Search results for " Magnetic materials"
showing 10 items of 4666 documents
Mixed polymeric monolayers and Langmuir-Blodgett multilayers with functional low molecular weight guest compounds
2008
Abstract Mixed monolayers and Langmuir-Blodgett multilayers of functional low molecular weight guest compounds, especially nonlinear optical (NLO) dyes, within the matrix of an amphotropic spacer polymer have been prepared. The polymer matrix enabled the transfer of guest compounds not capable of self-organizing at the air-water interface by themselves. The structure of the LB multilayers and the transfer process were studied by small angle X-ray scattering and UV-visible spectroscopy. Good NLO coefficients were found in the mixed films.
The structure of high-performance polymer blends by small-angle neutron scattering
1997
Abstract Amorphous blends from a deuterated polyaryletherketone and a polyetherimide have been prepared and investigated by small-angle neutron scattering (SANS). The blends are combinatorial mixtures: the scattering quantity Φ1Φ2/S(q) is independant of the composition of the blends.
QENS from polymer aggregates in supercritical CO2
2000
Abstract We report QENS measurements from PS-b-PFOA aggregates in supercritical CO2. Line shapes are dominated by localized diffusive modes and segmental dynamics of the anchored, finite-length PFOA chains. For Q⩽0.6 A−1, we obtain effective diffusion coefficients of ≅0.8 10−6 cm2/s. At higher Q, a single component is not sufficient as shown by excess intensity on the flanks. For Q⩾1.5 A−1, the wings reflect contributions due to a distribution of faster, more localized chain modes.
Low-temperature specific heat of orientational glasses
1992
This review summarizes specific heat data measured at low temperatures (T<1 K) on orientational glasses. Three species of mixed molecular crystals exhibiting orientational disorder are considered, namely (KBr)1−x (KCN) x , (NaCN)1−x (KCN) x (Rb)1−x (NH4) x H2PO4. For intermediate concentrations of the anisotropic components, glass-like excitations have been observed. It is demonstrated that with respect to thermal properties, orientational disorder leads to the same “universal” behaviours than for structural disorder, i.e. a specific heat which varies below 1 K and for times 10−4 s–10 s as:C p(T,t)∞T 1×ln(t). The variation of the glass-like anomaly with compositional disorder is also discus…
Iron(II) Metallomesogens Exhibiting Coupled Spin State and Liquid Crystal Phase Transitions near Room Temperature
2008
Reaction of the ligand 2,2,2-tris(2-aza-3-((5-akloxy)(6-methyl)(2-pyridyl))prop-2-enyl)ethane (C n -tameMe) with Fe(X) 2 . sH 2 O salts afforded a series of spin crossover metallomesogens with general formula [Fe(C n -tame)](X) 2 . sH 2 O (s ≥ 0), with n = 6, 10, 12, 14, 16, 17, 18, or 20 and X =ClO 4 - or BF 4 -. Single crystal X-ray measurements have been performed on the [Fe(C 6 -tameMe)](ClO 4 ) 2 (C 6 -1) derivative at 100 K. The complex C 6 -1 crystallizes in the triclinic system and adopts the Pbca space group. The iron(II) ion is in a distorted octahedral environment shaped by three imine and three pyridine nitrogen atoms of the C n -tameMe ligand. The average Fe-N im and Fe-N py bo…
Supramolecular isomerism in spin crossover networks with aurophilic interactions
2004
Assembly of FeII, 3-cyanopyridine and [Au(CN)2]– affords, in one-pot reaction, three coordination polymers that represent a genuine example of supramolecular isomerism with strong influence in the spin crossover regime of the FeII ions. Real Cabezos, Jose Antonio, Jose.A.Real@uv.es
Combined thermal evaporated and solution processed organic light emitting diodes
2011
Abstract Highly efficient, partly solution processed phosphorescent red, green and white organic light emitting diodes with small molecular weight host materials are prepared from commercially available starting compounds. Starting from an evaporated reference device, layers are stepwise replaced by solution processed layers. Replacing the evaporated hole transport layer by a solution processed polymer interlayer does not affect the performance and allows spincoating of the emissive layer after annealing of the polymer. Devices with, next to the spincoated hole injection and transport layer, a solution processed emission layer show similar characteristics and efficiencies as the reference d…
Functional 3D Photonic Films from Polymer Beads
2007
This paper describes synthesis and properties of polymer opals with a special emphasis on functional opals. Polymer opals are formed from monodisperse polymer colloids by self-assembly. Their potential applications range from coloring pigments, 3D bicontinuous supports for catalysis to photonic materials. This latter application requires especially the controlled creation of defects and the incorporation of fluorescent materials. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient photovoltaic and electroluminescent perovskite devices.
2015
Planar diode structures employing hybrid organic–inorganic methylammonium lead iodide perovskites lead to multifunctional devices exhibiting both a high photovoltaic efficiency and good electroluminescence. The electroluminescence strongly improves at higher current density applied using a pulsed driving method.
Dielectric and plasmonic waveguides based on quantum dots embedded in polymers
2013
espanolEn este trabajo se propone una revision de la implementacion de guias de onda activas basadas en la dispersion de puntos cuanticos coloidales (QDs) en polimeros. Para ello, guias de onda planas fueron fabricadas embebiendo distintos tipos de nanoestructuras semiconductoras con emision en el visible e infrarrojo (CdS, CdTe, CdSe, PbS) en PMMA, encontrandose las condiciones optimas para el guiado de su fotoluminiscencia y sus propiedades de ganancia y atenuacion. Si varios tipos de puntos son dispersados en la misma capa se propagan varios colores, siendo posible obtener luz blanca con las proporciones adecuadas de rojo, verde y azul. Asimismo, el guiado puede ser mejorado si una cubie…