Materials Literature
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The ordered structure of at 70 - 75 K has been studied by time-resolved neutron powder diffraction. The ordered superlattice has a structure with approximately four full D sites and one vacant D site in successive (420) planes, which is consistent with previous observations. Several superlattice lines not reported in…
The critical state (Bean) model for superconducting hysteresis is discussed for arbitrary specimen shapes and complex flux distributions. It is demonstrated that this model exhibits the ‘‘wiping out’’ property and ‘‘congruency’’ property of minor hysteresis loops. This leads to the conclusion that the critical state m…
In this paper, we have investigated experimentally the approach to the anhysteretic surface in M–H–σ space. In particular, for a 0.5 wt% carbon steel specimen, we have applied 73 MPa tension and a bias field H and determined the end flux density after superimposing an ac field of amplitude gradually decreasing to zero…
The Curie temperatures of several Nd2Fe17-based intermetallic compounds are calculated based on the spin-fluctuation model of Mohn and Wohlfarth and the band structure results calculated using the self-consistent orthogonalized linear combinations of the atomic orbitals method in the local spin density approximation.…
Magnequench NdFeB powders having high and low rare earth contents were explosively compacted to obtain cylindrical magnets. The magnetic properties were found to be isotropic and were superior to conventionally consolidated isotropic magnets. The (BH)max was 14.7 MGOe and the remanence was 8.7 kG for the explosively c…
Interpretation of Henkel plots in terms of the Preisach model is revisited. The Preisach model is treated as a purely phenomenological one and the Henkel plots are directly related to experimental data, namely, to the first-order transition curves.
Differential scanning calorimetric (DSC) studies have been carried out in an attempt to explain the composition dependence of the thermal crystallization behaviour of glasses. It is seen that these glasses exhibit a single glass transition and single-stage crystallization on heating. The glass transition temperature,…
Magnetic properties of YFe2 and its deuterides YFe2Dx have been investigated in the temperature range 300<T<800 K. Both the lattice structure and the Curie temperature Tc show strong dependence on the deuterium composition x. The deuterides have a C15 cubic structure up to x=2.7 and Tc rises from 560 K f…
Power losses in a magnetostrictive actuator have been studied. The system consists of a cylindrical rod of Terfenol-D, a surrounding magnetic circuit to get a homogeneous flux, a mechanical load applied to the rod ends, and an electric coil. We consider transient operating conditions with time-varying driving voltage.…
α-Fe powder has been ball milled at room temperature in an anhydrous ammonia atmosphere for various times. The composition and structure of milled powders was investigated using x-ray diffraction spectroscopy, Mössbauer spectroscopy, combustion elemental analysis, and thermal analysis. A high temperature reaction sequ…
The temperature dependence of the specific heat shows that the strong electron-phonon coupling system HfV2 undergoes a structural transformation at 116 K and becomes superconducting around 9 K. The structural instability can be interpreted in terms of a strong electron-phonon coupling and Fermi surface nesting. The st…
Magnetic power losses have been experimentally investigated and theoretically predicted over a range of frequencies (direct current—1.5 kHz) and peak inductions (0.5–1.5 T) in 1-mm-thick FeSi 2 wt. % laminations. The direct current hysteresis properties of the system are described by the Preisach model, with the Preis…
Ni K-edge x-ray-absorption spectroscopy (XAS) measurements on a series of perovskite-layer-based nickelate compounds, with varying formal Ni valence, are presented. Spectral features that vary systematically with the Ni configuration are identified for these Ruddlesden-Popper phase and Sr substituted ${\mathrm{Ln}}_{2…
Observation of tip-induced transformation of a graphite superlattice to triangular dislocations is reported here. The transformation took place as the misorientation angle of the top layer decreased and the superlattice spacing increased. The area of the triangles increased with each scan. \textcopyright{} 1996 The Am…
Materials with a large capacity to dissipate mechanical energy are of interest for passive vibration damping. We have measured the zero-field damping capacity of the giant magnetostrictive terbium–dysprosium–iron compounds by quasistatic stress–strain hysteresis loops. The magnetization and strain of the samples were…
Pulsed laser deposition using bulk NiOFe2O3 targets onto heated substrates has been used to synthesize single phase Ni spinel ferrite films onto various substrates. Flowing oxygen has been used during the deposition to maintain the oxygen stoichiometry. Ni ferrite films have been deposited onto C-, R-, and A-plane sap…
RFe7 compounds with the TbCu7 structure have been synthesized by annealing of mechanically alloyed powders. The lattice constants a and c decrease with increasing atomic number of the rare earths except for Ce which has a different valence state. Introduction of nitrogen interstitial atoms into the structure results i…
Mechanically alloyed magnets SmCox (x=6.0–11.0) have been prepared using starting materials of commercial SmCo5 and Co powders. X-ray diffraction data indicate that the equilibrium Sm2Co17 phase can be achieved in a nanocomposite Sm2Co17/Co system at x=8.5–11.0, while a Sm2Co17/SmCo5 structure occurs at x=6.0–8.0. The…
We present a potential-energy function for H interacting with bulk metallic Ni. The potential is parametrized to be accurate both for H adsorbed on Ni surfaces and for H absorbed at interior sites. The function introduces a nonlocal density dependence into the embedded-atom method formalism. We show that the function…
Self-consistent spin–polarized electronic structure calculations have been carried out to derive the magnetic properties of the Sm2Fe17−xAx (A=Al, Ga, Si and x=0 and 1). The influence of impurities on the Curie temperature (TC) of Sm2Fe17 has been studied using the spin–fluctuation approach of Mohn and Wohlfarth. The…