Confined growth of highly uniform and single bcc-phased Fe Co/graphitic-shell nanocrystals in SBA-15

초록

We have synthesized highly uniform and single bcc-phased FeCo/graphitic carbon shell (FeCo/GC) nanocrystals with an average diameter of 5.7 +/- 0.3 nm by thermal decomposition of metal precursors in SBA-15 and subsequent methane CVD. Small-angle XRD data and N-2 adsorption-desorption isotherms of the SBA-15 before and after loading with FeCo/GC nanocrystals clearly demonstrate that the structure of SBA-15 was retained during the nanocrystal growth and most of the channels of the mesoporous silica were stucked by the FeCo/GC nanocrystals. The nanocrystal sizes of 5-6 nm are consistent with the pore diameters of the SBA-15. The yield of nanocrystals in silica has been increased 6-fold and the Fe/Co ratio of the FeCo/GC nanocrystals has been improved from 34:66 to 46:54 by using SBA-15 instead of fumed silica. The FeCo/GC nanocrystals exhibit superparamagnetism with high saturation magnetization of 209 emu/g metal at room temperature. (C) 2013 Elsevier Inc. All rights reserved.

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