Materials Literature
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Shapes and energies of icosahedral fullerenes are studied on an atomically detailed level. The numerical results based on the effective binary carbon-carbon potential are related to the theory of elasticity of crystalline membranes with disclinations. Depending on fullerene size, three regimes are clearly identified,…
We consider pairing in a two-component atomic Fermi gas, in a three-dimensional optical lattice, when the components have unequal densities, i.e. the gas is polarized. We show that a superfluid where the translational symmetry is broken by a finite Cooper pair momentum, namely an FFLO-type state, minimizes the Helmhol…
The pressure behavior of the absorption edge of PbWO4 was studied up to 15.3 GPa. It red-shifts at -71 meV/GPa below 6.1 GPa, but at 6.3 GPa the band-gap collapses from 3.5 eV to 2.75 eV. From 6.3 GPa to 11.1 GPa, the absorption edge moves with a pressure coefficient of -98 meV/GPa, undergoing additional changes at 12…
Pairs of Au nanoparticles have recently been proposed as plasmon rulers based on the dependence of their light scattering on the interparticle distance. Preliminary work has suggested that plasmon rulers can be used to measure and monitor dynamic distance changes over the 1 to 100nm length scale in biology. Here, we s…
Using molecular dynamics, we investigate the crystal nucleation in a Lennard-Jones fluid as a function of the degree of supercooling. At moderate supercooling, a nucleation picture applies, while for deeper quenches, the phenomenon progressively acquires a spinodal character. We show that in the nucleation regime, the…
Plasmonic metal nanoparticles have great potential for chemical and biological sensor applications, due to their sensitive spectral response to the local environment of the nanoparticle surface and ease of monitoring the light signal due to their strong scattering or absorption. In this work, we investigated the depen…
The relationship between sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP) for all soils has traditionally been assumed to be similar to that developed by the United States Salinity Laboratory (USSL) in 1954. However, under certain conditions, this relationship has been shown not to be constant, b…
The pseudoelasticity of metastable Beta III titanium alloy (TMAtrade mark) used for orthodontic applications is obtained by cold wiredrawing. This wire has higher rigidity than cold-drawn NiTi (Nitinoltrade mark, superelastic NiTi SE) and lower recoverable deformation. The low ductility value of Beta III is due to the…
Thin LaMnO 3 + δ -layers were prepared by DC-magnetron sputtering. The structural, magnetic and electronic properties can be tailored by varying the preparation parameters. By reducing the oxygen excess δ within LaMnO 3 + δ , the lattice constant as well as the activation energy enlarges representing the semiconductin…
The determination of local strain fields at the surface of materials is of major importance for understanding their reactivity. In the present paper, lithography is used to fabricate grid points at the microscale and to map strain gradients within grains and between grains. This method was applied to duplex stainless…
The solid solubility of Ho 3+ in BaTiO 3 fired under the reducing conditions of a nitrogen atmosphere containing 10% of hydrogen was studied by quantitative electron‐probe microanalysis using wavelength‐dispersive spectroscopy. The solubility was found to depend mainly on the starting composition. In the TiO 2 ‐rich s…
Three in one: The oxidation of methane to methyl derivatives, conversion of the methyl derivatives into oxygenated compounds, and regeneration of the oxidation media are the three steps involved in the catalytic partial oxidation of methane by MoO2Br2 supported on Zn-MCM-48 (see scheme). Reversible bromine metathesis…
Schwämme nachgeahmt: Gut definierte kristalline Nanopartikel von kubischem BaTiO3 werden bei sehr niedriger Temperatur mit einem durch die Natur inspirierten Verfahren erhalten. Ein Dimetallalkoxid dient als alleinige Vorstufe in einer Dampfdiffusions-Sol-Gel-Synthese. Wasser und der Katalysator (HCl) werden mit einem…
We show that for arbitrary thermodynamic conditions, master curves of the entropy are obtained by expressing S(T, V) as a function of TV γ G , where T is temperature, V specific volume and γG the thermodynamic Grüneisen parameter. A similar scaling is known for structural relaxation times, τ = ℑ (TV γ); however, we fi…
We examine properties of a reaction front that forms in irreversible reaction-diffusion systems with concentration-dependent diffusivities. We study two different models of such systems and find that in the limit of a vanishingly small diffusivity of the reaction product, the reaction front dynamics enters a separate…
B 2 O 3 mineralizes spinel formation from stoichiometric (1:1 mole ratio) calcined magnesia and alumina. After 3 h at 1100°C, X‐ray diffraction (XRD) shows the mineralization effect of B 2 O 3 is limited to 1.5 wt% additions with higher B 2 O 3 contents leading to Mg 3 B 2 O 6 formation and reduced spinel content. Bor…
The synthesis of Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) with high‐energy milling was studied by X‐ray powder diffraction (XRD) using the Rietveld‐refinement method. The results are discussed in terms of the qualitative and quantitative composition of the crystalline and amorphous phases as a function of milling time. The mechano…
Going bananas: In a twisted geometry, an extrinsically chiral supermolecular structure was obtained in the calamitic phase. Upon cooling down to form the Bx phase, imbalanced growth of an intrinsic preferential chiral structure was attained. The preferential chiral handedness of the banana mesophase can be also contro…
Abstract In this work, the behavior of exothermic chemical reactions conducted in a wall‐cooled, semibatch stirred‐tank reactor is studied, with particular attention to conditions that lead to a thermal accident. The dimensionless heat and mass conservation equations for a semicontinuous tank were solved using second‐…
Ba 0.55 Sr 0.45 TiO 3 /MgO composites were successfully prepared by the heterogeneous precipitation method and their structural, surface morphological, tunable properties, and dielectric properties at microwave frequency were systemically investigated. Compared with the sample prepared by the traditional solid‐state m…