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Formation of Ni/SiO2 and Ag/SiO2 Nanosphere Composites
Published online by Cambridge University Press: 17 March 2011
Abstract
SiO2 nanospheres have been produced via a high temperature evaporation process and they have been Ni or Ag plated using electroless plating solutions. These samples were examined by Atomic Force Microscopy (AFM) and Magnetic Resonance (MR). The initial SiO2 nanospheres were about 30 nm in diameter, and the Ni plating layer resulted in a 25nm thick metallic Ni coverage, while the Ag coverage was estimated to be in the 150 nm range. In the case of the Ni/SiO2 nanosphere composites, the MR signals show the presence of Ni+2 and Ni+3 paramagnetic centers, seen below 40K, and ferromagnetic metallic Ni, which is seen above 40K. The dried Ni plating solution (with no SiO2) shows only the presence of paramagnetic Ni+3. These results suggest that an interfacial reaction at the surface of the SiO2 nanospheres leads to the formation of ferromagnetic Ni, which deposits onto the spheres and forms a ferromagnetic Ni/SiO2 nanosphere composite. In the case of the Ag/SiO2 nanosphere composites, no MR signal is seen from the non-magnetic Ag, but strong paramagnetic behavior has been noted for Co+2, which originates from the plating solution.
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- Copyright © Materials Research Society 2002