Materials Literature
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A new type of cation-compensated ${\mathrm{Fe}}^{3+}$ (S=(5/2) center designated [${\mathrm{FeO}}_{4}$/M${]}_{\mathrm{\ensuremath{\beta}}}^{0}$, with M=Li and H, has been found to exist in synthetic iron-doped \ensuremath{\alpha}-quartz, through an X-band electron paramagnetic resonance study. The spin-Hamiltonian par…
Abstract This paper focuses on the problem of scale‐up of two‐phase (e.g., solid‐fluid) reactors. It outlines a class of such reactors which, for first‐order reactions, scale in the familiar single‐phase manner via an analog of the usual residence time distribution formula. The differences lie in the fact that the app…
The dielectric relaxation time τ of KH2PO4 and CsH2AsO4 was investigated in the ferroelectric phase through measurements of the complex dielectric constants in the frequency range between 103 Hz and 109 Hz. Anomalous increase in τ near the domain freezing temperature Tf , considered together with the relation between…
It has been proved that on approaching the line of (first-order or second order) transition between ordered phases a symmetry breaking necessarily occurs within a domain wall. The symmetry breaking in the cases under investigation takes place as a second-order phase transition. Calculations were performed for a reorde…
Structural investigations concerning colour centres in MoO3 are described. The structure of MoO3 is studied by electron diffraction and by X-ray diffraction (powder technique). The films are coloured thermally, optically (UV), and electrically. During the crystallization process, the dangling bonds tend to connect the…
Abstract Medical grade black braided silk suture and pure mulberry silk twisted yarn were grafted with methacrylic acid (MAA) using 60 Co gamma radiation. The effect of various synthesis conditions on the grafting was studied. The addition of methanol in water has a marked effect on the degree of grafting, maximum yie…
The elastic moduli of the entire vitreous range of the system ZnO–P2O5 that can be prepared by melting ZnO and P2O5 oxides in open crucibles have been measured by ultrasonic techniques. The bulk, shear, longitudinal, and Young’s moduli, and the Poisson’s ratio are found to be rather sensitive to the glass composition.…
We optimized the losses in iron-rich metallic glasses by surface crystallization and by annealing in a field perpendicular to the ribbon surface. Both methods lead to a weak perpendicular anisotropy and rotational magnetization processes. The origin of surface crystallization could be traced to the effects of oxygen d…
Two models have been proposed to explain the mechanical strength increase of abraded or indented soda–lime glasses upon aging, namely, crack tip blunting and the release of residual tensile stress near the crack tip. To clarify the mechanism, the time dependence of the strengthening of an abraded soda–lime glass was i…
An experimental procedure for the determination of temperature de pendence of thermal conductivity of foam insulations blown with condensable gases is presented. The procedure is used to investigate the effect of the blowing agent on thermal conductivity of a polyurethane system blown with CFC-11 or HCFC-123, at vario…
Abstract The spin‐lattice relaxation time T 1 and the NMR second moment M 2 of 1 H and 19 F nuclei were determined at various temperatures above 77 K for (NH 4 ) 3 [InF 6 ] and (NH 4 ) 3 [GaF 6 ] crystals. From the fact that small M 2 values observed for both nuclei from fairly low temperatures, it is concluded that t…
The composition of n- and p-type CdTe surfaces before and after chemical modification by Ru have been examined using X-ray photoelectron spectroscopy (XPS). While the chemically etched unmodified surfaces were found to be covered by a thin layer of oxide due to ambient oxidation of a Te layer, Ru-modified surfaces wer…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation, characterization, and low-temperature transition of (triazatetrabenzoporphyrinato)copper(I) iodide, a new porphyrinic conductor with local moments coupled to itinerant charge carriersKwangkyoung Liou, Michael Y. Ogawa, Timothy P. Newcomb, Guy Quirion, Moohee Lee…
Adequate adhesion between metals and polymers is primarily the result of chemical bonds in the boundary layer. This region, however, is subject to degradation by moisture. Three modes of deterioration are observed. The first is a largely reversible weakening effect in the polymer layer near the metal oxide surface. Th…
Analytical electron microscopes are well suited for producing energy spectroscopic diffraction (ESD) patterns. In particular, an ESD pattern recorded at an element-specific energy loss yields information about the position of impurity atoms within the unit cell of a crystal lattice. Any quantitative information can on…
Abstract Post‐curing of vinyl‐addition cured siloxane networks can take place due to the presence of excess silicon hydride. The reaction of these groups, which leads to increased crosslink density especially at elevated temperatures, can be retarded by treatment with ammonia gas or eliminated by exposure to ethylene…
A molecular-dynamics simulation of liquid Bi at 578 K using a system of 16 384 particles, supported by neutron-scattering measurements, shows that the side peaks of its dynamical structure factor S(Q\ensuremath{\omega}), attributed to the collective density excitations, are unobservable beyond wave vector Q=0.6 A${\r{…
Hydrogen-terminated silicon surfaces produced by etching in solutions of HF have been studied using photoelectron spectroscopy and LEED. They have been found to be remarkably free from contamination, locally ordered and electrically passivated. The hydrogen may be removed from the (100) surface by annealing in UHV at…
A mechanistic study of oxide deposition from silane and nitrous oxide between 495°C and 690°C was performed in a laminar flow, cool wall reactor. Results indicated the existence of two distinct chemical pathways. At high nitrous oxide concentrations, the deposition reaction is dominated by radical chain chemistry init…
Effect of nickel and nitrogen contents on stress corrosion cracking (SCC) of 22%Cr–3%Mo-base duplex stainless steel was investigated in simulated sour environments with respect to both the base metal and the heat-affected zone (HAZ) of welding. The threshold stress and the critical chloride concentration for SCC were…