Structural, magnetic and electrical properties of Ho and Ni Co-Doped BiFeO3 materials#

Abstract

Pure BiFeO3 (BFO) and Bi1-xHoxFe0.97Ni0.03O3 (x = 0,0.025, 0.05, 0.075, and 0.1) materials were synthesized by a sol-gel method. The influence of (Ho, Ni) co-doping on structural, magnetic and electrical properties of BFO materials were investigated by different techniques as X-ray diffraction (XRD), energy dispersion X-ray (EDX), Raman scattering, magnetic hysteresis (M-H) loops, and complex impedance spectra measurement. XRD results showed that all samples were crystallized in the rhombohedral structure with R3C space group. Crystal lattice parameters (a, c) and average crystal size LXRD were (a = 5.584 Å, c = 13.867 Å, LXRD = 60 nm) for pure BFO, (a = 5.589 Å, c = 13.875 Å, LXRD = 60 nm) for BiFe0.97Ni0.03O3 sample, and then decreased with increasing of Ho content in (Ho, Ni) co-doped samples. Similarly, Raman scattering spectra showed the left shift of active modes Fe-O bonds when doping Ni and right shift when co-doping Ho. These observations confirmed the successful substitution of Ho3+ and Ni2+ ions into the host BFO crystal lattice. Magnetic hysteresis loops measurement indicated that all samples exhibited weak ferromagnetic behavior with saturation magnetization Ms and remnant magnetization Mr of (Ms ~ 0.047 emu/g, Mr ~ 0.008 emu/g) for pure BFO which increased gradually for (Ho, Ni) co-doped samples, reached to (Ms ~ 0.702 emu/g, Mr ~ 0.169 emu/g) for x = 0 sample. Origin of the enhancement of ferromagnetization in (Ho, Ni) co-doped samples have been discussed.