Electrical transport studies in barium borovanadate glasses

ISSN： 0031-9090

Source： Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B, Vol.43, Iss.1, 2002-02, pp. : 1-6

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Abstract

The electrical response of four barium borovanadate glasses, 15V₂O₅.xBaO.(85-x)B₂O₃, where x = 20, 25, 30 and 35 mol%, has been investigated between room temperature and 600 K as a function of frequency (0·1-500 kHz). DC activation barriers calculated from the complex impedance plots decrease linearly with BaO concentration indicating that ionic conductivity dominates in these glasses. The possible origin of low temperature departures of conductivity curves (from linearity) of vanadium rich glasses in ln σ versus 1/T plots is discussed. The ac conductivity curves have been fitted to the Almond-West type power low expression σ (ω) = σ (0) + Aω^s with use of a single value of s. It is found that most of the glasses exhibit a temperature dependent minimum. The dielectric data are converted into moduli (M*) and are analysed using the Kohlrausch-Williams-Watts (KWW) stretched exponential function. The activation barriers, w, calculated from the temperature dependent dielectric loss peaks compare well with the activation barriers, ΔE, calculated from the dc conductivity plots. The stretching exponent β is found to be temperature independent and is not likely to be related as in the equation β = 1-s.