A comparative study on structural, magnetic and optical properties of rare earth ions substituted Bi1−x R x FeO3 (R: Ce3+, Sm3+ and Dy3+) nanoparticles

Abstract

Abstract A comparative study on the manifestation of rare earth ions substitution induced alteration in structure, magnetic and optical properties of BiFeO3 nanoparticles was done. Sol-gel technique was employed to synthesize Bi1−x R x FeO3 (x = 0.05 and 0.10; R: Ce3+, Sm3+ and Dy3+) nanoparticles. X-ray diffraction patterns and Raman spectra analysis confirmed substitution driven structural phase transformation from distorted rhombohedral structure to orthorhombic structure for x = 0.10 samples. The enhanced magnetic properties with weak ferromagnetic behaviour were observed with increasing concentration of rare earth ions in BiFeO3 nanoparticles. The improved magnetic characteristics are attributed to many factors such as the uncompensated surface spins in nanoparticles, breaking of spin cycloid with R 3+ ions substitution and super exchange interaction between R 3+ and Fe3+ ions. The maximum magnetization values of 1.77 emu g−1, 1.87 emu g−1 and 5.5 emu g−1 were observed for x = 0.10 samples with Ce3+, Sm3+ and Dy3+ substitution, respectively. The magnetization increased with increasing difference in ionic radii of host Bi3+ (1.17 Å) ion and dopant Ce3+ (1.14 Å), Sm3+ (1.08 Å) and Dy3+ (1.03 Å) ions. UV–Visible diffuse reflectance spectra showed a sharp absorption in visible region and energy band gap values variation in the range 2.2 eV–2.33 eV.