Abstract
Cobalt nickel nanoferrites doped with dysprosium with nominal composition Ni0.4Co0.6DyyFe2-yO4 (where y = 0.0, 0.03, 0.06, 0.09, 0.12 and 0.15) were prepared by micro- emulsion method. The annealing temperature was determined from thermogravimetric analysis (TGA) data. X-ray diffraction (XRD) studies showed a prominent 311 peak which is a characteristic of simple spinel phase and is strong evidence of face centered cubic structure. X-ray studies also demonstrated that these ferrites have crystallite sizes in the range of 25-40 nm. Fourier transform infrared (FTIR) studies confirmed the presence of Dy3+ in place of Fe3+ in these ferrites. Two prominent peaks were appeared in the octahedral range of 350-500 cm(-1) in FTIR spectra. Dielectric studies revealed the significant decrease in dielectric constant and other dielectric parameters with the increased Dy3+ ions. The materials with minimum dielectric loss are required for high frequency devices fabrication. DC-electrical resistivity was also recorded at varied temperature in the range of 298 to 572 K.Ni0.4Co0.6Fe2O4 exhibited the DC resistivity 6.30x10(8) Omega cm while significant increase (similar to 10 %) in this value (6.90x10(8) Omega cm) was observed for Ni0.4Co0.6Dy0.15Fe1.85O4 nano-ferrites.