Influence of Y and Co co-doping in the multiferroic behaviors of BiFeO₃ ceramics

Abstract

Single phase of pure BiFeO$_{3}$ (BFO) and ${{{{\text{Bi}}_{0.99}{\text{Y}}_{0.01}{\text{Fe}}}_{1-{x}}\text{Co}_{{x}}\text{O}_{3}}}$ ($0.01\le x\le 0.03$) ($\text {BYFC}$) multiferroic ceramics were prepared by using a modified solid state reaction method. The scanning electron microscope (SEM) images revealed that the grain size and morphology were dependent on the nature of dopant. X-ray diffraction peaks were found to belong to the pure $\text {BFO}$ structure with R3c space group of symmetry. It was found that the dielectric constant ($\varepsilon '$) values increased $\sim$13.5 times with the addition of Co ions; being $\sim$170 and $\sim$2300, for pure BFO and $x=0.01$, respectively, at the lower frequencies (100 Hz). The dielectric behavior was described by the modified Cole–Cole model. Ferromagnetic (FM) ordering with saturation magnetization, $M_{s}$, and coercivity $H_{c}$ values of $\sim$0.75 emu/g and $\sim$ $\text {400 Oe}$, was found in the BYFC ceramics at $\text {x = 0.03}$ at room temperature. A decrease in the band gap was observed due to the amount of doping in the BYFC ceramics. The origin of the enhanced dielectric and magnetic properties was discussed on the basis of the size effect and the nature of the dopants like $\text {Y}^{3+}$, ${{{\text{Co}}^{2+}}}$ and ${{\text{Co}}^{3+}}$ ions in the lattice structure of the doped ceramics.