Structural and magnetic influence of yttrium-for-iron substitution in cobalt ferrite

• CoYxFe1.98-xO4, x = 0; 0.1; 0.2; 0.3, were prepared by sol-gel.
• A slight iron deficiency in the formulation was designed to improve Y solubility.
• Yttrium enters the lattice in octahedral sites.
• Ms and Tc decrease with iron substitution, confirming the B site occupancy of Y ions.
• Y inclusion modifies Raman spectra, and new vibrational modes appear.

Yttrium-substituted cobalt ferrites of nominal composition CoYxFe1.98-xO4, x = 0; 0.1; 0.2; 0.3, were prepared using the sol-gel combustion method. A slight iron deficiency in the formulation was designed in order to improve yttrium solubility in the spinel structure. The inclusion of Y in the lattice reached 10% cationic substitution. XRD Rietveld analysis and Raman spectra confirm that yttrium enters the lattice in octahedral sites, increasing the inversion parameter of cobalt ferrite. Mössbauer results confirm the cation distribution obtained with Rietveld refinements. Saturation magnetization and Curie temperature decrease with iron substitution, confirming the B site occupancy of Y ions. Yttrium inclusion promotes a cation distribution which modifies the Raman spectra. A model is proposed to explain the observed vibrational modes.