Electric conductivity and relaxation in fluoride, fluorophosphate and phosphate glasses: analysis by impedance spectroscopy

Electrical properties of new set of glasses with formulation Pb0.3Ga0.2In0.15Zn0.15Ca0.2F2.35(1-x)(PO3)(2.35x) with x equal to 0, 0.1, 0.25, 0.75, 0.90 and 1.0 were investigated. Electrical measurements were carried out by impedance spectroscopy in the frequency range from 5 Hz to 13 MHz. All measurements were performed from 100 up to 30 degreesC below of the glass transition temperature (T-g) of each composition. The ac conductivity increases with temperature increasing following the Arrhenius law, with a single apparent activation energy for conduction process. The lowest activation energy value of 0.77 eV was derived for fluoride glass (x approximate to 0). E-a value reaches to 1.21 eV for fluorophosphate glass (x = 0.75) The frequency dependence of the electric conductivity follows a simple power law behavior, in according to relation sigma(omega) = sigma(0) + Bomega(S). For all formulations, the exponent s is smaller than I The evolution of the various electrical parameters as a function of glass composition and temperature are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.