Structure and magnetic properties of nano Co_1-xZn_xFe₂O₄/SiO₂ composites

Nano Co_1-xZn_xFe₂O₄/SiO₂ (0≤x≤1) composites were prepared by sol-gel method using teterathylor- thodilicate and nitrates as precursor in order to investigate the effect of Zn²⁺ content on the structure and magnetic properties of composites. The structure, morphology and magnetic properties of the composites were investigated by XRD, TEM, VSM and Mssbauer effect. The results show that Co_1-xZn_xFe₂O₄ grains distribute uniformly in nano Co_1-xZn_xFe₂O₄/SiO₂ composites and present cubic spine structure. The unit cell of Co_1-xZn_xFe₂O₄ expands after Zn²⁺ substituting Co²⁺. With the increasing of Zn²⁺ content, the coercivity of the composites decreases, and the value of saturation magnetization increases firstly then decreases, while the composites transform from magnetic order state into paramagnetic state. The doping of Zn²⁺ has more effect on the density of s-electron around Fe³⁺ nucleus, less effect on structural symmetry.