Study of Magnetic and Temperature-Dependent Dielectric Properties of Co-CuFe2O4 Nanoferrites

The present study focuses on the investigation of magnetic and temperature-dependent dielectric properties of Co-CuFe2O4 nanoferrites. CuFe2O4, Cu0.5Co0.5Fe2O4 and CoFe2O4 nanoparticles were prepared using sol-gel auto-combustion. X-ray diffraction (XRD) pattern shows a phase transformation from tetragonal (for CuFe2O4) to cubic (for Cu0.5Co0.5Fe2O4 and CoFe2O4) structure. Surface morphology of synthesized samples was analyzed by scanning electron microscopy, which shows formation of agglomerated, irregular shaped nanoparticles. Fourier transform infrared and Raman spectra of CuFe2O4, Cu0.5Co0.5Fe2O4 and CoFe2O4 nanoparticles support the results of XRD analysis. The UV-visible spectra of all the samples show strong absorption maxima in the visible range and are used to calculate the energy band gap of the synthesized nanoferrites. It was noticed that the value of band gap is highest for CuFe2O4 (1.58 +/- 0.02 eV) nanoparticles in comparison to Cu0.5Co0.5Fe2O4 (1.18 +/- 0.02 eV) and CoFe2O4 (1.01 +/- 0.02 eV) ferrite systems. Magnetic study shows the highest value of coercivity (H e ) and squareness ratio (S) for Cu0.5Co0.5Fe2O4 (H-c = 959.10 +/- 0.30 Oe, and S= 0.45 +/- 0.05) ferrite. The dielectric measurement revealed a significantly lower value of tangent loss (tan delta) at higher frequencies for Cu0.5Co0.5Fe2O4 and CoFe2O4 ferrite samples in comparison to that for CuFe2O4. The high value of magnetic parameters, high resistivity (similar to 10(7)-10(8) Omega cm), and low dielectric loss at high frequencies for Cu0.5Co0.5Fe2O4 and CoFe2O4 nanoferrites suggests that the materials are potential candidate for high density magnetic recording media and also to be used in power transformers at high frequencies.