Tuning the microstructural and magnetic properties of CoFe(2)O(4)/SiO(2) nanocomposites by Cu(2+) doping

Co–Cu ferrite is a promising functional material in many practical applications, and its physical properties can be tailored by changing its composition. In this work, Co(1−x)Cu(x)Fe(2)O(4) (0 ≤ x ≤ 0.3) nanoparticles (NPs) embedded in a SiO(2) matrix were prepared by a sol–gel method. The effect of a small Cu(2+) doping content on their microstructure and magnetic properties was studied using XRD, TEM, Mössbauer spectroscopy, and VSM. It was found that single cubic Co(1−x)Cu(x)Fe(2)O(4) ferrite was formed in amorphous SiO(2) matrix. The average crystallite size of Co(1−x)Cu(x)Fe(2)O(4) increased from 18 to 36 nm as Cu(2+) doping content x increased from 0 to 0.3. Mössbauer spectroscopy indicated that the occupancy of Cu(2+) ions at the octahedral B sites led to a slight deformation of octahedral symmetry, and Cu(2+)doping resulted in cation migration between octahedral A and tetrahedral B sites. With Cu(2+) content increasing, the saturation magnetization (M(s)) first increased, then tended to decrease, while the coercivity (H(c)) decreased continuously, which was associated with the cation migration. The results suggest that the Cu(2+) doping content in Co(1−x)Cu(x)Fe(2)O(4) NPs plays an important role in its magnetic properties.