Investigation on structural, magnetic, dielectric and impedance spectroscopy properties of ‘Gd’ modified multiferroic-ferroelectric solid solutions

Abstract

A comprehensive study was conducted to analyze the structural, dielectric, impedance spectroscopy and conductivity of Bi0.95Gd0.05FeO3–BaTiO3 (BGF-BT) solid solutions, synthesized via. solid state reaction route. BGF-BT solid solutions show pseudo-cubic structure corroborated by X-ray diffraction patterns and Rietveld analysis. Scanning electron microscopy morphology confirmed that the average grain size decreases with an increase in BT content into BGF. A further insight into the valence chemical states was provided by the core and survey scan of binding energy using the X-ray photoelectron spectroscopy (XPS). The spin-orbit interaction energy in BGF-0.3BT for Fe2p and Bi4f was estimated at 13.3 eV and 5.3 eV respectively. The decrease in oxygen vacancies on incorporation of BT into BGF is also verified after analyzing O 1s core spectra. Raman Spectroscopy also confirmed the chemical bonding and structure of BGF-BT solid solution samples. Maximum magnetization of 1.4047 emu/g was observed for BGF-0.1BT as validated from magnetization hysteresis loops and ferroelectric P vs. E loop measurement confirms the ferroelectric nature of the BGF-BT samples. Analysis of dielectric properties at fixed frequencies confirmed the evidence of magnetoelectric coupling through the broad dielectric anomaly near the reported magnetic transition temperature in BGF-BT samples. The dielectric and impedance spectroscopy studies also confirmed the non-Debye type relaxation phenomenon in the BGF-BT samples. Conductivity measurements followed Jonscher's power law whose experimental fitting determined the pre-factor (A) i.e., polarizability strength and frequency exponent (n). Low activation energy values, 0.187 eV, 0.108 eV and 0.131 eV for BGF-0.1BT, BGF-0.2BT and BGF-0.3BT solid solutions, respectively were observed, show the indication of mobility of defects present in lattice and associated with the hopping conduction mechanism.