科研之友
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摘要
Using a chemically induced transition method in FeCl2 solution, gamma-Fe2O3 based magnetic nanoparticles, in which gamma-Fe2O3 crystallites were coated with FeCl3 center dot 6H(2)O, were prepared. During the synthesis of the gamma-Fe2O3 nanoparticles Cu(I) modification of the particles was attempted. According to the results from both magnetization measurements and structural characterization, it was judged that a magnetic silent "dead layer", which can be attributed to spin disorder in the surface of the gamma-Fe2O3 crystallites due to breaking of the crystal symmetry, existed in the unmodified particles. For the Cu(I)-modified sample, the CuCl thin layer on the gamma-Fe2O3 crystallites incurred the crystal symmetry to reduce the spin disorder, which "awakened" the "dead layer" on the surface of the gamma-Fe2O3 crystallites, enhancing the apparent magnetization of the Cu(I)-modified nanoparticles. It was determined that the surface spin disorder of the magnetic crystallite could be related to the coating layer on the crystallite, and can be modified by altering the coating layer to enhance the effective magnetization of the magnetic nanoparticles.
