Dielectric relaxation in glassy $Se_{100-x}$ $Sb_x$

Özet

Frequency and temperature dependence of dielectric constant $\varepsilon^\prime$ and dielectric loss $\varepsilon^{\prime \prime}$ 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, 0.66, 0.08 and 0.10) dielectric dispersion starts in the upper frequency and temperature range. The values of $\varepsilon^\prime$ and $\varepsilon^{\prime \prime}$ ,as functions of temperature and frequency, increase with Sb concentration to x = 0.08; at which point a discontinuity is observed. Above 8%, $\varepsilon^\prime$ and $\varepsilon^{\prime \prime}$ 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.