Complex dielectric and impedance behavior of magnetoelectric Fe2TiO5

TL;DR

This study explores the dielectric and impedance properties of Fe2TiO5, revealing grain and grain boundary contributions, thermally activated relaxation, and conduction mechanisms relevant for magnetoelectric applications.

Contribution

It provides a detailed analysis of the temperature and frequency-dependent dielectric behavior and conduction mechanisms of Fe2TiO5, highlighting the roles of grain and grain boundary effects.

Findings

Dielectric permittivity sharply increases above 200K.

Grain boundary contributions appear above 175K at low frequencies.

Conduction follows the correlated barrier hopping model.

Abstract

We have investigated the complex dielectric and impedance properties of magnetoelectric compound Fe2TiO5 (FTO) as a function of temperature (T) and frequency (f) to understand the grain (G) and grain boundary (Gb) contributions to its dielectric response. The temperature and frequency dependent dielectric permittivity data shows a sharp increase in permittivity above 200K accompanied with a frequency dependent peak in loss. At T less than 175K, only G contribution dominates even at lower frequency (nearly 100Hz), but for T greater than 175K, the Gb contribution starts appearing at low frequency. The value of critical frequency distinguishing these two contributions increases with increasing temperature. The observed non-Debye dielectric relaxation follows thermally activated process and is attributed to polaron hopping. Further the frequency dependence of ac conductivity follows the Jonscher power-law. The temperature dependency of critical exponent s shows that the correlated barrier hopping model is appropriate to define the conductivity mechanism of FTO in the studied temperature regime.