Materials Literature
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Magnetic measurements were performed on Sr-hexaferrites of type Me2+2–Sr(W) with Me2+2=Fe2+, Ni2+, Co2+, Zn2+, and Me2+-Sr(X) with Me2+=Fe2+, Zn2+ in the temperature range 5K 750 K. The Curie temperatures are found to be 781 and 721 K for Fe2-Sr(W) and Fe-Sr(X) systems, respectively. The saturation magnetization of a…
Monodispersed polystyrene spheres with diameters in the μm range are mixed with magnetic fluid and confined to thin layers between two glass plates. In an external magnetic field H, polarization of the magnetic fluid produces an apparent magnetic moment Mv associated with each sphere due to the displaced volume V. For…
A theory for Auger line shapes in alloys is presented and applied to dilute alloys with "free-electron"-like and "noble-metal"-like hosts. For noble-metal-like hosts, we show that anomalous impurity Auger line shapes can be expected. The theory is developed for degenerate $d$ states, for which we determine the conditi…
Optical experiments have been used to study bound magnetic polarons (BMP) in (Cd,Mn)S, (Cd,Mn)Se and (Cd,Mn)Te. This work is surveyed, and the theory of these complexes is discussed. BMP exhibit a remarkable, continuous transition from fluctuation dominated behavior at high temperatures, to a cooperative regime at low…
The magnetic structure of high purity single crystals of holmium has been studied by neutron diffraction techniques. Although the general characteristics of the magnetic structure have been found to agree with earlier measurements, some discrepancies have been resolved and new features have been observed. The magnetic…
Samples of the Sm-Fe system have been directly crystallized onto heated substrates by selectively thermalized sputtering. Films of the pure Sm-Fe system exhibit only the 1–2, 1–3, and 2–17 phases which correspond to the bulk system. But samples synthesized with certain third element additions of oxygen and titanium ex…
We report studies of high-field magnetization and thermomagnetic effects in rapidly quenched and heat treated alloys based on Fe-Pr and Fe-Nd. Coercivities up to ∼40 kOe and large energy products result from the precipitation of a finely dispersed crystalline phase. Studies of varying the alloy composition and heat tr…
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…