Materials Literature
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Thin films of vanadium dioxide exhibit a thermally induced semiconductor-to-metal phase transition near 67 degrees C. In most deposition conditions, the transition is accompanied by large changes in optical properties at infrared wavelengths, but with only slight visible contrast. Recently, reactive evaporation at hig…
Using Preisach’s model, general expressions for hysteretic energy losses are derived. These expressions are valid for arbitrary (not necessarily periodic) variations of magnetic field. Moreover, these expressions are given in terms of Preisach’s function as well as in terms of experimentally measured ‘‘first-order tra…
Energy spectral properties in one-dimensional quasi-crystalline and incommensurate systems are studied numerically. It is known that the critical state, which is intermediate between the localized and the extended ones, occurs in these models. We find that those critical states are well characterized in common by the…
We have examined the effect of growth temperature and growth interruption time on molecular-beam-epitaxial growth of GaAs, Al0.3Ga0.7As, and InxGa1−xAs on GaAs substrates and In0.53Ga0.47As and In0.52Al0.48As on InP substrates using dynamical reflection high-energy electron diffraction as an in situ probe. We have stu…
Pronounced Fano-like resonant effects are observed in the photoemission spectra of the localized U 5f and O?p ndash---U?f,6d--- bonding bands of ${\mathrm{UO}}_{2}$ when photon energies near the U 5${d}_{3/2}$,5/2 thresholds (105 and 97.1 eV, respectively) are employed. The constant-final-state spectra are well descri…
Alternate layers of Co and Cu of individual layer thicknesses from 1.5 to 8.0 nm and total thickness of about 100 layers and of Co bilayers separated by Cu have been electroplated from an electrolyte having a low concentration of Cu and a high concentration of Co atoms. The properties of the resulting structures have…
The corrosion characteristics of RE-Fe-B magnets in elevated temperature and/or high humidity and salt-containing environments are reported. Magnetic properties, magnet integrity, and corrosion product were evaluated. Methods of improving the corrosion resistance of RE-Fe-B magnets were also investigated. Epoxy-type c…
Hysteresis does not vanish in materials essentially free from defects and domain wall pinning. It arises from the existence of many geometrically different domain structures separated by intrinsic energy barriers. Although generally metastable, these states can nevertheless be explored by suitable excursion in the man…
The temperature difference method was applied to grow a large single crystal of cubic boron nitride (cBN) under ∼55 kbar and ∼1800 °C using LiCaBN2 as a solvent. The effect of supersaturation of boron and nitrogen atoms in the solvent was studied by changing the temperature difference. The observed difference of the s…
A vector hysteresis model for particulate media has been developed and applied to a two-dimensional, self-consistent simulation of the magnetic recording process. Vector modeling is accomplished using a scalar Preisach model recording process. Vector modeling is accomplished using a scalar Preisach model for each of t…
The interaction of sulfur-containing molecules with titanium oxide surfaces is of significant technological importance since ${\mathrm{TiO}}_{2}$ is a widely studied catalyst support and sulfur is a notorious catalyst poison. We report here a study of the interaction of sulfur dioxide with both nearly perfect and high…
The magnetostriction of a single crystal of Tb0.27Dy0.73Fe1.95 grown by the Bridgman technique was measured over the temperature range of magnetic anisotropy compensation (300–330 K). Using a growth rate of 3 cm/h, twinned dendrites were suppressed. We looked for, but found no evidence of, modification of the cubic st…
Hard-carbon films prepared by the rf-plasma decomposition of acetylene have been investigated by high-resolution 13C nuclear magnetic resonance spectroscopy, x-ray photoelectron spectroscopy (XPS), and the H(15Nα,γ)C nuclear resonant reaction. It was found that the ratio of sp2:sp3 bound carbon was 1.6, and that virtu…
Neutron diffraction studies have been made on the intermetallic compounds, ErFe2Ni, ErFe1.5Ni1.5, and ErFeNi2, to determine the effect of the nonmagnetic Ni atoms on the three magnetic phases of ErFe3. Diffraction patterns above the Curie temperature show that Ni atoms almost exclusively occupy the h1 sites. At room t…
By modifying the microstructure (a/H) and magnetocrystalline anisotropy (b/H2) terms of the approach-to-saturation (ATS) law, the range of fields over which these terms remain finite is extended to low fields and a good approximation to the hysteresis loop may be constructed in its entirety. The model involves the int…
In order to study the local atomic environments of both B and Fe in Fe3B1−xCx (0.1≤x≤0.4), NMR measurements of the hyperfine field distributions for 10B, 11B, and 57Fe have been performed at 4.2 K and from 10 to 60 MHz. It was found that the 11B and 57Fe NMR frequencies do not change with C concentration. From these r…
Extensive study was made on Fe-base crystalline alloys in search for new soft magnetic materials with high saturation magnetization by means of sputtering technique. It revealed that newly found FeGaSi and FeAlGe alloy systems possessed excellent soft magnetic properties with remarkably higher saturation magnetization…
Dislocations affect the magnetic properties of ferromagnetic materials by pinning the domain walls. The primary mechanism is interaction between the stress fields of dislocation and domain walls. Using magnetic nondestructive methods, namely the acoustic Barkhausen noise (AB), magnetic Barkhausen noise (MB), and the h…
Differential scanning calorimetry (DSC) has been employed to study the changes which occur in the powders used to prepare Fe-R-B permanent magnets upon heating. Three exothermic reactions are observed upon heating the powders. The correlation of DSC data with the magnetic properties of Fe-R-B powders shows that these…
Mn-Al films have been prepared by dc magnetron sputtering and their crystallographic characteristics, magnetic properties, electrical resistivity, and internal stress have been investigated. The films deposited when substrate temperature Ts was below 100 °C and above 170 °C exhibit a high-temperature ε phase and β-Mn–…