Structural and dielectric properties of GdFeAsO ceramic material

Abstract

The iron-based ceramic GdFeAsO has been prepared by the solid-state reaction method. To identify the ceramic and its multiple applications we have performed structural, micro structural and electrical characterizations of the sample. The crystalline size and structure are calculated at room temperature using the X-ray Diffraction (XRD) technique. Tetragonal structure has been ensured from XRD. The lattice strain of the crystal is obtained using W.H. Plot, which ensured the structural stability of the crystal. The field emission scanning electron microscopy (FESEM) technique is used to study the surface morphology of the sample. Polycrystalline grains having spherical and cylindrical sizes of ranges 1-3 micrometer are obtained. The observed prominent peaks at 107.1cm−1,150.4cm−1,216.6cm−1,296.6cm−1,344.6cm−1 and 440.37cm−1 in the Raman spectra of the sample, are for the cubic phase of the Gd2O3 in the GdFeAsO compound material. The peak at 623.0cm−1 corresponds to α-Fe2O3 in the spectra reveals the presence of impurity oxide phases. The broad peaks in the Differential Scanning Calorimetry (DSC) graph at about (290°C) and (600°C) reveals the initiation of slow crystallization of the sample within the given temperature range. The dielectric properties such as the dielectric constant (εr) and loss tangent (tanδ) of the sample have been studied at different temperatures and frequencies with LCR meter. The high value of dielectric constants is seen to exist in the materials. There are two dielectric anomalies that are observed at lower and higher temperature region. The magnetic measurement has been performed by using Vibrating Sample Magnetometer (VSM) at room temperature and showed the non linearity in the magnetization versus field curve.