60 research outputs found
Phase formation, thermal stability and magnetic moment of cobalt nitride thin films
Cobalt nitride (Co-N) thin films prepared using a reactive magnetron
sputtering process by varying the relative nitrogen gas flow (\pn) are studied
in this work. As \pn~increases, Co(N), \tcn, CoN and CoN phases are formed.
An incremental increase in \pn, after emergence of \tcn~phase at \pn=10\p,
results in a continuous expansion in the lattice constant () of \tcn. For
\pn=30\p, maximizes and becomes comparable to its theoretical value. An
expansion in of \tcn, results in an enhancement of magnetic moment, to the
extent that it becomes even larger than pure Co. Though such higher (than pure
metal) magnetic moment for FeN thin films have been theoretically predicted
and evidenced experimentally, higher (than pure Co) magnetic moment are
evidenced in this work and explained in terms of large-volume high-moment model
for tetra metal nitrides.Comment: 4 pages, 4 figure
Phase composition of iron oxide nanoparticles studied using hard X-ray absorption spectroscopy
At the surface of iron oxide nanoparticles, an oxidized or disordered layer is often found. Due to the large surface-to-volume ratio of nanomaterials, such a surface layer plays an important role in the overall magnetic properties of the particles. Consequently, it is important to characterize the surface layer if applications of iron oxide nanoparticles, e.g., for magnetic hyperthermia, magnetic particle imaging, or ferrofluidics, are envisaged. In this work, we tuned the phase of the surface layer of 14 nm iron oxide nanoparticles via annealing procedures. The phase composition of the particles is systematically studied using hard X-ray absorption spectroscopy
Effect of dopants on thermal stability and self-diffusion in iron nitride thin films
We studied the effect of dopants (Al, Ti, Zr) on the thermal stability of
iron nitride thin films prepared using a dc magnetron sputtering technique.
Structure and magnetic characterization of deposited samples reveal that the
thermal stability together with soft magnetic properties of iron nitride thin
films get significantly improved with doping. To understand the observed
results, detailed Fe and N self-diffusion measurements were performed. It was
observed that N self-diffusion gets suppressed with Al doping whereas Ti or Zr
doping results in somewhat faster N diffusion. On the other hand Fe
self-diffusion seems to get suppressed with any dopant of which heat of nitride
formation is significantly smaller than that of iron nitride. Importantly, it
was observed that N self-diffusion plays only a trivial role, as compared to Fe
self-diffusion, in affecting the thermal stability of iron nitride thin films.
Based on the obtained results effect of dopants on self-diffusion process is
discussed.Comment: 10 pages, 9 fig
Formation of iron nitride thin films with Al and Ti additives
In this work we investigate the process of iron nitride (Fe-N) phase
formation using 2 at.% Al or 2 at.% Ti as additives. The samples were prepared
with a magnetron sputtering technique using different amount of nitrogen during
the deposition process. The nitrogen partial pressure (\pn) was varied between
0-50% (rest Argon) and the targets of pure Fe, [Fe+Ti] and [Fe+Al] were
sputtered. The addition of small amount of Ti or Al results in improved
soft-magnetic properties when sputtered using \pn 10\p. When \pn is
increased to 50\p non-magnetic Fe-N phases are formed. We found that iron
mononitride (FeN) phases (N at% 50) are formed with Al or Ti addition at
\pn =50% whereas in absence of such addition \eFeN phases (N\pat30) are
formed. It was found that the overall nitrogen content can be increased
significantly with Al or Ti additions. On the basis of obtained result we
propose a mechanism describing formation of Fe-N phases Al and Ti additives.Comment: 9 Pages, 7 Figure
Fe and N self-diffusion in non-magnetic Fe:N
Fe and N self-diffusion in non-magnetic FeN has been studied using neutron
reflectivity. The isotope labelled multilayers, FeN/57Fe:N and Fe:N/Fe:15N were
prepared using magnetron sputtering. It was remarkable to observe that N
diffusion was slower compared to Fe while the atomic size of Fe is larger
compared to N. An attempt has been made to understand the diffusion of Fe and N
in non-magnetic Fe:N
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