Materials Literature
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The influence of the harshness of the repulsive part of the pair potential on the onset of the process of homogeneous nucleation of the crystal from the supercooled liquid has been investigated using the computer simulation method of molecular dynamics. An inverse twelfth power and an inverse seventh power system were…
The coercivity and permeability of Fe-Si films can be improved by laminating several layers with either nonmagnetic (SiO2, Al2O3, Al or Mo) or ferromagnetic (Ni, Fe, Co or 20-wt. % Fe–Ni) spacers. It is also found that films made with soft magnetic laminations have an advantage over nonmagnetic or hard magnetic ones.…
The magnetic properties of rapidly quenched FeRM alloys where R=La,Y,Pr,Nd,Gd and M=B,Si,Al,Ga,Ge have been investigated over a wide range of chemical compositions. The samples are generally magnetically soft in the as-quenched state. Magnetic hardening is produced by annealing the samples around 700 °C. The best prop…
Mr=123.00, orthorhombic, Cmcm, Z=4; at 120K, a=6.713 (7), b=12.669 (4), c=5.968 (5) Aring, V=507.7 (7) Aring 3; at 295K, a=6.8018 (4), b=12.7132 (9), c=5.9990 (4), V=518.75 (6) Aring 3; m.p.=303.1K ...
The short-term stability of the magnetic field generated by permanent magnets is calculated on the basis of spin-wave theory. The results indicate that the relative rms fluctuation of the magnetic field is inversely proportional to V1/2H1/4e , where V is the magnet volume and He the effective magnetic field inside the…
The hexagonal compound Mn2Mo3O8 orders as a ferrimagnet but the spontaneous magnetization below TC is shown to reduce to zero as T → 0. This is possible according to the Néel collinear mean field model for ferrimagnets but has not been observed in single phase unmixed materials before. Magnetization results on single…
The saturation magnetostriction λs of a ferromagnetic material is measured by determining the strain that occurs when the saturation magnetization vector is rotated through 90°. However, the magnetostrictive strain responsible for transformer noise is the net strain measured parallel to the applied field when the mate…
The solution absorption spectrum of Bk3+(aquo) was measured and the observed band structure interpreted in terms of a free-ion energy level model. The band intensities were successfully analyzed using the Judd–Ofelt theory for transitions within the f N configuration. Parameters of the theory were then used to compute…
The crystal and magnetic structure of the hard magnetic alloy Mn1.074Al0.871C0.005, which has a body centered tetragonal structure, has been investigated. Neutron diffraction data shows that Mn0.992, C0.008 occupy the (0,0,0) site and Mn0.082, Al0.871, C0.047 occupy the ( 1/2 , 1/2 , 1/2 ) site. The magnetic moments o…
The effect of Zr on the hard magnetic properties of Sm(Co0.745−xFe0.200Cu0.055Zrx)7.5 permanent magnets has been examined by correlating the coercive field with the microstructure. Optical and transmission electron microscope studies show that Zr suppresses the precipitation of a SmCoCu phase and controls the size of…
A model is presented for the contribution of ground-state charge transfer between a metal and adsorbate to surface-enhanced Raman scattering (SERS). It is shown that this contribution can be understood using the vibronic theory for calculating Raman intensities. The enhancement is due to vibronic coupling of the molec…
The physical properties of vapor deposited amorphous solid water, (H2O)as, depend strongly on a parameter not investigated before: the state of the vapor prior to deposition on a cryoplate. Supersonic flow conditions give (H2O)as desposits with a very rugged surface, whereas breakup of supersonic flow by a baffle give…
A theoretical description of the static structural, vibrational, and solid-solid phase-transition properties of alkali halides is presented. The description is ab initio involving pseudopotentials and density-functional theory. Using NaCl as a prototypical example, we conclude that properties of alkali halides can be…
Raman spectra in superionic glasses ${(\mathrm{AgI})}_{x}{({\mathrm{Ag}}_{2}\mathrm{O}\ifmmode\cdot\else\textperiodcentered\fi{}n{\mathrm{B}}_{2}{\mathrm{O}}_{3})}_{1\ensuremath{-}x}$ for various values of $x$ ($0.1\ensuremath{\le}x\ensuremath{\le}0.55$) and for various $n (2\ensuremath{\le}n\ensuremath{\le}4)$ are re…
Growth of grains with sizes many times (>50×) larger than the film thickness and with uniform (111) texture, has been achieved in ultrathin (<100 nm) films of Si on SiO2. Growth of these secondary grains is driven by minimization of anisotropic surface energy. As a result, the secondary grain growth rate…
The temperature dependence of the x-ray structure factor has been measured for ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ and ${\mathrm{As}}_{x}{\mathrm{S}}_{1\ensuremath{-}x}$ glasses of compositions $x=0.40,0.33,0.19, \mathrm{and} 0.11$. In all of these glasses, a surprising increase in the first-diffraction-peak intens…
A new type of bolometer detector for the millimeter and submillimeter spectral range is described. The bolometer is constructed of silicon using integrated circuit fabrication techniques. Ion implantation is used to give controlled resistance vs temperature properties as well as extremely low 1/f noise contacts. The d…
Magnetic and crystallographic measurements have been carried out for Mn2−xMxSb (M=Ti, V, Cr, Fe, and Co) in order to study the nature of the transition from ferrimagnetic (Fr) to antiferromagnetic (AF) states. The magnetic phase diagrams have been determined. In the cases of M=Ti and Fe, only the Fr phase is observed.…
The electronic structure of carbon overlayers on Ni(111) has been investigated by using photoemission, energy-loss, and ionization-loss spectroscopy techniques. The combined use of these spectroscopies gives a detailed picture of these surfaces which have important catalytic implications. The carbidic carbon overlayer…
A model, based on the Sm-Co system between SmCo5 (1:5) and Sm2Co17 (2:17 R and 2:17 H), is proposed to describe the metallurgical behavior of Sm(Co,Fe,Cu,Zr)z alloys between 6.8<z<8.5 in the development of hard magnetic properties. The same phases are encountered in both the binary and multicomponent all…