Materials Literature
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Optical spectra of tetrahedrally coordinated Ni2+ ions in ZnO were studied as a function of temperature in the range from 94 to 673 K. Integral intensities of the spin-allowed 3T1(3F) → 3T1(3P)dd transitions on Ni2+ were found to be independent of temperature, indicating temperature independent oscillator strengths an…
The effect of the introduction of the 1,4-piperidine and 1,4-piperazine fragments into the molecular structure of liquid crystals on the appearance of the mesophases and their physico-chemical properties is discussed and compared with that of other well-known molecular fragments.
The piezoelectric modulus d 33, electromechanical coupling factor k 33 and elastic compliance coefficients s 33 D and s 33 E of SbSBr are determined by admittance measurement on single crystals of 8.43 mm in length and 0.3 2 0.3 mm 2 in cross section. The d 33 has the highest value of 6 2 10 m 5 cgsesu near the Curie…
The melt infiltration method was used to fabricate a SiC‐mullite composite at high temperature. Mullite was successfully obtained from a SiO 2 and Al 2 O 3 powder mixture by melting above 1830°C in a BN crucible with a lid. When infiltrated into a porous SiC preform, the mullite significantly reacted with SiC to form…
Sn(II) acts as template in reaction with WO42− in formate buffer, inducing the formation of decanuclear [SnW9O33]10− and further linking them by six Sn(II) centers to give orange 26-nuclear stannotungstate [Sn8W18O66]8−. Crystalline [Na12(OH)4(H2O)28][Sn8W18O66]·18H2O (1) was isolated and structurally characterized.
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According to the characteristics of serpentine in such aspects as its chemical composition, crystal structure and chemical bond, the authors have divided the activated atom group in serpentine into five classes, i.e. unsaturated Si—O—Si,O—Si—O, OH—Mg—OH(O) ,OH -,and O—H—O. With these unsaturated chemical bonds, serpen…
Crystal structure and transport properties of γ-NaxCoO2 have been studied in the range of x=0.67-0.75. Single-phase samples were prepared by sintering mixture of raw materials, Na2CO3 (99.5%) and Co3O4 (99.9%). Na/Co composition ratio (x) was determined by inductively coupled plasma (ICP) analysis. The crystal structu…
Abstract Graphical networks are cast into structural equivalence classes, with special focus on ones related to two‐dimensional regular translationally symmetric nets (or lattices). A quasilocal defect in a regular net is defined as consisting of a finite subnet surrounded outside this region by an infinitely extended…
Two ethylene vinyl acetate (EVA) copolymers (12 and 20 wt% of vinyl acetate,VA, content) have been treated with low pressure RF plasmas from non-oxidizing gases (Ar, N2) and oxidizing gases (air, a mixture of 4N2: 6O2 (v/v), O2 and CO2). The formation of polar moieties on both EVAs was more noticeable by treatment wit…
The influence of the Al content on the phase transformations in Cu-Al-Ag alloys was studied by classical differential thermal analysis (DTA), optical microscopy (OM) and X-ray diffractometry (XRD). The results indicated that the increase in the Al content and the presence of Ag decrease the rate of the <FONT FACE=S…
Hydrolyzable functional silanes are used as silicone elastomer crosslinkers. The hydrolysis, triggered by air moisture, leads to crosslinking of linear polymer chains to three-dimensional networks. The properties of these elastomers depend on the silane structure. The influence of the structure has been studied for RS…
The complex permittivity of films of polyether ether ketone (PEEK) has been investigated over a wide range of frequency. There is no relaxation peak in the range of 1Hz to 10(5) Hz but in the low-frequency side (10-4 Hz) there is an evidence of a peak that also can be observed by thermally stimulated discharge current…
We have prepared and studied four binary systems by doping a nonmesogenic optically active compound, namely 6-methoxy-2',4"-dibenzoylerythromycin, in various mesogenic compounds, namely 4-(4'-n-alkoxybenzoyloxy)phenylazo-4"-isoamyloxybenzenes (C 8 , C 10 ) and 4-(4'-n-alkoxybenzoyloxy)benzylidine-4"-isoamyloxy aniline…
We investigate the thermotropic liquid crystal phases formed in a system of biaxial discotic mesogenic Gay-Berne particles with strong in-plane interactions when the attractive and repulsive biaxialities have the same or the opposite sign. We find that a biaxial nematic phase is obtained when the shape and well depth…
Simple tensile tests and tensile tests after high temperature exposure of carbon fiber reinforced carbon matrix (C/C) composites have been carried out at high temperature (1000-1400 °C) in air. Types of specimens were bare, notched bare and CVD-SiC coated C/C composites. The CVD-SiC coated C/C composites were mechanic…
Electron holography study on magnetic domain structures of nanocrystalline magnetic materials was overviewed mainly based on the experimental results recently obtained by the author and his colleagues. Electron holography system which was established by modifying a conventional analytical electron microscope, i.e., in…
Americanae nace como un proyecto conjunto que surge dentro de la Red Europea de Información y Documentación sobre América Latina (REDIAL), y que ha afrontado la Biblioteca de la Agencia Española de Cooperación Internacional para el Desarrollo (AECID). Esta nueva biblioteca virtual hace más accesibles los libros digita…
New supported polypyrrole nanocomposites have been prepared and studied in this work. Self-supported sheets of fibrous cerium(IV) hydrogenphosphate (CePf) were used as the inorganic matrix, since the fibrous morphology presented by this material makes molding possible, giving a desired shape to the final polypyrrole/C…
NaxCo2O4 powders were synthesized using the polymerized complex (PC) method and then the polycrystalline samples were prepared by the spark plasma sintering (SPS) method. The microstructure and thermoelectric properties of these samples were evaluated, and their differences due to the preparation process of the polycr…