Complex dielectric and impedance behavior of magnetoelectric Fe2TiO5

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 (G(b)) contributions to its dielectric response. The temperature and frequency dependent dielectric permittivity (epsilon') data shows a sharp increase in permittivity above 200 K accompanied with a frequency dependent peak in tan delta. At T < 175 K, only G contribution dominates even at lower frequency (similar to 100 Hz), but for T >= 175 K, the G(b) 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's power-law. The temperature dependency of critical exponent 's' shows that the correlated barrier hopping model is appropriate to explain the conductivity mechanism of FTO in the studied temperature regime. (C) 2015 Elsevier B.V. All rights reserved.