Effect of Surface Modifications on the Magnetic Properties of Ni_0.5Zn_0.5Fe₂O₄ Nanoparticles

Wei Zhang1,2),Hongxia Wang2,3),Faling Zhang2,4),Zhengnan Qian2) and Wenhui Su2) 1) School of Materials Science and Engineering,Hebei University of Technology,Tianjin 300130,China 2) Center for the Condensed-Matter Science and Technology,Department of Physics,Harbin Institute of Technology,Harbin 150001,China 3) Department of Chemistry,Harbin Normal University,Harbin 150001,China 4) Department of Physics,Jiangsu University,Zhenjiang 212013,China

摘 要：Two different silica sources have been used for the preparation of Ni0.5Zn0.5Fe2O4/SiO2 nanocomposites,and their effects on the particle size,crystallinity and the magnetic properties have been investigated by Xray diffraction(XRD),transmission electron microscopy(TEM) and physical property measurement system(PPMS).In both cases,Ni0.5Zn0.5Fe2O4 nanoparticles of 11 nm in mean particle size were well dispersed in silica matrix.The coercivity and the blocking temperature of Ni0.5Zn0.5Fe2O4 nanoparticles modified with the silicon coupling agent show little decrease,whereas the saturation magnetization increases obviously with respect to nanoparticles dispersed directly in silica matrix.It is considered that the decrease of the surface anisotropy resulting from the change in the surface coordination is responsible for the observed behavior.

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