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

Electrical properties of new set of glasses with formulation Pb 0.3Ga 0.2In 0.15Zn 0.15Ca 0.2F 2.35(1− x) (PO 3) 2.35 x 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 °C 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=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 σ( ω)= σ(0)+ Bω s . For all formulations, the exponent s is smaller than 1. The evolution of the various electrical parameters as a function of glass composition and temperature are discussed.