Materials Literature
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The FOCUS method, in which both crystal chemical information and powder diffraction data are included in the structure determination process, is presented. FOCUS combines automatic Fourier recycling with a specialized topology search specific to zeolites, which can be described as having three-dimensional four-connect…
In the iron(II) spin-crossover compound [Fe(ptz) 6 ](BF 4 ) 2, the thermal spin transition is accompanied by a crystallographic phase transition showing a hysteresis with T c ↓ = 128 K and T c ↑ = 135 K at ambient pressure [Franke, P. L.; Haasnot, J. G.; Zuur, A. P. Inorg. Chim. Acta 1982, 59, 5]. The hysteresis is du…
Three polymorphic modifications A-C of [Fe(II)(DPPA)(NCS)(2)], where DPPA = (3-aminopropyl)bis(2-pyridylmethyl)amine is a new tetradentate ligand, have been synthesized, and their structures, magnetic properties, and Mössbauer spectra have been investigated. For polymorph A, variable-temperature magnetic susceptibilit…
As part of a general study of the structure of spider silk fibers, major ampullate gland silk fibers were collected from Nephila clavipes spiders, and SAXS patterns were obtained from loops of fibers under a variety of conditions. Two orders of lamellar reflection were seen, with a long spacing of 8.4 nm. This increas…
The crystallization behavior of a series of ethylene- b -(3-methyl-1-butene) diblocks (E/MB) is investigated via simultaneous, time-resolved small-angle and wide-angle X-ray scattering. All the diblocks contain 26−27 wt % E, but possess varying molecular weights and hence varying segregation strengths in the melt, ran…
Hybrid inorganic−organic polymer composites have been prepared by a convergent approach in which nearly monodisperse CdSe or (CdSe)ZnS nanoclusters are sequestered within phosphine-containing domains in a charge-transporting matrix. The motivation for these studies is the potential utility of such composites as combin…
Reactive ion etching (RIE) of synthetic Ib diamond and chemical vapor deposition (CVD) diamond films in O 2 and CF 4 has been investigated. The large etch rate of up to 2.8 µ m/h and etch rate ratios of 15–20 for diamond (100)/Al were obtained at CF 4 /O 2 =10–20%. Numerous columnar structures of approximately 300 nm…
In vitro degradation studies of devices fabricated from polylactic acid (PLA) and polyglycolic acid (PGA) are usually performed at the physiologic 37°C and often take long periods of time to complete. The objective of the present study was to examine the degradation of a 50:50 PLA-PGA copolymer over a wide temperature…
Using a mixture of cetyltrimethylammonium bromide and carboxylate anionic surfactant (CnH2n+1COONa, n = 11, 13, 15, 17) as templates, siliceous MCM-48 is synthesized with low molar ratio (0.168:1) of mixed surfactants to silica and low concentration (5 wt %) of mixed surfactants.
In 2 O 3 exhibits a dramatic increase in solubility of SnO 2 and ZnO when they are cosubstituted into In 2 O 3 . The resultant material, In 2-2 x Sn x Zn x O 3-δ with x = 0−0.4, displays the same order of magnitude conductivity and transparency compared with bulk ITO (tin-doped indium oxide). Rapid quenching of In 2-2…
The two compounds CoCu(obbz)(H 2 O) 4 ·2H 2 O ( I ) and CoCu(obze)(H 2 O) 4 ·2H 2 O ( II ) have been synthesized, and their crystal structures have been determined at room temperature. Both compounds crystallize in the monoclinic system, space group P 2 1 / n . The lattice parameters are a = 7.8190(6) Å, b = 12.534(2)…
Among the many developments associated with sol−gel processing of particular relevance for information processing and optics applications is the preparation of photochromic sol−gel materials. If these materials are properly processed as thin films or attached to optical fibers, throughout the design of an adequate the…
The kinetics of the CO + NO and CO + O 2 reactions have been studied over several different Pd/Al 2 O 3 powder catalysts covering a wide range of average Pd particle sizes. The structure-insensitive nature of the CO + O 2 reaction over Pd has been exploited to determine the relative dispersions in several Pd/Al 2 O 3…
[ N, N ‘-Ethylenebis( o -( tert -butyl- p -methylsalicylaldiminato)]oxovanadium(IV) ( 1 ), [ N, N ‘-propanediylbis( o -( tert -butyl- p -methylsalicylaldiminato)]oxovanadium(IV) ( 2 ), bis( N -methylsalicylaldiminato)oxovanadium(IV) ( 3 ), bis( N -isopropyl- o -methylsalicylaldiminato)oxovanadium(IV) ( 4 ), and, bis(…
Low-energy phonons were studied in the ferromagnetic and paramagnetic phases of the Heusler alloy ${\mathrm{Ni}}_{2}\mathrm{MnGa}.$ The investigated sample shows a martensitic phase transformation with a transition temperature ${T}_{M}\ensuremath{\approx}284\mathrm{K},$ only about 80 K below the Curie temperature. The…
The emergence of the synchrotron radiation center in the past decade has resulted in a tremendous development of various techniques. XAS is an efficient tool for describing local organization in materials such as nanometer-scale metallic clusters but is insensitive to polydispersity. Ab initio calculations of the diff…
A mathematical model of a complete cell containing a porous intercalation electrode with two characteristic particle sizes is presented. Galvanostatic cycling and relaxation phenomena on open‐circuit are compared to a cell with a single particle size. Electrodes with a particle‐size distribution show modestly inferior…
Abstract The acidic properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples. Treatment of the minerals with different concentrations of hydrochloric acid results in the variation of…
Abstract The effects of exchanged cation and layer charge on the sorption of water and ethylene glycol monoethyl ether (EGME) vapors on montmorillonite have been studied on SAz-1 and SWy-1 source clays, each exchanged respectively with Ca, Na, K, Cs and tetramethylammonium (TMA) cations. The corresponding lattice expa…
[Cu(hyetrz) 3 ](ClO 4 ) 2 ·3H 2 O (hyetrz = 4-(2-hydroxyethyl)-1,2,4-triazole) represents the first structurally characterized metal(II) chain compound containing triple N 1, N 2 -1,2,4-triazole bridges. The structure has been solved at 298 K by single-crystal X-ray analysis. catena -Poly[μ-tris(4-(2-hydroxyethyl)-1,2…