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Abstract:
Nanoparticles of solid solution Fe (x) Pt(1-x) , where 0.25a parts per
thousand yenxa parts per thousand yen0 ( fcc lattice) with
gamma-Fe(2)O(3) shell (lattice of the spinel type) were synthesised and
characterised by high-resolution transmission electron microscopy,
energy dispersive X-ray analysis, electron energy loss spectroscopy,
Mossbauer spectroscopy and magnetometry. From the point of view of
magnetic properties, such two-phase particles are interesting because
their core is antiferromagnetic or paramagnetic (at very small values of
x) whereas the shell is ferrimagnetic. The size of the particles was in
the range of several nanometers. The Mossbauer measurements revealed a
blocking temperature of about 100 K above which the particles are
superparamagnetic. Towards lower temperatures, the magnetic
characteristics of an ensemble of such particles show an increase of
magnetic rigidity.