Relaxation dynamics of charge carriers in mixed alkali fluoride glasses

Abstract

We have reported the relaxation dynamics of charge carriers in mixed alkali fluoride glasses of compositions 50ZrF₄-10BaF₂-2YF₃-3AlF₃-(35-x)LiF-xNaF; where 0 x 35. We have analyzed the relaxation data for these mixed alkali glasses, taken in the frequency range from 10 Hz to 2 MHz and in the temperature range from room temperature to just below the glass transition temperature, in the framework of the electric modulus formalism. We have observed the mixed alkali effect in the conductivity and the conductivity relaxation for these mixed alkali fluoride glasses, where anions also participate in the diffusion processes in addition to cations unlike mixed alkali oxide glasses. We have also observed mixed alkali effect in decoupling index. The scaling property of the modulus spectra of these mixed alkali glasses shows that the relaxation in fluoride glasses is independent of the temperature, but is dependent on composition.