LAUSR

Abstract ZnxCo1-xFe2O4/SiO2 (x = 0, 0.25, 0.50, 0.75, 1.00) nanocomposites (NCs) have been investigated through structural, morphological and magnetic measurements. X-ray diffraction and Mossbauer data indicated the presence of nanocrystalline mixed cubic spinel. The lattice parameters gradually decreased with increasing Zn content and follow Vegard's law. The crystallite size, X-ray density and porosity of ZnxCo1-xFe2O4 decreased with increasing Zn content. The ferrite nanoparticles spherical shape and size (32.0–6.5, 17.5–8.1 and 36.2–18.6 nm for the NCs annealed at 500, 800 and 1100 °C, respectively) was established by transmission electron microscopy. The Mossbauer spectra showed the characteristic magnetic patterns of Co and Zn spinels. The shape of hysteresis loops revealed the dependence of superparamagnetic behavior on the structural properties. The saturation magnetization (Ms) and coercive field (Hc) were also influenced by Co substitution with Zn, showing the decrease of Ms and Hc. The replacement of magnetic Co2+ with the zero magnetic moment Zn2+ induces a gradual reduction of magnetocrystalline anisotropy and decrease of Hc.