Structural, vibrational, and enhanced magneto-electric coupling in Ho-substituted BiFeO3

Abstract The effect of Holmium (Ho) substitution in BiFeO 3 [Bi 1-x Ho x FeO 3 (x = 0.00, 0.05, 0.10, 0.15, 0.18, and 0.20)] ceramics is reported. The X-ray diffraction study shows composition-driven rhombohedral-to-orthorhombic ( R 3 c to Pnma ) phase transition for Bi 1-x Ho x FeO 3 (x = 0.15, 0.18, and 0.20) which is confirmed by Reitveld refinement. Raman spectra of Bi 1-x Ho x FeO 3 (x = 0.00, 0.05, and 0.10) belong to the rhombohedral ( R 3 c ) structure. Further increasing the Ho 3+ concentration in a BiFeO 3 (BFO) system revealed that Raman modes of Bi 1-x Ho x FeO 3 (x = 0.15, 0.18 and 0.20) were assigned to an orthorhombic ( pnma ) structure, which is confirmed by the Rietveld analysis of X-ray diffraction data and TEM analysis. Ferroelectric studies show that the remnant polarization (P r ) gradually decreases for Bi 1-x Ho x FeO 3 (x = 0.15, 0.18, and 0.20), confirming the transformation from polar to non-polar systems. Magnetic measurement shows ferromagnetic behavior observed for Bi 1-x Ho x FeO 3 (x = 0.10 and 0.20) samples. Further, the magneto-electric coupling is measured in terms of magneto-capacitance of Ho 3+ -substituted BiFeO 3 samples.