Correlation between Cation Distribution and Magnetic and Dielectric Properties of Dy3+-Substituted Fe-Rich Cobalt Ferrite

Designing electromagnetic materials, particularly those based on transition-metal-containing spinel ferrites, with a controlled structure, phase, and chemistry at the nanoscale dimensions while realizing enhanced electrical and magnetic properties continues to be a challenging problem. Herein, we report on the synthesis and structure- property correlation of dysprosium (Dy)-substituted iron-rich cobalt ferrite (Co0.8Fe2.2-xDyxO4; CFDO; x = 0.000-0.100) oxides with variable Dy-3(+) concentration. Chemical bonding analyses of CFDO nanomaterials using Raman spectroscopic analyses supported the spine' phase formation with high quality. Cation distribution determined from Mossbauer spectroscopy reveals the fact that Dy3+ occupies the octahedral site of the spinel lattice. Saturation magnetization (Ms) values calculated using Neel's two-sublattice model and cation distribution derived from Mossbauer's studies correlate well with the magnetization values obtained from SQUID measurements. The B-site hyperfine field decreases from 52.24 +/- 0.10 to 49.26 +/- 0.00 T, as evidenced by the Mossbauer spectra, with Dy substitution, which decreases the Fe-ion occupancy from the octahedral site of CFDO. Frequency-dependent dielectric constant indicates electron hopping in the grain interior, which ceases above 6.3 kHz. Dielectric measurements indicate that these CFDO compounds are useful for absorption at higher frequencies. Thus, using the combined approach based on Raman and Mossbauer spectroscopic analyses, the present work elucidates the structure, chemical bonding, and magnetic properties of Dy-substituted Fe-rich cobalt ferrite. CFDO may serve as a model system to apply to a class of Fe-rich ferromagnetic nanomaterials for electromagnetic and sensor applications.

Automated summary

This study reports the synthesis and structure-property correlation of dysprosium-substituted iron-rich cobalt ferrite. The chemical bonding and magnetic properties of the material were elucidated using Raman and Mossbauer spectroscopic analyses. These materials show potential for absorption at higher frequencies.