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
Publication Date (Web): May 16, 2018
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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 Mr and magnetization are varied irregularly upto Ca (4 at. %). But for x = 0.01 Mr and magnetization are highest. The values of magnetization and Mr 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.
Sol-Gel method, Ca doped BiFeO3: Ba, band gap studies, magnetic properties, dielectric properties.