| Summary: | 碩士 === 國立中央大學 === 物理研究所 === 95 === We report a systematic investigation of the magnetic properties of Ni
nanoparticles after three extents of oxidation. First we prepared two sizes
samples by PVD(physical vapor deposition). Then the samples were
oxidized by 25 days. A series of copper nanoparticles were oxided to form
core-shell structure.
We find that TB of the core-shell structure Ni /NiO(4.6nm) increases
50K, the TB of the other one sample(2nm) increases 20K. When temperature
is at 40 K, all of the sample have a peak in the field-cooled (FC)
temperature-dependent magnetization .When the NiO shell is wider, the
phenomenen is distincter.
By the NiO shell thickness from 0.13nm to 0.27nm, the maximum
coercivity of the sample(4.6nm) increases 1.5 times. In the same, by the NiO
shell thickness from 0.16nm to 0.3nm the the maximum coercivity of the
other sample(2nm) increased 4 times.
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