Structural and magnetic properties of Gd3+ substituted Nanocrystalline Cobalt Ferrite
Abstract
In this study, we have investigated the impact of Gd3+ substitution on the structural and magnetic properties of the spinel cobalt ferrite CoFe2-xGdxO4 (x=0.05, 0.10, 0.15, and 0.20) which was synthesized by using the citrate precursor sol-gel technique and then control annealed at 750 °C. The gross-structural characteristics of the nanoparticles confirmed spinel crystal symmetry with the space group Fd3m. The Williamson-Hall (W-H) plot shows maximum value of lattice strain 2.71×10-3 for CoFe1.85Gd0.15O4. The lattice parameter (a) shows a discernible increase as a result of induced strains. The lengths of the tetrahedral and octahedral M-O bonds are determined by the FTIR. The "Law of Approach to Saturation" quantifies that with an increase in Gd3+ concentration, saturation magnetization (Ms), Coercivity (Hc) and magneto-anisotropy (k1) decreases from 73.16 to 49.89 emu/g, 1452 to 989 Gauss and 9.22 to 3.22×106 erg/cm3, respectively. We have investigated a relationship between induced lattice strain and magnetic response for CoFe2-xGdxO4 with Gd=0.05 to 0.20. The very high coercivity of 1441 Gauss suggests employing such materials for the permanent magnet and high-density magnetic recording medium.