Conductivity relaxation in zirconium fluoride glasses: effect of substitution of Zr by Y ions

The electrical conductivity and the conductivity relaxation of (55?x)ZrF₄–15BaF₂–xYF₃–30LiF glasses were studied in the temperature range from 300 K to just below the glass transition temperature and in the frequency range from 10 Hz to 2 MHz. No large changes in the conductivity were observed with the substitution of Zr⁴⁺ by the Y³⁺ ions. The activation energy remained almost constant up to 20 mol.% YF₃ content and increased for higher YF₃ content in the glass compositions. The frequency dependent conductivity was analyzed in terms of modulus formalism. The distribution parameter for the conductivity relaxation times remained almost unchanged with the substitution of YF₃ with an increase for 40 mol.% YF₃ content. The distribution of relaxation times of the present glasses was much broader than that for the YF₃-free zirconium fluoride glasses. The glass decoupling index decreased and the modulus relaxation rate increased with the increase of YF₃ content in the glass compositions with an anomaly for the composition having 20 mol.% YF₃ content.