Anjani Kumar

The present work reports the temperature and frequency dependence of a.c. conductivity in glassy Se70Te30−xZnx (x = 0, 2, 4 and 6) alloys in the temperature range 300–500 K and frequency range 1 kHz. An agreement between experimental and theoretical results suggests that the a.c. conductivity behaviour of the present samples can be successfully explained by correlated barrier hopping (CBH) model. The density of defect states has been determined using this model for all the glassy alloys. The results show that bipolaron hopping dominates over single-polaron hopping in this glassy system. This is explained in terms of lower values of the maximum barrier height for single-polaron hopping.

In the present paper, we report the observation of the compensation effect (also known as Meyer–Neldel rule) in thermally activated photoconduction in thin films of Se₇₅In_{25− x} Pb _x . The Meyer–Neldel rule was investigated via two different approaches. In the first, the light intensity was varied while measuring the photoconductivity in amorphous thin films of each sample instead of the changing composition of the glassy system. In the second approach, the composition itself was varied at a particular intensity. The observation of the correlation between pre-factor σ ₀₀ and Meyer–Neldel energy can be described by multiple excitations stimulated by optical phonon energy as described by Yelon and Movaghar [Phys. Rev. Lett. 65 618 (1990)].

The paper reports studies on the glass transition kinetics of Se₇₈Ge₂₂ and Se₆₈Ge₂₂M₁₀ (M = Cd, In, Pb) chalcogenide glasses. Differential scanning calorimetry (DSC) was performed at different heating rates under non-isothermal conditions. Different kinetic parameters, such as glass transition temperature (T _g) and the activation energy of the glass transition (E _t) have been calculated to investigate the effects of Cd, In and Pb additives on the glass transition kinetics of glassy Se₇₈Ge₂₂ alloy.