Materials Literature
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We develop a theory for nucleation on top of islands in epitaxial growth based on the derivation of lifetimes and rates governing individual microscopic processes. These processes are strongly affected by the additional step edge barrier E_S for descending atoms. If the dissociation times of unstable clusters can be n…
We report strong instantaneous photoinduced absorption (PA) in the quasi-one-dimensional Mott insulator ${\rm Sr_2CuO_3}$ in the IR spectral region. The observed PA is to an even-parity two-photon state that occurs immediately above the absorption edge. Theoretical calculations based on a two-band extended Hubbard mod…
We present a comparative numerical study of the ordered and the random two-dimensional sine-Gordon models on a lattice. We analytically compute the main features of the expected high temperature phase of both models, described by the Edwards-Wilkinson equation. We then use those results to locate the transition temper…
A considerable magnetic entropy change has been observed in Ni51.5Mn22.7Ga25.8 alloys under a field of 0.9 T. This change originates from a sharp magnetization jump which is associated with a martensitic to austenitic structure transition. The large low field entropy change and the adjustable martensic–austensic trans…
A first-principles-derived approach is developed to study finite-temperature properties of Pb(Zr1-xTix)O3 (PZT) solid solutions near the morphotropic phase boundary (MPB). Structural and piezoelectric predictions are in excellent agreement with experimental data and direct first-principles results. A low-temperature m…
High resolution x-ray powder diffraction measurements on poled PbZr1-xTixO3 (PZT) ceramic samples close to the rhombohedral-tetragonal phase boundary (the so-called morphotropic phase boundary) have shown that for both rhombohedral and tetragonal compositions the piezoelectric elongation of the unit cell does not occu…
Abstract This paper describes important features of an equation of state compositional simulator that are required for the simulation of the Vapex process:asphaltene precipitation andfluid mixing by molecular diffusion and convective dispersion. The asphaltene precipitate is modelled as a pure solid that may flow as a…
Cobalt(II) bis(3-fluorosalicylaldehyde)ethylenediamine (Co(fluomine)), an organometallic complex of known oxygen-binding capacity, has been synthesized in such a way as to anchor this material on the anion sites of selected nanoporous substrates. The O 2 - and N 2 -binding capacities of the resulting bulk materials we…
Multiferroic magnetoelectrics are materials that are both ferromagnetic and ferroelectric in the same phase. As a result, they have a spontaneous magnetization that can be switched by an applied magnetic field, a spontaneous polarization that can be switched by an applied electric field, and often some coupling betwee…
The continuing demand for higher frequency microprocessors and larger memory arrays has led to decreasing device dimensions and smaller process control windows. Decreasing process control windows have created a need for higher precision metrology to maintain an acceptable precision to tolerance ratio with a reasonable…
An unprecedented and remarkable redox transformation occurs in Rb2Bi4Se7 and Cs2Bi4Se7 in the solid state. The process involves the topotactic oxidative coupling of entire rows of Se2− ions to Se groups in a cooperative way reminiscent of the closing action of a zipper (see figure). This process happens over all the s…
Merocyanin-Farbstoffe mit einem großen Dipolmoment wie 1 aggregieren in Lösung zu Dimeren, in denen die Dipolmomente antiparallel orientiert sind. Durch Variation der Substituenten und die Untersuchung der lösungsmittelabhängigen Bindungseigenschaften wurde gezeigt, dass die Aggregation auf starke elektrostatische Dip…
The use of copper(I) halides as a preparative tool is discussed with respect to the synthesis of adduct compounds with new polymeric and oligomeric main group molecules. By using this approach new polymers of main group elements--some of which have been predicted by theoretical investigations--can be obtained in a cry…
Two very different complexes are isolated depending on whether the macrocycle L is assembled in the presence of a copper(I) template or whether a lead–macrocycle complex is subjected to transmetalation with copper(I). In the former case a tetracopper(I) grid complex is obtained, whereas in the latter the first example…
A specific two-dimensional tiling model, composed of the so-called Wang tiles has been studied at finite temperature using Monte Carlo numerical simulations. In the absence of any thermal bath the Wang tiles provide the opportunity of building a very large number of non-periodic tilings. We can construct a local Hamil…
We report here the first 77 Se nuclear magnetic resonance (NMR) and XRD study of the dynamical and structural behavior of selenate and selenite in hydrotalcite-like compounds (HT-SeO 4 and HT-SeO 3 ). The swelling properties and dynamical behavior of the anions in HT-SeO 4 and HT-SeO 3 are very different, and the resu…
The synthesis of liquid crystalline 3,4,5-tris(11-methacryloylundecyl-1-oxybenzyloxy)benzoic acid, 2-methyl-(1,4,7,10,13-pentaoxacyclopentadecane)-3,4,5-tris[4-(11-methacryloylundecyl-1-oxy)benzyloxy] benzoate and its 1:1 complex with sodium triflate is described. The observed mesophases were identified, by polarized…
New [3]- and [4]-dendralenes bearing electron-donor 1,3-dithiole and ferrocene substituents have been synthesised. Compounds 8, 15 and 17 have been characterised by single-crystal X-ray diffraction. Two of the dithiole rings of 8 are conjugated (dihedral angle 9 degrees), while the third dithiole ring is almost orthog…
Highly dipolar merocyanine dyes such as 1 form strong dimer aggregates with an antiparallel orientation of their dipole moments in solution. Substituent variations and solvent-dependent binding studies have shown that the aggregation is driven by electrostatic dipole–dipole interactions and that the dyes are prevented…
Chemical (vapors of formaldehyde), physical (temperature, UV and gamma radiation), and aging treatments were applied to wheat gluten films. Changes in film mechanical properties, water vapor permeability, solubility, and color coordinates were investigated. An aging of 360 h led to a 75 and 314% increase in tensile st…