Materials Literature
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The high-temperature coercivity of mechanically alloyed and subsequently annealed RCo5(R=Sm and Y) is studied. The annealed materials have the hexagonal CaCu5structure with 2:17 (or 1:7) regions as a minor phase. High-temperature magnetic measurements show that the coercivities of materials decrease with increasing te…
Abstract Refractory materials such as ceramics and refractory metals/alloys are widely used for structural applications in severe environments where more efficient use of energy is a prime need. Owing to properties such as high strength and refractoriness, low thermal expansion and electric conductivity these material…
Precursor effects of martensitic transformations in two well-known shape memory alloys, Ti50Ni48Fe2 and Ti50Pd34Fe16, were studied extensively by energy-filtered electron microscopy, including in-situ observations, and high-resolution electron microscopy. Energy-filtered dark-field images, where weak diffuse scatterin…
Understanding the evolution of the chemical environment and potential inside a disbonded region is essential to a quantitative risk assessment of corrosion and stress corrosion cracking of pipelines. A general reactive transport model is presented in this paper that enables calculation of the time evolution of chemist…
Heat treatment effects on the physical properties have been investigated for Sr 2 FeMoO 6 single crystals with double perovskite structure. We have evaluated the occupancy g of the Fe 3+ ion on one sublattice of the perovskite- B site by Rietveld refinement of the synchrotron-radiation X-ray powder patterns. Both the…
Interaction between two rigid molecules for three mesogenic compounds are calculated by atom-atom potential method taking into account Van der Walls' and electrostatic interactions. Stacking, in-plane and overall minimum energy configurations are studied and the most favourable arrangements for the dimers are found. T…
Y2O3 thin films were synthesized by chemical vapor deposition (CVD) using Y(acac)3.xH2O (Hacac= 2,4-pentanedione) as precursor. This work is focused on the x-ray photoelectron spectroscopy (XPS) characterization of an Y2O3 thin film deposited on glass substrate at 450 °C in N2+O2 atmosphere and subsequently annealed i…
The effect of shear stress and pressure drop rate on cell nucleation density during the foaming process has been studied using a foaming process simulator. The major part of this simulator is a test chamber that can be temperature controlled and pressurized with gas. Shear stress can be applied to the polymer melt thr…
Isobutylene was initiated using 5- tert -butyl-1,3-di(2-chloro-2-propyl)benzene/TiCl 4 in 60/40 hexane/methyl chloride: [IB] 0 = 1.0 M, [TiCl 4 ] = 0.12 or 0.24 M, [ t -Bu- m -DCC] = 0.0119 M, T = −(40−80) °C. Most polymerizations contained a Lewis base or other additive, i.e., 2,4-dimethylpyridine, 2,6-di- tert -buty…
Cobalt-ferrite nanoparticles of size 10 to 15 nm have been synthesized in water-in-oil microemulsions (i.e., reverse micelles). When the Co/sup 2+//Fe/sup 2+/ molar ratio in the precursor solution reaches 1:1 and above, the resultant oxides are identified as having the cobalt ferrite structure. By increasing the Co/su…
A new photosensitive chiral dopant based on cinnamic acid and isosorbide was synthesised. UV light action leads to E-Z photoisomerization of the dopant about C=C double bond of cinnamoyl fragment. Mixtures of the dopant with nematic and cholestric polymers were studied. It was shown, that planarly-oriented films of mi…
Abstract Benzoic acid was crystallized in a T‐mixer by mixing hydrochloric acid and an aqueous sodium benzoate solution. Crystallization kinetics were determined by population balance modeling and parameter estimation by nonlinear optimization. The evaluation of several models showed that the model has to be carefully…
Abstract Occurrence, chemistry, crystal growth, technical applications, structure and polytypism of xonotlite Ca 6 Si 6 O 17 (OH) 2 are reviewed. Atomic coordinates of the three simplest ordered polytypes in modified Gard notation: Ma 2 bc (space group P 2/ a , a = 17.032, b = 7.363, c = 7.012 Å, β = 90.36°), Ma 2 b 2…
XPS spectra of manganese dioxide (MnO2) powder are presented. The spectra were collected using monochromated Al Kα x-rays. Spectra include survey scan, the Mn 2p, 3p, and 3s regions, the O 1s region, and the Mn LMM Auger transitions.
Single crystal Ni/sub 48/Mn/sub 31/Ga/sub 21/ magnetic shape memory alloy exhibits giant 5% field-induced strain (MSM effect) due to redistribution of martensitic variants. Magnetization of this alloy was studied as a function of field and temperature. Austenite-to-martensite transition occurs at 299 K. At room temper…
The use of clusters as elemental building blocks can open routes toward the fabrication of a new class of nanostructured solids and devices. We report the synthesis of nanostructured films using supersonic cluster beam deposition. A new type of cluster source based on microplasma ablation has been developed. This allo…
The main spectroscopic properties (absorption, emission, decay times) of Pr3+-doped Ca4GdO(BO3)3 (GdCOB) have been determined for the three X, Y, Z polarizations. The Judd–Ofelt analysis, extended to anisotropic crystals, normalized and modified to take into account the influence of the 4f5d lowest energy level, has b…
D. Vorländer was the leading scientist in liquid crystal chemistry in the first half of the 20th century who discovered many of the building principles for liquid crystalline compounds. It was known that Vorländer also synthesized some compounds with a bent molecular shape. In this paper we show that one of these comp…
An investigation of the microstructures of four U–Nb alloys has been conducted. The nominal Nb contents are 5, 9, 13 and 18at.% (approximately 2, 4, 5.5 and 8 wt%). The self-accommodating twin structures have been characterized and considered in terms of the lattice parameters of the martensite phases as well as the t…
Nonequilibrium molecular dynamics (NEMD) simulations play a major role in characterizing the rheological properties of fluids undergoing shear flow. However, all previous studies of flows in molecular fluids either use an “atomic” thermostat which makes incorrect assumptions concerning the streaming velocity of atoms…