Structural, optical, dielectric and magneto-dielectric studies on pure and doped PrFeO3

Abstract

Searching for new materials has become important from the view point of both fundamental research and practical applications. Due to their unique properties of multifunctional materials (RFeO3) have been strongly attractive candidates due to their potential applications and interesting physics. PrFeO3 exhibits room temperature (RT) orthorhombic crystal symmetry with Pnma space group and it undergoes through various structural phase transformations under different temperature and pressure conditions. However, it might be possible after, transition metal (TM) ion doped compound may have different potential scopes which have not been explored so far. Both research and industry have been widely studied these type material due to their diverse physical properties and technological applications. The unique properties of perovskite ferrite (PrFeO3) have been strongly attractive candidates due to high dielectric constant and its possible proposed application in spintronic devices and magneto-optical properties. Modern optical spectroscopy is known to probe the electronic structure of various transition metal oxides. Keeping in view the potentials of modern optical spectroscopy, in the present thesis work we aim to investigate the optical property and dielectric properties of prepared oxides as a function of temperature and for different-2 Cr atomic concentrations doped to PrFeO3 to probe the temperature dependent of electronic structure. The purity of structural phase of all prepared polycrystalline PrFeO3 samples has been confirmed through X-ray diffraction (XRD) experiments by refining the XRD data with the help of Fullprof Rietveld refinement package. The band gap for all presently studied samples is determined through diffuse reflectance spectroscopy (DRS) based on the formalism of Kubelka-Munk function and Tauc’s relation. Due to difference in the ionic radius and difference in electronegativity of Cr+3 and Fe+3 it is expected that with Cr doping in PrFeO3 may lead to variation in lattice parameters and consequently variation in band gap. The variation of band gap with temperature iv follows the varshni’s relations that have been confirmed by temperature dependent diffuse reflectance spectroscopy. The variation of Urbach energy (Eu) for all samples for different-2 Cr percentages and as a function of temperature has been studied. There is a significant increase in Urbach energy with increase in temperature and on incorporation of impurities. In addition to this dielectric characterization has been done at room temperature and at low temperature range. The variation of dielectric constant and dielectric loss with Cr doping to PrFeO3 is observed at room temperature, further these variation’s with temperature is also studied in the present work.