Electrical conduction and dielectric properties of lithium aluminum silicate glasses doped with Cr3+ ions

Abstract

Amorphous lithium aluminum silicate glass system (LAS) implanted with chromium ions are prepared. The ac and dc conductivities (σac and σdc) of as-prepared bulk samples are measured under vacuum in the temperature range 373-153 K and displayed dielectric dispersion in the frequency range 50 Hz-80 kHz. The ac conductivity versus frequency plots were analyzed by considering a power law: σac ∝ ωs (s ≤ 1). A comparison between values of the index s with those numerically calculated from different conduction models reveals that correlated barrier hopping (CBH) is a fairly good model to describe the dominant ac conduction mechanism. The concept of the Meyer-Neldel (MN) rule in the expression of the relaxation time is considered for both ac and dc experimental data. The validity of the CBH model based on the MN (normal and inverted) rule is studied and discussed. Besides, results of the real dielectric constant (ε′), loss factor (ε″) and loss tangent (tan δ) together with the Cole-Cole diagrams and the optical (ε∞) and static (εs) dielectric constants for the studied samples are given and discussed. Crown Copyright © 2009.