Materials Literature
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Two different approaches to hysteresis modeling are compared using a common ground based on energy relations, defined in terms of dissipated and stored energy. Using the Preisach model and assuming that magnetization is mainly due to domain-wall motion, one can derive the expression of magnetization along a major loop…
La 0.7 Sr 0.3 Mn 1−x Ru x O 3 , 0⩽x⩽0.2 samples were prepared both in bulk and thin film formed using pulsed laser deposition. Magnetization measurements of bulk samples indicate a marginal decrease in Tc from 366 to 335 K up to 15% Ru substitution in Mn site. X-ray diffraction of the 〈100〉 oriented epitaxial films in…
The reactions of O(1D) atoms with fluorides have been investigated by time-resolved laser magnetic resonance (LMR). O(1D) atoms were produced by the dissociation of ozone with an excimer laser (KrF, 248 nm). By monitoring Cl atoms (when HCl or Cl2 is added) or FO radicals, the rate constants for total removal of O(1D)…
Quantitative texture analysis, which included calculation of the orientation distribution function, was used to demonstrate textures in hot‐pressed and subsequently annealed silicon carbide (SiC). The results indicated that the hot pressing and annealing could produce strong textures in SiC. Grain rotation during hot…
Two superstructures of the TTB type (tetragonal tungsten bronze) exist in the system Nb 2 O 5 /WO 3 . They are caused by an ordered arrangement of pentagonal tunnels filled with metal–oxygen strings. Besides the well known 4:9 phase (Nb 8 W 9 O 47 ), which has a tripled b axis, evidence for a new orthorhombic structur…
To understand the mechanism behind the pitch change during the transient planar to the planar state transition of a cholesteric liquid crystal (while it is relaxing from the homeotropic state to the planar state), we studied a more controlled situation of pitch change in a thermochromic liquid crystal. We studied the…
Oxiranes, such as glycidyl phenyl ether (GPE) and benzyl glycidate (BG), were copolymerized with succinic anhydride (SA) by lipase at a temperature between 60 and 80°C to yield the corresponding polyesters bearing carboxyl or phenyl groups. Bulk polymerization, especially at the temperature of 80°C, and preferably usi…
We report here the results of the synthesis of soluble polymers derived from 3,4- ethylenedioxythiophene. Starting from a 3,4-ethylene dioxythiophene monomer functionalized by an hydroxymethyl group, we synthesized several monomers bearing different side groups. The influence of alkyl chain length of side groups was s…
The synthesis and structural characterization of the novel [MnIII,IV2O2(N,Nbispicen)2](ClO4)3·CH3CN complex employing the tetradentate ligand N,Nbispicen = N,N-bis(2-pyridylmethyl)-1,2-diaminoethane are reported. Magnetic properties were determined and show that the ground state is a spin doublet. This can be quantita…
The effect of prepolymer structure on the electro-optic properties of polymer dispersed liquid crystals (PDLCs) prepared from UV-cured polyurethane acrylates (PUAs) has been studied. Among four types of films with different soft-segment structure, polypropylene glycol (PPG)- and polytetramethyl ether glycol (PTMG)-bas…
As an extension of the previous work on numerical analysis of electrical breakdown in polyethylene terephthalate films using electromechanical and thermal breakdown theories separately, an attempt is now made to combine these two models by introducing into the heat balance equation, variations in sample thickness whic…
The average depth of electron penetration is introduced as the physical quantity useful in electron beam irradiation. It is defined as the average of the maximum depths on the trajectories of electrons passing through finite, semi-infinite or infinite medium. The relation between the transmission coefficient as a func…
Abstract Mereheadite, ideally Pb 2 O(OH)Cl, is a new mineral related to litharge and which is structurally similar to synthetic bismuth-oxyhalides. With other lead- and lead-copper oxychlorides, it occupies lenses and cavities in veins of manganese and iron oxide minerals which cut through a sequence of dolomitic lime…
A time dependent permeation method is used to measure the permeability, diffusivity, and solubility of hydrogen in the low activation martensitic steel F82H, based on 7–10%Cr steel agedfor 2000 h under vacuum at 773 K. The measurements cover the temperature range 373–723 K which includes the onset of hydrogen trapping…
The coercivity of Sm2(Co,Fe,Cu,Zr)17 is calculated on the basis of a two dimensional model. To find local minima of the sum of the domain wall energy and the magnetostatic energy, the domain wall is divided into 1 nm long segments which are allowed to fluctuate randomly. With increasing field strength the domain wall…
High-resolution ac calorimetric measurements have been carried out for four chiral liquid-crystal systems: 4-(1-methylheptyloxycarbonyl) phenyl ${4}^{\ensuremath{'}}\ensuremath{-}\mathrm{o}\mathrm{c}\mathrm{t}\mathrm{y}\mathrm{l}\mathrm{o}\mathrm{x}\mathrm{y}\mathrm{b}\mathrm{i}\mathrm{p}\mathrm{h}\mathrm{e}\mathrm{n}…
Hematitas de nove solos e uma de itabirito foram tratadas com NaOH 5 mol L-1 e analisadas por difratometria de raios X (DRX), usando varredura escalonada (0,02°2θ/20 s). Determinaram-se o espaçamento d e as dimensões a0 e c0 da cela unitária. As amostras foram dissolvidas com ditionito-citrato-bicarbonato de sódio (DC…
/spl gamma/-radiation-induced absorption in the visible spectral region is studied in H/sub 2/-loaded and untreated optical fibers with high-OH low-Cl KU core and low-OH low-Cl KS-4V core. H/sub 2/-loading is found to suppress the low-dosage transient absorption band centered at 670 nm in KS-4V fibers. After irradiati…
Plates of high strength, low alloy (HSLA) steel (JIS‐G‐3115 SPV‐50Q) were found to be susceptible to sulfide stress cracking and hydrogen‐induced cracking (HIC) in wet H 2 S . The diffusion coefficient for the hydrogen atom in the SPV‐50Q steel was determined at 25–60°C and the activation energy for diffusion was 24.7…
Potassium (K) fixation plays a significant role in the soil‐plant system influencing the effectiveness of fertilizaiton. Among the factors controlling fixation capacity of soils, clay mineralogy and soil moisture are of primary importance. The objective of this experiment was to study the K fixation capacity of differ…