Materials Literature
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A new pressureless hydrothermal method for the preparation of yttrium disilicate is presented. The obtained amorphous precursor was calcined at different temperatures to form the Y-, α-, β-, and γ-phases of Y 2 Si 2 O 7, which have been characterized by DTA, XRD, TEM, and 29 Si-MAS RMN and IR spectroscopy. It is shown…
The crystal structures of 35 molecular compounds have been redetermined from laboratory monochromatic capillary transmission X-ray powder diffraction data using the simulated-annealing approach embodied within the DASH structure solution package. The compounds represent industrially relevant areas (pharmaceuticals; me…
Covalent functionalization and pore size manipulation were successfully achieved on ordered mesoporous carbons, by using a method in which diazonium compounds were in-situ generated and reacted with the carbon surface. Aryl groups substituted on the 4-poisiton (Ar−R, R = chlorine, ester, and alkyl) were covalently att…
A new computer program is described, GRINSP (geometrically restrained inorganic structure prediction), which allows the exploration of the possibilities of occurrence of 3-, 4-, 5- and 6-connected three-dimensional networks. Hypothetical (as well as known structure) models for binary compounds are produced with exclus…
UV-vis absorption and resonance Raman spectra of the complexes fac-[Re(Cl)(CO)3(stpy)2] and fac-[Re(stpy)(CO)3(bpy)]+ (stpy = t-4-styrylpyridine, bpy = 2,2'-bipyridine) show that their lowest absorption bands are dominated by stpy-localized intraligand (IL) pi pi* transitions. For the latter complex a Re --> bpy trans…
Air-stable n-type carbon nanotube field-effect transistors (CNTFETs) were fabricated, with Si3N4 passivation films formed by catalytic chemical vapor deposition (Cat-CVD). Electrical measurements reveal that the p-type characteristics of CNTFETs are converted to n-type after fabricating Si3N4 passivation films at 270°…
Preferred orientation is immediately visible on synchrotron diffraction images as intensity variations along Debye rings. In this report, the Rietveld method is applied to obtain quantitative information about the orientation distribution from the analysis of a single synchrotron diffraction image. The method is illus…
A triethoxysilyl-terminated, six-armed poly(ϵ-caprolactone) porogen is synthesized and the terminal groups are found to significantly reduce the aggregation of the porogen molecules in an organosilicate precursor via their hybridization reaction with the precursor. The porogen molecules successfully imprint nanopores…
The reactions of surface functional groups have an important role in controlling conversion of char nitrogen to NOx during coal combustion. This study involved an investigation of the thermal stability and reactions of nitrogen surface functional groups in nanoporous carbons. Four suites of carbons, which were used as…
A new soft-step chemistry method has been developed to prepare pure cryptomelane-type manganese oxide materials (OMS-2) with the smallest particle sizes ever reported. The synthetic procedure is based on the reduction of KMnO 4 by H 2 O 2 under acidic conditions followed by reflux. An acetate-containing buffer solutio…
The water-soluble manganese(III) meso-tetrakis (N-ethylpyridinium-2-yl) porphyrin (Mn(III)TEPyP) and manganese(III) meso-(tetrakis(4-sulfonato-phenyl)) porphyrinate (Mn(III)TPPS) are able to chemically distinguish between HNO and NO donors, reacting with the former in a fast, efficient, and selective manner with conco…
Polymer/clay nanocomposite materials based on poly(propylene- graft -maleic anhydride) (PPgMAH) and two different organophilic modified clays were investigated by dielectric relaxation spectroscopy (DRS). In contrast to ungrafted polypropylene (PP), PPgMAH shows a dielectrically active relaxation process which can be…
Modulations in manganites attributed to stripes of charge/orbital/spin order are thought to result from strong electron-lattice interactions that lock the superlattice and parent lattice periodicities. Surprisingly in La1-xCaxMnO3 (x>0.5,90 K), convergent beam (3.6 nm spot) electron diffraction patterns rule out charg…
The crystal structure and growth mechanism of silver nanorods prepared by a seed-mediated surfactant method using the cationic surfactant cetyltrimethylammonium tosylate (CTAT) and its wormlike micelles are characterized by conventional and high-resolution transmission electron microscopy. Depending on the nanorod ori…
In this work we give the analysis of the low frequency dielectric response of selected kaolinitic clays at different water content ranging from dry, over plastic to liquid limit. For all samples investigated, depending on the moisture content, the real part of the dielectric function reflects the abnormal behaviour wi…
Abstract In semiconductor nanocrystals the electronic energy gap is determined not only by the material but also by the size of the nanocrystals. This allows the construction of an energy‐gap gradient normal to multiple layers of nanocrystals where the diameters of the nanocrystals are monotonically increasing or decr…
[reaction: see text] On the basis of an efficient Pd-catalyzed triarylation to a vinylsilane platform, four types of structurally well-defined triarylethene-based extended pi-systems have been prepared very rapidly. From a compound library constructed by the present method, it was possible to find a number of interest…
The vibrational spectrum of Mg(3)Al(2)Si(3)O(12) pyrope is calculated at the Gamma point by using the periodic ab initio CRYSTAL program that adopts an all-electron Gaussian-type basis set and the B3LYP Hamiltonian. The full set of frequencies (17 IR active, 25 RAMAN active, 55 silent modes) is calculated. The effect…
In situ high-pressure energy dispersive x-ray diffraction experiments on polycrystalline powder TiN with NaCl-type structure have been conducted with the pressure up to 30.1 GPa by using the diamond anvil cell instrument with synchrotron radiation at room tempearture. The experimental results suggested that an isostru…
We use Molecular Dynamics combined with Dissipative Particle Dynamics to construct a model of a binary mixture where the two species differ only in their dynamic properties (friction coefficients). For an asymmetric mixture of slow and fast particles we study the interdiffusion process. The relaxation of the compositi…