Articles written in Bulletin of Materials Science
Volume 34 Issue 4 July 2011 pp 899-905
Erbium (Er) and lanthanum (La) substituted BiFeO3 (BFO) ceramics have been prepared through conventional solid solution route. X-ray diffraction data indicated a gradual phase transition from rhombohedral to monoclinic structure in Bi0.9–𝑥 La0.1Er𝑥 FeO3 (𝑥 = 0.05, 0.07 and 0.1) (BLEFO𝑥 = 0.05, 0.07,0.1) ceramics. Differential thermal analysis (DTA) measurements of BFO samples showed a ferroelectric transition at 835°C, whereas it is shifted to 792°C for BLEFO𝑥 = 0.1. The Raman spectra of BLEFO𝑥 = 0.05,0.07,0.1 samples showed the shift of Raman modes to higher wavenumbers and suppression of A1 modes indicating decrease in ferroelectricity. The Raman spectra also indicated the structural transformation due to Er and La substitution in BFO. On subsequent erbium doping, the intrinsic dielectric constant is found to decrease from 68 (for pure BFO) to 52 for BLEFO𝑥 = 0.05 to 43 for BLEFO𝑥 = 0.07 but increased to 89 for BLEFO𝑥 = 0.1 when compared to pure BFO. The increase in Er content resulted in the increase in spontaneous magnetization (0.1178 emu/g at 8T for BLEFO𝑥 = 0.1) due to collapse of spin cycloid structure. Ferroelectric remnant polarization of BLEFO𝑥 = 0.05 and BLEFO𝑥 = 0.07 decreases when compared to pure BFO while small remnant polarization (close to paraelectric behaviour) is evident for BLEFO𝑥 = 0.1.
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