Materials Literature
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We study the two pseudo-cubic perovskite ruthenates and , by means of LSDA electronic structure calculations using the LMTO method for both the idealized cubic and the real orthorhombic structures. The LSDA calculations predict that both orthorhombic structures are ferromagnetic, with magnetic moments of 2.0 and respe…
A new hydrogenation catalyst is formed by thermolysis of the anionic carbonyl cluster [Ag3Ru10C2(CO)28Cl]2− anchored to the mesoporous silicate MCM-41. The cluster was isolated and characterized in MCM-41 both before and after thermal treatment. The picture on the right shows a model, based in particular on EXAFS anal…
We study the kinetic temperature and the localization of cesium atoms in a three dimensional quasiperiodic optical potential created by the interference of five or six laser beams. Bragg scattering experiments show evidence of a quasiperiodic order for the atomic density. Temperature measurements are consistent with t…
A film of well-oriented carbon nanotubes was produced by sublimation decomposition of silicon carbide at 1700 °C by using YAG laser heating in a transmission electron microscope (TEM). The processes of SiC decomposition and the formation of carbon nanotubes were observed successively by high-resolution electron micros…
Cathodoluminescence at 77 K was used to study the optical properties of ion-implanted and annealed natural type IIa diamonds. The substrates were implanted at room temperature with C12+, B11+, P3+, and As75+ -ions with energies of up to 350 keV and doses of up to 13×1013cm−2. After annealing at 1200 °C, the cathodolum…
The effect of Zr addition on the corrosion behavior of the Ni3Al alloy in an aerated 3.5% NaCl solution has been studied by means of electrochemical methods. The results showed that the corrosion potential of Ni3Al first tended to be noble and then became active with an increase in Zr content. The corrosion current de…
Filled and gum compounds of Isobutylene-Isoprene rubber were extruded through a laboratory extruder at various feeding rates, different temperatures and revolutions per minute. The extruded compounds were vulcanized up to their optimum cure times and the mechanical properties of the vulcanizates were determined. The p…
An overview will be given of some recent results of microstructural electron microscopy studies on martensitic systems. The precursor structure observed in a ternary Ni-Mn-Ti alloy and its correlation with the ensuing stacking sequence is presented. New types of materials of a well known alloy, in casu splat-cooled an…
Transmission electron microscopy and scanning force microscopy of negative-stained, carbon-coated replica and mica-adsorbed preparations of 200 microM poly r(A-U) and 50 microM ethidium bromide/200 microM poly r(A-U) have been employed to evaluate ethidium-induced changes in poly r(A-U) topology. Poly r(A-U) alone exh…
Temperature dependence of the magnon frequency was studied for cubic MnTe epilayers by the Raman scattering measurements. Experimental data are compared to the results of theoretical calculations performed within the framework of the Heisenberg model using Green's function formalism.
Rayleigh-Brillouin spectra near the α-INC-β phase transition of quartz were measured. Near the INC-phase, a plateau appears between the LA-mode and the Rayleigh line. In order to take account of the interaction between the continuum (two phonon scattering from the soft branch) and the discrete LA-mode, Fano's formula…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNitrosamine/2,3-Dichloro-5,6-dicyano- 1,4-benzoquinone (DDQ) Complexes and the Formation of Donor-Appended DDQ Chains in the Solid StateMelinda L. Greer and Silas C. BlackstockView Author Information Department of Chemistry The University of Alabama Tuscaloosa, Alabama…
The stress-induced martensitic transformation has been studied at different temperatures T>Ms. The application of a stress o on a shape memory alloy leads to the apparition of oriented variants of martensite in the direction of the stress. It causes the superelastic effect. Beyond a critical stress o,, variants grow u…
Abstract Nanostructured mesoporous silicates displaying hexagonally arranged channels, templated using a liquid crystal mesophase, were investigated using H‐2 and N‐15 NMR spectroscopy. It is shown that N‐15 MAS NMR spectroscopy allows to estimate the surface acidity of mesoporous materials by measuring the N‐H bond l…
The field of atomic and molecular photoionization has undoubtedly been transformed by the use of synchrotron radiation. In the mid-1960's the 180 MeV electron synchrotron at the National Bureau of Standards, Washington, DC, was used to discover many resonances in the photoionization continua of atoms and simple molecu…
We report on the specific heat, $C(T)$, measurements in the temperature ranges 4.5 K $<T<$ 30 K and 130 K $<T<$ 730 K of a one-dimensional carbon crystal phase synthesized by condensation of high-temperature carbon gas. Even at the lowest achieved temperatures, the measured $C(T)$ dependence, to the first…
The temperature induced transformation of single crystalline Ni -31.1% Mn -17.7% Ga (at%) shape memory alloy with Ms -446 K has been studied by means of dynamic mechanical analysis (DMA), calorimetry (DSC).dilatometq.three point bending tests and TEM.Two maxima in internal friction (IF) spectra on cooling and a single…
Based on the Pippard-Buckingham-Fairbank relation, a theory of critical ultrasonics near the isotropic-nematic transition in a liquid crystal is developed. This allows us to demonstrate that the attenuation data at different frequencies do indeed collapse on a single scaling plot in the isotropic phase.
Contamination of structures to be analyzed in an electron microscope is a severe problem for dimensional metrology applications, especially for low voltage electron microscopy. Two methods for contamination reduction which do not use a temperature variation of the sample or its environment have been investigated in th…
Abstract The monomer unit triad sequence distribution and the cis/trans linkage configurations at the cyclic maleic anhydride (MA) units in the copolymers of styrene (ST) and MA prepared in CCl 4 with AIBN at 50°C were quantitatively determined by 13 C DEPT NMR spectroscopy. So much as 61 % of the linkages at the MA u…