Materials Literature
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Huge built-in electric fields have been predicted to exist in wurtzite III-V nitrides thin films and multilayers. Such fields originate from heterointerface discontinuities of the macroscopic bulk polarization of the nitrides. Here we discuss the background theory, the role of spontaneous polarization in this context,…
The solvation of Al and its hydrolyzed species in water clusters has been studied by means of ab initio molecular dynamics simulations. The hexa-hydrate aluminum ion formed a stable complex in the finite temperature cluster simulation of one aluminum ion and 16 waters. The average dipole moment of strongly polarized h…
An introduction to the Propp-Wilson method of coupling-from-the-past for the Ising model is presented. It enables one to obtain exact samples from the equilibrium spin distribution for ferromagnetic interactions. Both uniform and random quenched magnetic fields are included. The time to couple from the past and its st…
Mesoporous silica SBA-15 molecular sieve has been synthesized and incorporated with aluminum via three different postsynthesis procedures by reacting SBA-15 with AlCl 3 in dry ethanol (route 1), with aluminum isopropoxide in dry hexane (route 2) and with an aqueous solution of sodium aluminate (route 3) followed by ca…
Using a novel thin film polymerization technique, we have observed the phase separation, coalescence, and annihilation of liquid crystal textures during polymerization of wholly aromatic main-chain liquid crystalline polymer poly( p -oxybenzoate/2,6-oxynaphthoate) (P(OBA/ONA)). The polycondensation reaction was conduc…
A calcium carbonate (CaCO 3 ) sorbent synthesized in the presence of surface modifiers has recently been developed in this laboratory for the purpose of enhancing the reactivity toward SO 2 at high temperatures (800−1150 °C). The calcium carbonate particles are produced by precipitation from an aqueous suspension of c…
A new class of metal sandwich complexes of silver derived from silver(I) perchlorate and fluoranthene (L 1 ), benzo[ ghi ]perylene (L 2 ), [2,2]paracyclophane (L 3 ), and decacyclene (L 4 ) was prepared. The idea behind the use of polycyclic aromatic compounds as an alternative approach for construction of organometal…
We have performed voltage dependent imaging and spatially resolved spectroscopy on the (110) surface of Te doped GaAs single crystals with a low temperature scanning tunneling microscope (STM). A large fraction of the observed defects are identified as Te dopant atoms which can be observed down to the fifth subsurface…
We investigate the phase diagram of an extended Kondo lattice model for doped manganese oxides in the presence of strong but finite Hund's coupling and on-site Coulomb interaction. By means of the Schwinger-boson mean-field approach, it is found that, besides magnetic ordering, there will be non-uniform charge distrib…
We have used a low-temperature scanning tunneling microscope (STM) to study the surface of heavily doped semiconductor InAs crystals. The crystals are cleaved in situ along the (110) plane. Apart from atomically flat areas, we also observe two major types of atomic scale defects which can be identified as S dopant ato…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Although the increasing amount of unburned carbon in fly ash is known to impede the efficient use of ash in the cement industry, very little is known about the characteristics of the unburned carbon. Three different types of carbon particles have been identified microscopically: inertinite, isotropic coke, and anisotr…
Alignment of hexagonal mesoporous silica particles was achieved by a simple rubbing method used for the alignment of liquid crystals on a very thin polyimide film coated on a silica glass substrate. Mesoporous silica was synthesized through the hydrolysis of tetraethoxysilane under acidic conditions in the presence of…
Axis formation in Drosophila depends on correct patterning of the follicular epithelium and on signaling between the germ line and soma during oogenesis. We describe a method for identifying genes expressed in the follicle cells with potential roles in axis formation. Follicle cells are purified from whole ovaries by…
We examine the step dynamics in a 1+1 dimensional model of epitaxial growth based on the BCF-theory. The model takes analytically into account the diffusion of adatoms, an incorporation mechanism and an Ehrlich-Schwoebel barrier at step edges. We find that the formation of mounds with a stable slope is closely related…
Specific matrix elements of exchange and correlation kernels in time-dependent density-functional theory are computed. The knowledge of these matrix elements not only constraints approximate time-dependent functionals, but also allows to link different practical approaches to excited states, either based on density-fu…
We report the magnetoresistance measurements of a highly oriented La0.55Ho0.15Sr0.3MnOz film on LaAlO3 substrate. The film has a metal-insulator transition around 200 K and shows pronounced thermomagnetic history effect in its transport properties below 45 K at 7 Tesla. The irreversibility temperature shifts to lower…
Amorphous Ta2O5 thin films were formed by radio-frequency magnetron sputtering at the substrate temperature of 200 °C. The electrical properties of Ta2O5 thin films were investigated as a function of the film thickness. The dominant conduction mechanism transited from the electrode-limited conduction (Schottky emissio…
Molecular simulations of a liquid crystal confined in slab geometry with homeotropic anchoring have been carried out. The application of an orientational perturbation has been used to calculate the surface extrapolation length λ = K 33/W θ, where W θ is the surface anchoring coefficient and K 33 is the bend elastic co…
Thin films of Ag-added La2/3Ca1/3MnO3 exhibit enhancement of several desirable characteristics over the pristine counterparts. We find that the addition of Ag results in a pronounced increase in the insulator–metal transition temperature (Tp) and ferromagnetic transition temperature (Tc). There is also a remarkable im…