Dielectric behaviour and AC conductivity of sodium borate glass containing CoO

Sodium borate glasses of composition (Na2B4O7)(100-x)(CoO)(x), with x = 0, 3, 5 and 7 mol%, were prepared by melting oxide mixtures in a platinum crucible at 1050 degrees C in an electric furnace in air for 2 h, and then quenching in air. The IR spectra, AC conductivity and dielectric behaviour of the quenched glasses are the subject of the present work. Properties such as dielectric constant, loss factor tangent and electrical conductivity as a function of frequency and temperature are reported. The AC conductivity is proportional to omega(s) and increased as cobalt content was decreased. The value of the exponent (5) decreased with decreasing CoO content. From the IR spectra, it was found that increasing CoO does not seem to introduce any new absorption band. Also, the activation energies for AC conductivity and the activation energies associated with the relaxation process for different glass samples are calculated. (C) 1998 Elsevier Science Ltd. All rights reserved.