74,769 research outputs found
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
Surfactant induced smooth and symmetric interfaces in Cu/Co multilayers
In this work we studied Ag surfactant induced growth of Cu/Co multilayers.
The Cu/Co multilayers were deposited using Ag surfactant by ion beam sputtering
technique. It was found that Ag surfactant balances the asymmetry between the
surface free energy of Cu and Co. As a result, the Co-on-Cu and Cu-on-Co
interfaces become sharp and symmetric and thereby improve the thermal stability
of the multilayer. On the basis of obtained results, a mechanism leading to
symmetric and stable interfaces in Cu/Co multilayers is discussed.Comment: 7 Pages, 7 Figure
Weighted Density Approximation Description of Insulating YH and LaH
Density functional calculations within the weighted density approximation
(WDA) are presented for YH and LaH. We investigate some commonly used
pair-distribution functions G. These calculations show that within a consistent
density functional framework a substantial insulating gap can be obtained while
at the same time retaining structural properties in accord with experimental
data. Our WDA band structures agree with those of approximation very well,
but the calculated band gaps are still 1.0-2.0 eV smaller than experimental
findings.Comment: 6 Pages, 3 figure
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
Discovery of a remarkable subpulse drift pattern in PSR B0818-41
We report the discovery of a remarkable subpulse drift pattern in the
relatively less studied wide profile pulsar, B0818-41, using high sensitivity
GMRT observations. We find simultaneous occurrence of three drift regions with
two different drift rates: an inner region with steeper apparent drift rate
flanked on each side by a region of slower apparent drift rate. Furthermore,
these closely spaced drift bands always maintain a constant phase relationship.
Though these drift regions have significantly different values for the measured
P2, the measured P3 value is the same and equal to 18.3 P1. We interpret the
unique drift pattern of this pulsar as being created by the intersection of our
line of sight (LOS) with two conal rings on the polar cap of a fairly aligned
rotator (inclination angle alpha ~ 11 deg), with an ``inner'' LOS geometry
(impact angle beta ~ -5.4 deg). We argue that both the rings have the same
values for the carousel rotation periodicity P4 and the number of sparks Nsp.
We find that Nsp is 19-21 and show that it is very likely that, P4 is the same
as the measured P3, making it a truly unique pulsar. We present results from
simulations of the radiation pattern using the inferred parameters, that
support our interpretations and reproduce the average profile as well as the
observed features in the drift pattern quite well.Comment: 5 pages and 7 figures, Accepted for publication in MNRAS Letter
Cohesion of BaReH and BaMnH: Density Functional Calculations and Prediction of (MnH Salts
Density functional calculations are used to calculate the structural and
electronic properties of BaReH and to analyze the bonding in this compound.
The high coordination in BaReH is due to bonding between Re 5 states and
states of -like symmetry formed from combinations of H orbitals in the
H cage. This explains the structure of the material, its short bond lengths
and other physical properties, such as the high band gap. We compare with
results for hypothetical BaMnH, which we find to have similar bonding and
cohesion to the Re compound. This suggests that it may be possible to
synthesize (MnH salts. Depending on the particular cation, such salts
may have exceptionally high hydrogen contents, in excess of 10 weight
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Entropy scaling based viscosity predictions for hydrocarbon mixtures and diesel fuels up to extreme conditions
An entropy scaling based technique using the Perturbed-Chain Statistical Associating Fluid Theory is described for predicting the viscosity of hydrocarbon mixtures and diesel fuels up to high temperatures and high pressures. The compounds found in diesel fuels or hydrocarbon mixtures are represented as a single pseudo-component. The model is not fit to viscosity data but is predictive up to high temperatures and pressures with input of only two calculated or measured mixture properties: the number averaged molecular weight and hydrogen to carbon ratio. Viscosity is predicted less accurately when the mixture contains high concentrations of iso-alkanes and cyclohexanes. However, it is shown that predictions for these mixtures are improved by fitting a third parameter to a single viscosity data point at a chosen reference state. For hydrocarbon mixtures, viscosity is predicted with average mean absolute percent deviations (MAPDs) of 12.2% using the two-parameter model and 7.3% using the three-parameter model from 293 to 353 K and up to 1000 bar. For two different diesel fuels, viscosity is predicted with an average MAPD of 21.4% using the two-parameter model and 9.4% using the three-parameter model from 323 to 423 K and up to 3500 bar
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