Dielectric Relaxation in Glassy Se_{100 - x} Sb_x


Abstract: Frequency and temperature dependence of dielectric constant \varepsilon' and dielectric loss \varepsilon'' are studied in glassy Se_{1-x} Sb_x (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.10) in the frequency range from 1--10 kHz and in the temperature range 290 K to 360 K. The experimental results indicate that no dielectric dispersion exist in glassy Se in the operating range of frequencies. However, when Sb concentration increases in Se_{1-x} Sb_x (x = 0.02, 0.04, 0.06, 0.08 and 0.10) dielectric dispersion starts in the upper frequency and temperature range. The values of \varepsilon' and \varepsilon'', as functions of temperature and frequency, increase with Sb concentration to x = 0.08; at which point a discontinuity is observed. Above 8\%, \varepsilon' and \varepsilon'' decrease with Sb concentration. The discontinuity is explained in terms of the mechanically stabilized structure at a particular average co-ordination number. An analysis of the observed dielectric loss shows that the Guintini's theory of dielectric dispersion based on two electron hopping over a potential barrier is applicable in the present case.

Keywords: Chalcogenide glasses, Dielectric relaxation.

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