Antiferromagnetic behaviour and dielectric relaxation of xBa2FeNbO6-(1-x)LaFeO3 [x = 0.1, 0.3, 0.5]

In this work we have investigated the magnetic and dielectric properties of xBa2FeNbO6-(1-x)LaFeO3 [x = 0.1, 0.3, 0.5] prepared by the solid state reaction technique. The Rietveld refinement of the X-ray diffraction pattern of the samples is performed to confirm the phase formation as well as the crystal structure of the materials. The x = 0.1 and 0.5 materials have orthorhombic Pbnm and cubic Fm3m crystal symmetry respectively. Whereas x = 0.3 material has both Pbnm (83.64%) and Fm3m (16.36%) phases. The effect of lattice distortion on the magnetic and dielectric properties has been discussed. The temperature dependent magnetization study reveals the anti-ferromagnetic behaviour of the materials. The magnetic field dependence magnetization curve indicates the canting of Fe3+ spins in these materials like LaFeO3. The value of magnetization has increased with respect to pure LaFeO3. The dielectric relaxation of the materials is analyzed within impedance and electric modulus mechanisms. The value of conductivity and dielectric constant increases with the increase of x value. Two semi-circular arcs in the complex impedance plane plot originate due to the grain and grain-boundary contributions which give rise to two dispersion regions in the frequency dependence conductivity spectra of the materials. The complex impedance plane plot is described by an electrical equivalent circuit consisting of two parallel RC elements connected in series.