Temperature dependent dielectric properties and ac conductivity of GdFe1−xMnxO3 (0 ≤ x ≤ 0.3) perovskites

Abstract

We have synthesized the nano-crystalline samples of GdFe1−xMnxO3(0 ≤ x ≤ 0.3) via solid state reaction route and studied their dielectric properties and ac conductivity in detail. X-ray diffraction patterns show monophase structure of the samples in orthorhombic crystal symmetry (space group Pbnm). The enhancement in dielectric constant is registered on Mn doping at room temperature as well as with the rise in temperature at a constant frequency. The fitting of Cole–Cole plots indicate the non-Debye kind relaxation mechanisms in the samples. The real (Z′) and imaginary (Z″) components of impedance reduce with the increase in frequency and Mn ions in GdFeO3 lattice. Nyquist plots are fitted to a single semicircle that hints towards the single relaxation process. The ac conductivity (σac) is also increased with the frequency and follow the power law,σac(ω) = Aωs wherein the exponent ‘s’ reduces with frequency. We have estimated the activation energies with the help of ln(σ) versus 1/T plots that remain almost constant below 350 K and show variation with the Mn doping in GdFeO3 perovskite at temperatures 620–673 K. The polaron hopping energy (WM) in the framework of the correlated barrier hopping (CBH) and non-overlapping small polaron tunneling (NSPT) models have been calculated and its variation with temperature signifies thermally activated conduction mechanism in the studied materials.