Materials Literature
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We have made time-of-flight neutron diffraction measurements on α-manganese metal. Powder diffraction measurements were made at 14 temperatures between 15 and 305 K, and single crystal measurements were made at 15 and 300 K. We found that the crystal structure of α-Mn is tetragonal below its Néel point of 100 K, with…
Abstract Sorption and transport properties of water through films of Nylon‐6 were obtained at 5, 23, and 40°C. Commercially available films were used and a Cahn electrobalance was employed for measuring the water uptake by the polymer samples. Values of the water sorption isotherms are accurately described by the Lang…
As an attempt to establish a unified treatise of the structure of amorphous germanium, silicon, and (tetrahedral) carbon, a series of reverse Monte Carlo simulations were carried out for all of the three materials. A number of constraints have been applied during the calculations in order to test how many (and how muc…
We have used the empirical pseudopotential method to study the electronic and optical properties of [001] Si quantum wires with (110)--(1\ifmmode\bar\else\textasciimacron\fi{}10) square cross sections ranging from 4\ifmmode\times\else\texttimes\fi{}4 to 14\ifmmode\times\else\texttimes\fi{}14 monolayers (7.7\ifmmode\ti…
Cobalt particles were prepared with the microemulsion method in the binary system of DDAB (didodecyldimethylammonium bromide)/toluene by reduction of CoCl2 with NaBH4. The average particle size of the as-prepared samples could be varied from 1.8 to 4.4 nm by controlling the concentration of CoCl2 in the solution of DD…
Amorphous magnetostrictive films of the binary compound SmxFe1−x as well as of the ternary compound (TbyDy1−y)xFe1−x were prepared by rf or dc magnetron sputtering using either a multitarget arrangement with pure element targets or cast composite-type targets. The magnetostrictive properties of (Tb0.3Dy0.7)0.4Fe0.6 an…
The self-assembled network of conducting polyaniline (PANI), protonated by camphor sulfonic acid (CSA), in a matrix of insulating polymethylmethacrylate (PMMA) has a remarkably low percolation threshold. The critical volume fraction (f) of the PANI-CSA phase segregated in PMMA is inferred from the concentration depend…
In order to determine the value of the intrinsic magnetic moment of the α ″ phase, the films of nitrogen-martensite with various N content were fabricated under various reactive sputtering conditions. The magnetic moment of (α ″+α′)-Fe16N2 films is discussed in connection with the change of the unit-cell volume of the…
Raman spectra of purified carbon deposits containing multishelled carbon nanotubes of average diameter 10--12 nm show narrow vibrational bands and no phonon softening in contrast to unpurified material. This is in agreement with lattice-dynamical calculations using a semiempirical pseudopotential, which predicts no si…
Luminescence excitation spectra are employed to study the electronic states of CdSe nanocrystals ranging in size from 9 to 26 Å radius at 77 K. These studies show that all samples have, in addition to the discrete manifold of quantum confined electronic excitations, a threshold for continuum absorption. Absorption int…
Micromagnetic calculations are used to investigate coercivity and energy products of magnets consisting of an aligned hard-magnetic skeleton phase and a soft-magnetic phase with high saturation magnetization. Compared to the present-day theoretical limit of 516 kJ/m3 for single-phase Nd2Fe14B, the energy product in su…
Nb-doped SrTiO3 (STO) thin films (Nb, 0<x<100 mol%) with a-axis orientation have been prepared on nondoped STO (100) and LaAlO3 (100) single crystals using a pulsed laser deposition technique. Solid-solution films are formed between STO and SrNbO3 without any impurity phases. Electrical conductivities of…
Micromagnetic calculations using a finite element technique rigorously describe the magnetic properties of novel, isotropic rare-earth-based composite magnets. Numerical results obtained for a composite material of Nd2Fe14B, SmCo5 or Sm2(Fe0.8Co0.2)17N2.8 and α-Fe particles show that remanence, coercivity, and coerciv…
A colossal magnetoresistance effect with more than a thousandfold change in resistivity (ΔR/RH=127 000% at 77 K, H=6 T) has been obtained in epitaxially grown La-Ca-Mn-O thin films. The effect is negative and isotropic with respect to the field orientations. The magnetoresistance is strongly temperature dependent, and…
Landau quantization of the \ensuremath{\pi} energy bands of a carbon nanotube is calculated within the tight-binding approximation. The energy bands do not show explicit Landau levels, but they do have energy dispersion for all values of magnetic field. The energy bandwidth shows oscillations with a period that is sca…
The 1.681-eV luminescence center characteristically observed in chemical-vapor-deposited diamond films is studied in a homoepitaxially grown diamond film. Homoepitaxial growth relaxes the strain typical for films grown on heterosubstrates with lattice mismatch, thus reducing dramatically the optical linewidths down to…
Though the anomalous antiferromagnetism of zinc ferrite was a subject of intensive studies in the past, the unusually high magnetization of coprecipitated zinc ferrite at low temperatures has drawn renewed interest among researchers. The local structures of zinc ferrites around Fe and Zn atoms are measured using exten…
An extension of the hysteresis model has been developed that takes into account the effects on the hysteresis curves of eddy currents in electrically conducting media. In the derivation presented it is assumed that the frequency of the applied field is low enough (or the thickness of the material medium small enough)…
Giant magnetotransport phenomena including the field-induced nonmetal-metal transition have been found in single crystals of La 1- x Sr x MnO 3 near the critical composition ( x ≈0.17) for the nonmetal-metal transition and in the temperature region around the magnetic phase transition. Change of the resistivity shows…
The planarity of the aromatic stage of two-dimensional Si and Ge layers are theoretically investigated by first-principles total-energy calculations. While a C atom prefers to form the flat aromatic stage, i.e., graphite, Si and Ge prefer to form the corrugated aromatic stage. Si can be said to be the critical element…