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キーワード:
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要旨:
We report the first study on the chemical preparation, structural
characterization, and magnetic properties of Co2NiGa nanopartides (NPs)
of a single gamma-phase (gamma-Co2NiGa). The gamma-Co2NiGa NPs were
prepared by impregnation in colloidal silica followed by high
temperature annealing under hydrogen atmosphere. The crystal structure
of tetragonal gamma-Co2NiGa was confirmed by selected area electron and
X-ray diffraction studies. Energy-dispersive X-ray spectroscopy mapping
and X-ray absorption near edge structure data provided evidence for the
successful preparation of the intermetallic NPs and the absence of Co,
Ni, Co-Ni, or metal-containing impurity phases. Extended X-ray
absorption fine structure spectroscopy data confirmed the formation of
the gamma-Co2NiGa phase by examining the atomic environments surrounding
Co, Ni, and Ga. The Co2NiGa NPs are ferromagnetic with a high saturation
magnetization, which is consistent with the theoretical model.
gamma-Co2NiGa NPs exhibit a very high Curie temperature (approximate to
J1139 K), which make them promising candidates for high temperature
magnetically activated nanoscale devices.
