Magnetic and dielectric properties of divalent Ca2+ and Ba2+ ions co-doped BiFeO3 nanoparticles

Department of Physics, Sri Venkateswara University, Tirupati 517 502, India

Adv. Mater. Lett., 2018, 9 (3), pp 175-181

DOI: 10.5185/amlett.2018.1411

Publication Date (Web): May 16, 2018

Copyright © IAAM-VBRI Press

E-mail: vijayaraguru@gmail.com

Abstract

Pristine BiFeO₃ (BFO) and Ca doped BiFeO₃: Ba nanoparticles (NPs) were synthesized in aqueous solution by sol-gel method with Tartaric Acid as a chelating agent. EDAX measurements confirmed the presence of Ca, Ba in the BiFeO₃ host lattice. X-ray diffraction analysis showed that the average grain size of the prepared samples was in the range of 09–28 nm. The lattice structure of the nanoparticles transformed from rhombohedral to tetragonal phase with Ca²⁺ ions substitution increased. TEM images indicated that sphere and square shape of nanoparticles through a size ranging from 10 to 15 nm. Diffusion reflectance spectra of BiFeO₃ NPs showed a substantial blue shift of ~100 nm (630 nm -> 530 nm) on Ca, Ba co-doping which corresponds to increase in band gap by 0.47 eV. Dielectric constant (ε’) and dielectric loss (ε’’) were measured in the frequency range 1 Hz to 1 MHz at room temperature. Dielectric constant and loss are increased with Ca concentration except for Ca (4 at. %). The bulk conductivity (σ) increases from 3.07 x 10^-6 S/m to 1.64 x 10^-5 S/m as the Ca concentration increased from 0.00 to 0.03. Magnetic measurements revealed the ferromagnetic character of Pristine BFO and Ca doped BiFeO₃: Ba samples. It is observed that by increasing the Ca concentration the value of M_r and magnetization are varied irregularly upto Ca (4 at. %). But for x = 0.01 M_r and magnetization are highest. The values of magnetization and M_r for 1% Ca doped BiFeO₃: Ba NPs are 2.99 emu/g, 1.54 emu/g, respectively, which are quite significant at room temperature. These materials have potential applications in data storage, switching devices, spintronics, sensors and microelectronic. 

Keywords

Sol-Gel method, Ca doped BiFeO₃: Ba, band gap studies, magnetic properties, dielectric properties.