Materials Literature
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Abstract While the success of density functional theory (DFT) has led to its use in a wide variety of fields such as physics, chemistry, materials science and biochemistry, it has long been recognised that conventional methods are very inefficient for large complex systems, because the memory requirements scale as N 2…
We face the problem to determine the slope dependent current during the epitaxial growth process of a crystal surface. This current is proportional to delta=(p+) + (p-), where (p+/-) are the probabilities for an atom landing on a terrace to attach to the ascending (p+) or descending (p-) step. If the landing probabili…
The binary Fe-Cr alloy is a system with a miscibility gap. The decomposition occurs either via the nucleation and growth mechanism or as spinodal decomposition, depending on the Cr content. However, at low chromium concentrations the alloys are anomalously stable. This is shown to be true only for the ferromagnetic bo…
The synthesis and structural and magnetic characterization of an S = 6 cyanide-bridged octanuclear FeIII4NiII4 (1) complex is described. Ac susceptibility and mu-SQUID measurements suggest that fast magnetization relaxation is present in zero-field due to quantum tunneling of the ground spin state (QTM) while applicat…
Metallic iron nanoparticles were synthesized within micron-sized mesoporous molecular sieves (with 2.9-nm pores) and hollow silica microcapsules (pores of 2.7 and 15 nm) using several cycles of wet impregnation under vacuum, followed by drying, oxidation, and reduction steps. For iron-loaded MCM-48, SQUID measurements…
Abstract Vaterite mesocrystals with hexagonal morphology and uniform size have been successfully synthesized in the presence of a N ‐trimethylammonium derivative of hydroxyethyl cellulose via aggregation‐mediated crystallization using a simple gas‐diffusion method. The uniform hexagonal plates display sharp facets and…
We investigate theoretically the prospects of ferromagnetism being induced by cation vacancies in nonmagnetic oxides. A single Ca vacancy V(0)(Ca) has a magnetic moment due to its open-shell structure but the ferromagnetic interaction between two vacancies extends only to four neighbors or less. To achieve magnetic pe…
Zirconium diboride (ZrB 2 ) was densified (>98% relative density) at temperatures as low as 1850°C by pressureless sintering. Sintering was activated by removing oxide impurities (B 2 O 3 and ZrO 2 ) from particle surfaces. Boron oxide had a high vapor pressure and was removed during heating under a mild vacuum (∼1…
The self-assembly behavior of linear AB diblock copolymers has been studied extensively over the past three decades, from both experimental and theoretical perspectives.1-25 In the canonical theory, two independent parameters, the copolymer composition, f, and the degree of segregation, łN, govern the selection of the…
Polymer nanoparticles of 40-400 nm diameter with spiropyran-merocyanine dyes incorporated into their hydrophobic cavities have been prepared; in contrast to their virtually nonfluorescent character in most environments, the merocyanine forms of the encapsulated dyes are highly fluorescent. Spiro-mero photoisomerizatio…
When a liquid drop impinges a hydrophobic rough surface it can either bounce off the surface (fakir droplets) or be impaled and strongly stuck on it (Wenzel droplets). The analysis of drop impact and quasi-static “loading” experiments on model microfabricated surfaces allows to clearly identify the forces hindering th…
The effect of chemical non-stoichiometry and γ-irradiation on the unit cell parameters of ammonium tetrachlorozincate (NH4)2ZnCl4 (A2ZC4) has been studied. The unit cell parameters of crystal grown from solution with NH4Cl/ZnCl2 molar ratio 1:1, apparently non-stoichiometrric, are nearly the same as those given for am…
Continuum constitutive relations used in the design of macro-sized components assume that the elastic limit of a crystalline solid is time independent. Recent experiments using the nanoindentation technique, however, reveal that the elastic limit of submicron-sized metallic volumes decreases as time under load increas…
The thermomechanical response of an Ni–Ti–Cr shape-memory alloy is investigated at various initial temperatures, over a wide range of strain rates, using an Instron hydraulic testing machine and one of the modified split-Hopkinson-bar systems at the Center of Excellence for Advanced Materials, University of California…
Superlattices of [(La 0.7 Sr 0.3 MnO 3 ) 10 /(BaTiO 3 ) 4 ] 25 were grown on (001)-oriented SrTiO 3 using the pulsed laser deposition technique. The magnetic and transport properties were studied as a function of the oxygen pressure. The suppressed magnetism and associated transport properties are discussed. A high va…
Abstract Poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties (poly(HC‐MDI)) was prepared by polyaddition of 4,4′‐diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3‐hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six‐membered spiroorthocarbonate 1,5,7,11‐tetraoxa‐…
Abstract In this paper, a new type of organophilic montmorillonite, co‐treated with cetyltrimethyl ammonium bromide (CTAB) and 4,4′‐diphenymethylate diisocyanate (MDI), was modified and applied to prepare polyurethane/montmorillonite nanocomposites via in situ polymerization. The nanoscale montmorillonite layers were…
Abstract The H‐shaped copolymers, [poly( L ‐lactide)] 2 polystyrene [poly( L ‐lactide)] 2 , [(PLLA) 2 PSt(PLLA) 2 ] have been synthesized by combination of atom transfer radical polymerization (ATRP) with cationic ring‐opening polymerization (CROP). The first step of the synthesis is ATRP of St using α,α′‐dibromo‐ p ‐…
Potassium magnesium sulphate hexahydrate (picromerite) was synthesized and single crystals were obtained from saturated aqueous solution by slow evaporation method at room temperature. The crystals were bright, colourless and transparent having well defined external faces. The grown crystals were characterized through…
A PbTiO3 epitaxial thin film was deposited at 150°C at a thickness of 430nm. The domain structure was composed of c domain and small amount of a domain. The DE hysteresis curve and piezoelectric strain curve were asymmetrical because the initial domain structure was stable and difficult to reverse perfectly with an ex…