Materials Literature
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We present a structural and magnetic study of La0.7Ca0.3MnO3 epitaxial films (the thickness ranges from 2.4 to 80 nm) on SrTiO3. Their structure, as obtained by x-ray diffraction, is orthorhombic with a 45° rotated 2×2 square lattice, referred to the SrTiO3 substrate, in the film plane. The 2.4 nm film adopts a differ…
The phase behavior of mixtures of polyisobutylene (PIB), polyethylene (PE), and a symmetric polyethylene- block -head-to-head polypropylene copolymer (PE−PP) was studied by transmission electron microscopy (TEM) and small-angle neutron and light scattering. The thermodynamic interactions between PE/PP and PE/PIB are r…
The low-field dielectric response of the relaxor-ferroelectric (1−x)PbFe2/3W1/3O3–xPbTiO3 ceramics with various x, was investigated. The permittivity data were analyzed with empirical laws that describe the diffuse phase transitions in relaxors. A change of the character of the phase transition was found with increasi…
A liquid crystal material of bent-core molecules is investigated by means of optical texture observations, x-ray measurements, and miscibility studies. While the x-ray and miscibility data point towards a B2 phase, the texture is however unusual, showing optical isotropy and segregation in two domains with opposite gy…
The thermal stability and dewetting effects of crystalline organic thin films on inorganic substrates have been investigated for a model system for organic epitaxy, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on Ag(111). The thin films deposited under a variety of growth conditions have been annealed stepwise…
In this paper, we report the magnetic and electrical properties of the Te-doped lanthanum manganite perovskite compound ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Te}}_{x}{\mathrm{MnO}}_{3}$ and the related electron spin resonance (ESR) study. This is a material with rhombohedral structure and it shows good colossal ma…
Single-crystal nanoparticles of silicon, several tens of nm in diameter, may be suitable as building blocks for single-nanoparticle electronic devices. Previous studies of nanoparticles produced in low-pressure plasmas have demonstrated the synthesis nanocrystals of 2–10 nm diameter but larger particles were amorphous…
The symmetry of magnetic quantum tunneling has been studied in the prototype single molecule magnet Mn12-acetate using a micro-Hall effect magnetometer and superconducting high field vector magnet system. An average crystal fourfold symmetry is shown to be due to local molecular environments of twofold symmetry that a…
Abstract Rigid polyurethane foams (PUFs) were prepared from polymeric 4,4′‐diphenylmethane diisocyanate (PMDI), polyether polyol, 1,4‐butanediol, silicone surfactant, and distilled water. The properties of the synthesized PUF samples were investigated with differential scanning calorimetry, scanning electron microscop…
The photoluminescence of rutile and anatase TiO2 has been investigated in the range of 360–890 nm at several temperatures. An unexpected intense near-infrared (1.53 eV) photoluminescence band was recorded for both phases. At low temperatures, the resulting bands form a substructure of equally spaced peaks irrespective…
The impact of 11 alloying elements, namely, Mg, Ti, In, Sn, Al, Ag, Co, Nb, and B, at two nominal concentrations of 1 and 3 at. %, and Ir and W, at only a nominal concentration of 3 at. %, on the resistivity and grain structure of copper was investigated. The films were electron beam evaporated onto thermally oxidized…
Using density functional theory (DFT) with gradient-corrected exchange-correlation functionals (B3LYP), we systematically study the electronic structure and bonding of oxygen to various Pt-clusters. Our aim is to understand how the cluster size and shape affect the chemistry of dispersed catalysts and to find the smal…
Oxidative photocurrents measured upon irradiation by a 7-W visible light (wavelength 312-700 nm) demonstrated that the sulfo-polyoxometalate anion clusters [S2W18O62]4- (1a), [S2Mo18O62]4- (1b), and [SMo12O40]2- (2) may be activated photochemically to oxidize the organic substrates benzyl alcohol, ethanol, and (-)-men…
Making derivatives of organic side chains on polyoxometalates is an important prerequisite for their application in biology. Compounds α1- and α2-[P2W17O61{Sn(CH2)2CO2H}]7− (depicted) were prepared for the first time and coupled with alcohols and amines, including C-protected amino acids.
Highly stable polarization gratings have been prepared in photocrosslinkable polymer liquid-crystal films by the use of two orthogonally polarized He–Cd laser beams and subsequent annealing. The resulting pure polarization gratings exhibiting thermal stability up to 150 °C diffract the beam and convert the polarizatio…
Photoluminescence (PL) properties of heavily P- and B-doped Si nanocrystals (nc-Si) are studied. By simultaneously doping two types of impurities, nc-Si exhibit strong PL at around 0.9 eV at room temperature. The temperature quenching of the PL is very small. Although the PL peak energy is very close to that of dangli…
We report the solution of the c(4 x 2) reconstruction of SrTiO(3) (001), obtained through a combination of high-resolution transmission electron microscopy, direct methods analysis, and density functional theory. The structure is characterized by a single overlayer of TiO(2) stoichiometry in which TiO(5) polyhedra are…
The electronic structure of PuO(2+/-x) was studied using first-principles quantum mechanics, realized with the self-interaction corrected local spin density method. In the stoichiometric PuO2 compound, Pu occurs in the Pu(IV) oxidation state, corresponding to a localized f4 shell. If oxygen is introduced onto the octa…
Aragonite thin films of calcium carbonate are selectively formed on crystalline poly(vinyl alcohol) matrices in the presence of poly(acrylic acid) in CaCO 3 solution. For thin film formation, this is the first example in which aragonite is formed selectively by cooperation of only synthetic organic macromolecules. In…
SWNTs are among the most attractive one-dimen-sional materials in the scientific world. Recently, con-siderable work has been done to modify SWNTs in order to bring these fascinating carbon structures into the fold of (macro)molecular chemistry and to endow SWNTs with ultimate new characteristics.1 The polymer wrap-pi…