Crystal structure, magnetic and dielectric properties of Er-doped BiFeO${}_3$ ceramics

Er-doped BiFeO${}_3$ (BFO) ceramics have been synthesized to investigate their improved physical properties. The analysis of XRD patterns by Rietveld refinement revealed transformation in crystal structure from rhombohedral (x < 0.10, R3c) to mixed rhombohedral and orthorhombic (0.10 ≤ x ≤ 0.20, R3c + Pnma) phases. Electron density contours confirm the stabilization of the uniform and symmetric structures in the calculated profiles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the morphology of prepared ceramics. The presence of selective elements in prepared samples was confirmed by EDAX (Energy-dispersive analysis of X-ray). M-H loops depict significant enhancement in magnetic properties with doping of Er, which is suggested to be evolved via suppression of spin cycloid and reorientation of magnetic spins. The highest values of coercive field and remnant magnetization were observed for x = 0.20 (H${}_c$ = 0.35565$T,M$_r$ = 0.39774 emu/g). Dielectric measurements of all the ceramics, recorded in the frequency range from 100 Hz to 7MHz follow Maxwell-Wagner type dispersive behaviour. The Nyquist plot characteristics of the prepared Er doped BFO ceramics revealed non-Debye relaxation processes with negative (- ve) temperature coefficient of resistance (NCTR). All the prepared ceramics show polarization hysteresis loops (P-E). The obtained results show that these ceramics may be considered for designing novel smart systems.