Materials Literature
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Magnetization and Mössbauer studies have been carried out on GdCo3B2 and DyCo3B2. These compounds are magnetically ordered with Curie temperatures of 56 and 21 K, respectively. The Co atoms are either nonmagnetic or carry a small moment in these compounds. The saturation moment of DyCo3B2 at 5 K is smaller than the Dy…
A setup is described to determine the flow alignment angle θ0 in nematic liquid crystals. Results for compounds with and without a strongly polar terminal cyano group indicate that the antiparallel dipole correlation associated with cyano groups has no influence on θ0. The influence of the occurence of a smectic-A pha…
The magnetic susceptibility of polycrystalline samples of Cs2CuCl4 has been measured over the temperature interval 1.1–30 K. A broad maximum in the data, centered around 2.6–2.7 K, is consistent with the existence of lower-dimensional antiferromagnetic interactions in this compound. The model used for fitting the data…
SmCo5, Sm2(Co,Fe,Zr)17, and (Sm+Ti)Fe amorphous films were deposited by rf sputtering onto water cooled substrates with an applied field, Hs, of 2.5 or 1.75 kOe in the plane of the substrates during the sputter deposition. All of these systems have been made so as to exhibit in-plane rectangular hysteresis loops when…
The behavior of the diffraction field of a Gaussian beam through an aperture depends on incidence conditions and aperture radius. The field spread in the Fraunhofer region varies with the curvature of the equiphase surface of the incident beam as well as the ratio of the aperture radius to the spot size. The divergenc…
A Mössbauer study of Fe3−xAlxO4 and Fe3−xGaxO4 has been undertaken. Measurements at low temperatures in magnetic fields enabled us to better separate the Fe(A) and Fe(B) subspectra and to determine the cation distribution on tetrahedral and octahedral sites. Whereas Al up to x=1.4 shows a strong preference for B sites…
Linear π diradicals are treated as a through-bond interaction of two radical centers. The ferromagnetic or antiferromagnetic electron coupling is examined by means of an analytic study of the interaction of two methylene groups (the radical centers) through a butadiene (the bridge). The interaction of each radical cen…
On sintered Nd-Fe-B permanent magnets, magnetic domain pattern changes in applied fields and at elevated temperatures were observed by the Kerr effect. Patterns on pole and side faces were recorded for different magnetization states in fields up to 17 kOe at 20 °C, and remanent patterns at temperatures up to TC. They…
Multiple-scattering theory is used to evaluate the effective dielectric function \ensuremath{\epsilon}(\ensuremath{\omega}) for disordered systems in which spherical inclusions are densely packed in a host medium. We compare the well-known quasicrystalline approximation (QCA) with Roth's effective-medium approximation…
Using high resolution transmission electron microscopy, morphological aspects of the polycrystalline silicon (polysilicon)-single crystal silicon interface have been correlated to the surface treatment used prior to polysilicon deposition, and to high-temperature annealing. Specimens which were chemically oxidized pri…
The origin of magnetic hardening has been examined in Fe-Nd-B magnets by correlating the magnetic properties with the microstructure and magnetic domain structure observed with electron microscopy. Hysteresis loops and susceptibility studies show a magnetic anomaly at around 140 K. Microstructure studies reveal the pr…
We demonstrate for the first time that Te87Ge8Sn5 films, which are amorphous as deposited, can be optically switched between the crystalline and amorphous states more than 106 times. The measured reflectivity changed from 40% to 60% and the transmission changed from 3% to 1.5%, respectively, between the amorphous and…
We have used both electron-induced soft x-ray emission and fast inelastic electron scattering to observe 1S core-level emission and absorption in graphite near threshold. Linear phonon coupling with partial relaxation is found to quantitatively explain the absorption linewidth, the emission broadening, and the unusual…
GdRh, a ferromagnetic intermetallic, is of interest as a working material for magnetic refrigeration. The requirements for such materials have been discussed by Barclay et al. and it is in this context that we analyze our data. Magnetic measurements of Buschow et al. have indicated TC =24 K while specific heat measure…
Abstract Die synthetisierten farbigen α‐Styrylpyrylium‐Salze 2, 4 und 6 werden größtenteils im kristallinen Zustand zu den farblosen Cyclobutanen 7, 8 und 9 photodimerisiert (inverse Photochromie), deren r‐ctt ‐Konfiguration nachgewiesen wird. Bestrahlung von 2h in Lösung erzeugt u. a. das unerwartete Bispyrylium‐Salz…
Cooperative effects during both alkali-Ca and Na-K migration under electron irradiation of glasses have been pointed out for the first time by analysis of experimental data in the framework of the thermodynamics of irreversible processes.
MnAlGe is a ferromagnet with a unique crystal structure including two-dimensional arrays of Mn atoms in it. In order to find the magnetic properties characteristic of this structure, magnetic and electric measurements were made for Mn0.9M0.1AlGe (M:Mn, Cr, Fe) and MnGaGe. It has been found that the susceptibility abov…
We have determined the frequency-dependent scrE\ensuremath{\rightarrow}\ensuremath{\perp}c\ensuremath{\rightarrow} dielectric function \ensuremath{\epsilon}(\ensuremath{\omega}) for the stage-1 graphite intercalation compounds ${\mathrm{KC}}_{8}$, ${\mathrm{LiC}}_{6}$, and ${\mathrm{KHgC}}_{4}$ in the range 0--40 eV,…
A Hall coefficient and an electrical conductivity of NbO 2 were measured just below the metal-insulator transition temperature. It is concluded that the conduction is mainly a band conduction of large polarons above 550 K with an energy gap decreasing to zero toward the transition. A reflectivity measurement was consi…
Silver-based high-reflectance coatings that can withstand the humid and polluted conditions common in the open air have been developed for astronomical telescope optics. The successful designs incorporate a silver reflective layer with a copper underlayer and a stack of dielectric overlayers. Prototypes have been depo…