Effect of Zr, Sm and Gd Doped CoFe2O4 on Structural, Spectral and Magnetic Properties

In this work, cobalt composite nano ferrites with chemical formula CoZr 0.05-x RE x Fe 1.95 O 4 (x = 0 and 0.025 and RE = Sm, Gd) were prepared using sol-gel synthesis method and studied structural, optical and magnetic properties of them. The Rietveld assessment of XRD data validated the emergence of a single-phase cubic spinel configuration for all compounds. SEM has been used to study the surface morphology of the compounds. Energy gap has been estimated and the values are 2 eV, 1.8 eV and 1.6 eV for CoZr 0.05 Fe 2 O 4 , CoZr 0.025 Sm 0.025 Fe 1.95 O 4, and CoZr 0.025 Gd 0.025 Fe 1.95 O 4 compounds respectively. FTIR and Raman spectra confirmed the structure with the appearance of standard modes. The RE replacement in CoFe 2 O 4 ferrites has an intense impact on magnetic properties. With the substitution of Sm 3+ and Gd 3+ ions in cobalt-zirconium ferrite, there is a reduction in saturation magnetization (55 emu g −1 of CoZr 0.05 Fe 2 O 4 reduced to 25 emu g −1 for Gd 3+ and to 29 emu gm −1 for Sm 3+ ) as the size of crystallites decreases. A decrease in crystallite size correlates with an increase in the number of spin disorder occurrences in rare Earth-substituted cobalt-zirconium ferrite nanoparticles Further, the decrease in coercivity (2440 Oe of CoZr 0.05 Fe 2 O 4 reduced to 720 Oe for Gd 3+ and to 29 Oe for Sm 3+ with rare Earth element doping is due to the crystallite size and large lattice distortion showed an enhancement of magnetocrystalline anisotropy field which effects a shift of resonance frequencies from higher frequencies which is good for the memory storage devices.