Enhancement of dielectric relaxation and AC conductivity of Te(1−x)(GeSe0.5)Scx (0 ≤ x ≤ 0.15) chalcogenide glasses by a rare-earth dopant

Abstract

In the present work, Te_(1−x)(GeSe_0.5)Sc_x were synthesized via a melt-quenching technique and characterized by means of X-ray diffractometry, scanning electron microscopy, and energy-dispersive X-ray spectroscopy for structural, morphological, and elemental analysis, respectively. The dielectric parameters and electrical conductivity were determined to determine the applicability of the synthesized material for use in electronic applications. Temperature and frequency dependence of the dielectric constant, ac conductivity, and dielectric loss of the Te_(1−x)(GeSe_0.5)Sc_x (0 ≤ x ≤ 0.15) (x = 0, 0.05, 0.1, 0.15) chalcogenide alloy were explored in the frequency range of 1 Hz–1 MHz and below the glass transition temperature (T_g) in a temperature range of 302–422 K. It was observed that there was a decrease in both the dielectric loss and constant with an increase in frequency and decrease in temperature. Investigation of the dielectric loss was based on Guintini's model of dielectric dispersion, which is based on the correlated barrier hopping (CBH) model and explained by orientational polarization. A Cole–Cole plot was utilized for determination of some factors, such as distribution parameter, activation energy and molecular relaxation time. The AC conductivity was found to follow the power law (Aω^s) and the frequency exponent s ≤ 1 was noted to reduce with an increase in temperature, which concluded that the CBH model is appropriate for defining the AC conductivity of the prepared samples. The incorporation of Sc tended to increase the localized states density in the tails and, accordingly, there was an increase in the ac conductivity. Hence, the studied material is a promising candidate for phase-change memory applications.