher (1.25 eV) for 0.5Li2O–0.5K2O–2B2O3 (LKBO) glasses than that of the other glass systems under study. This is attributed to the mixed cation effect.