Materials Literature
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Ester elimination between Sn(OBUt)4 and Sn(OAc)4 in refluxing toluene yields Sn6(O)6(OCMe3)6(O2CMe)6 which is characterized in solution and in the solid state by single-crystal X-ray diffraction; reaction of the same species in pyridine results in the formation of the ligand exchange products, Sn(OBut)X(OAc)4–x where…
Abstract We present results of computer simulations by the method of Brownian dynamics of polymeric brushes attached to impenetrable planes. For testing both model and method we have used one polymer brush attached to a repulsive plane and compare some results with Monte Carlo results of Lai and Binder on the bond flu…
The purpose of this study is a search for compositional ranges available to replace expensive heavy rare-earth elements (Gd, Dy) by a cheaper element such as Nd on keeping the heat resistance. The equilibrium phase diagrams of magnesium-rich portion of ternary alloys are made. Investigated compositional ranges are les…
Excellent transparent YAG ceramics, which contain Nd additives from 1.2 to 7.2 at%, were fabricated by the solid-state reaction method using high purity powders (>99.99 mass%) of Al2O3, Y2O3 and Nd2O3. The precipitated phase (Y1-δNdδAlO3) in accordance with increase in Nd content was clearly observed in Nd: YAG cerami…
Whiskers and powder of silicon nitride were prepared by the carbothermal reduction and nitridation of diatomaceous earth in the presence of flowing N 2 and NH 3 . The optimum temperature for the formation of Si 3 N 4 whiskers was 1350°C and the yield reached almost 20% after 24 h. The α‐Si 3 N 4 content decreased with…
With the aim of reducing surface cracks of continuously cast low carbon Nb containing steel, effects of morphology and composition of carbonitrides on high temperature ductility has been investigated under the condition which simulates thermal cycle of steel slab surface passing through spray cooling and bending zones…
A homogeneous coating fllm can be obtained on the mechanical alloying (MA) ball surface by ball milling of fine zirconia powder and Ti-34 mass%Al powder. X-ray diffraction pattern of MA powder containing 80 mass% zirconia is broad by MA for 360 ks under 35 kPa argon atmosphere. Fine zirconia powders combine a coating…
The surface oxides formed during water atomisation and sintering of austenitic stainless steel were determined using electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES). Optical microscopy and electron microscopy (SEM and TEM) were used for structural analysis of powder and sintere…
The sol–gel process opens the possibility of producing vitreous solids containing the main structural groups of oxide glasses and polymers by introducing compounds of the type RnSi(OR′)4–n into the starting mixture. The Si–C bond is normally stable towards hydrolysis and therefore the ligand R acts as a network modifi…
Ultrafine NiII-bearing ferrites (UNFs) with 14–100% Ni2+-substitution (x in NixFe3 –xO4) for Fe2+ in magnetite have been synthesized by hydrolysis of Ni2+, Fe2+ and Fe3+ ions at 60 °C, followed by aging of the co-precipitates at 60 °C and heating to 300 °C. The aged co-precipitates (ACPs) obtained at an NiII/Fetotal m…
Molecular dynamics simulation studies of the smectic B phase of the Gay–Berne model mesogen at constant volume suggest that the structure of the phase may be influenced by the periodic images. To avoid this problem we have undertaken an isothermal–isobaric Monte Carlo simulation of this phase. The ability of the dimen…
A new approach is proposed for analysis of scattering by a periodically corrugated dielectric layer with non-identical faces. The method combines the simultaneous use of several different coordinate systems and the generalized S-matrix formalism. The program has been tested by comparisons with results given by the int…
The sinterability and thermal conductivity of Y2O3 doped AlN powders with diverse specific surface areas (42-2.9m2g-1) and oxygen contents (0.2-2mass%) were evaluated. It was found that sintering of fine powders induces the densification at lower processing temperatures, and for raw AlN powders with specific surface a…
The changes in fibre structure caused by the realignment of the microfibrils of fibre and yarn samples treated with swelling agents, such as NaOH, LiOH, ZnCl2, and butyltrimethyl ammonium hydroxide (BTMAH), both under tension and slack, were studied by light and electron microscopy. The structural effects of treatment…
Calix[n]aryl esters 2n(n= 4 and 6) bearing two stable N–O·radicals on the lower rim are synthesized: in 26 the exchange interaction (El) changes in response to a metal-induced 1,2,3-alternate-to-cone conformational change but in 24 the metal-induced rotation of the carbonyl groups is not enough to change the El.
Abstract In basic solutions, the oxidised porphyrin 2 readily undergoes macrocyclic N ‐alkylation, with up to four bulky alkyl groups, including decyl and substituted benzyl moieties, being accomodated: an argument is presented to show that N ‐di‐alkylation occurs on opposite nitrogen atoms, on the same side of the ma…
Substitution of a NO + C3H8+ He flow by O2+ He at 623 K leads to the appearance on a H–Cu–ZSM-5 catalyst of three IR bands at 3366, 3290 and 3192 cm–1 assigned to NH3 species as confirmed by NH3 adsorption showing that ammonia is formed during the SCR of NO by propane in excess oxygen, suggesting that it could play th…
Mixtures of SiC powder with diamond seeds were subjected to hydrothermal treatment at 700–750 °C under pressures of 100–500 MPa. The results of this study demonstrate that well crystallised diamond is formed after hydrothermal treatment of SiC when diamond seeds are present.
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation H. Gramespacher, J. Meissner; Reversal of recovery direction during creep recovery of polymer ble…
The synthesis of solid-state materials generally requires high temperatures and long reaction times in order to overcome diffusion barriers and achieve homogeneous products. Recently chemical routes using reactive precursors have allowed for greater control over product characteristics including stoichiometry and crys…