Materials Literature
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The structural aspects of xCs2O-(1-x)B2O3 glasses have been investigated by molecular dynamics as functions of Cs2O content (x=0.2, 0.3, and 0.4) and temperature (T=300 and 1250 K). The tetrahedral (BØ4-) and triangular (BØ3,BØ2O-, and BØO2 (2-)) short-range order borate units were found to be the structure-building e…
A preparação de complexos bentonita-ionenos a partir da adsorção de tetrametil-[x,y]-ionenos, onde x= 2 e y= 4,6,10 ou 12, e o 2-hidróxi-3-cloro-ioneno, EPI-DMA, foi realizada com a finalidade de observar o comportamento do tamanho do espaçador do ioneno na expansão basal (d001) das camadas de uma bentonita comercial…
The growth of science and technology of polyurethanes leads to the development of new materials with more desirable properties. Such kinds of materials include metal‐containing polyurethanes, poly(urethane‐urea)s, poly(urethane‐ether)s, poly(urethane‐ester)s, poly(urethane‐ether‐ester)s, poly(urethane‐imide)s, and pol…
Abstract A direct approach for producing methanol from methane in a three‐step, liquid phase process is reported. In the first step, methane is reacted with SO 3 to form methanesulfonic acid (MSA) at 75 °C using a free‐radical initiator and MSA as the solvent. Urea‐H 2 O 2 in combination with RhCl 3 is found to be the…
Vertically aligned carbon nanotubes (CNTs) with long length and high density were successfully synthesized on SiO2, Ta, and Ti substrates by thermal chemical vapor deposition (CVD). The use of Fe catalyst film supported by an Al buffer layer (Fe∕Al) has a significant influence on the increase of the number density of…
First-and second-order Raman scattering spectra in Si nanocrystals have been studied. The shift to lower frequencies and the substantial broadening of first-order Raman scattering lines observed to occur with decreasing nanoparticle size were established to correlate with those in second-order spectra. It is shown tha…
FCC metals with different stacking fault energy (SFE), namely Al, Cu and Ag have been investigated for the evolution of crystallographic texture during ECAE deformation using Route A. Different materials with different SFE result in their characteristic textures. The results have been analysed on the basis of microstr…
Copper of 4N purity was deformed at room temperature by equal channel angular pressing (ECAP) using three passes of route A. The local microstructure and texture were investigated by orientation imaging microscopy and high-energy synchrotron radiation, respectively. The microstructure consists of elongated grains whic…
Stoichiometric In 2 Se 3 films were deposited at room temperature. X-ray diffractometry (XRD) and field-emission scanning electron microscopy (FE-SEM) showed that the as-deposited films were amorphous and had very smooth surface morphology while the films annealed at 250°C or higher temperatures were crystalline and h…
The inhibition efficiency (IE) of adipic acid (AA)-Zn 2+ system in controlling corrosion of carbon steel immersed in well water has been evaluated by weight-loss method. The formulation consisting of 50 ppm of AA and 50 ppm of Zn 2+ has 95% IE. At lower pH value(pH=6) IE decreases and in alkaline medium (pH=8) IE incr…
Abstract This paper reviews the different types of heat resistant elastomers and the effects of compounding on the high temperature performance of these materials. Degradation mechanisms and testing procedures are discussed briefly. New developments in improving high temperature resistance are presented.
The adherence ability of cement clinker on magnesia–spinel refractories is investigated, using a sandwich test, at 1550°C for 30 min under a load of 5.3 kPa. Fractional factorial experiments determine that the silica ratio (SR)—SiO 2 /(Al 2 O 3 +Fe 2 O 3 ) and particle size of raw meal, as well as heating rate, have a…
Er-doped Ba0.7Sr0.3TiO3 (BST:Er) thin films prepared by the sol–gel technique have been investigated by means of x-ray diffraction (XRD), Raman, spectroscopic ellipsometry, Capacitance–voltage, and photoluminescence (PL) measurements. XRD results indicate that the film possess the highest degree of crystallinity at th…
Nanocrystallinity is an important phenomenon in natural and synthetic systems. Whether an inorganic or organic material, the mechanism for confinement of crystal growth within nanoscopic dimensions usually employs an organic mediator, which adsorbs to and stabilizes the growing crystal. Following an introduction to na…
A discussion is presented of nano-scale ferroelectric devices. Nano-ribbons exhibit an “extra” relaxation process with an 0.20 ± 0.01 eV activation energy attributed to OH hydroxyl ion reorientation. Barium titanate single crystals down to 65-nm are characterized by bulk properties, and broadening of dielectric peaks…
Abstract Biopolymers have the potential for use as a matrix for applications such as controlled release devices, environmentally sensitive membranes, mimic materials and energetic applications. Renewable resources (such as starch) can be utilized as polymer matrices for electroactive materials that are sensitive to th…
Photo‐oxidation of syndiotactic polypropylene–sPP/organoclay nanocomposites was performed. Nanocomposites were prepared in situ by melt compounding of sPP, compatibilizer (iPP grafted with maleic anhydride–iPP‐g‐MAN) and organoclay filler ME C18 (modified with octadecyl ammonium chains in intergaleries of layered sili…
Abstract Silica-supported Rh catalysts with different Rh particle dimensions were investigated for CO hydrogenation. The catalysts were characterized by various techniques such as TEM, H 2 -TPR and N 2 adsorption to study the catalyst morphology, the size distributions of Rh particles and the silica pores. It was foun…
ASTRACT Dislocations are the most common type of secondary defects and are unavoidaly present in all crystalline materials. They have een oserved in ferroelectric materials as in many other materials systems. Experiments have shown that they may have a significant impact on the degradation of the electrical properties…
Time decay of photoluminescence due to interstitial oxygen molecules (O2) in synthetic amorphous SiO2(a-SiO2) was studied by varying the fictive temperature and the concentrations of common dopants (SiOH, SiCl, and SiF groups). The decay constant is insensitive to the fictive temperature, but strongly depends on the t…