Enhancement of structural, magnetic, dielectric, and transport properties of Nb substituted 0.7BiFeO3-0.3BaTiO3 solid solution

The present study reports the structural, magnetic, dielectric, transport, and electronic properties of Nb substitution in the multiferroic (0.7-x)BiFeO3-0.3BaTiO(3)-xNb(2)O(5) solid solution. Rietveld refined x-ray diffraction results confirm the perovskite phase formation along with a transformation in the structural symmetry, which exhibit a monotonous enhancement in the unit cell parameter with Nb substitution and a monotonous increase in the lattice parameters is observed with increased Nb concentration. Subsequently, scanning electron micrographs and Raman spectroscopy substantiates these structural changes. Interestingly, magnetic ordering temperature and net magnetization enhanced remarkably for the Nb substituted samples and a maximum value of saturation magnetization (1.95 emu/g) is accomplished for x = 0.10, which is significantly higher as compared with 0.11 emu/g for the parent compound (x = 0). A large value of remanence magnetization (0.8 emu/g) for the highest Nb-dopant (x = 0.10) is obtained as compared to other transition metal-doped BF-BT systems, which make it very useful in memory device applications. Two dielectric anomalies within the temperature ranges of 200 <= T <= 400 degrees C and 400 <= T <= 500 degrees C appear due to Nb substitution in the BF-BT phase. The phenomenon of dielectric relaxation with a larger dielectric constant was observed near the Curie temperature. Temperature-dependent dielectric and magnetic study confirm the coupling between electric and magnetic dipoles in all Nb substituted samples. Impedance spectroscopy results within the frequency (100 Hz <= upsilon <= 1 MHz) confirm Debye-type behavior and maximum bulk resistance of similar to 110 k Omega for x = 0.10. Conductivity data follow Jonscher's power law and confirms that the conduction phenomenon is dominated by the mechanism of charge carriers hopping. Arrhenius model estimate the values of activation energies for x = 0, 0.03, 0.05, and 0.10 samples to be 0.61, 1.12, 1.08, and 1.22 eV, respectively. Room temperature x-ray photoemission spectroscopy measurements for the constituent Bi, Ba, Ti, and Nb elements exhibit that they exist in their 3+, 2+, 4+, and 5+ valence states, respectively, which do not alter with the increased Nb substitution. The core-level spectra of Fe 2p manifest a complex multiplet structure and confirms its trivalent state in the samples. (C) 2021 Elsevier B.V. All rights reserved.