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Incidence X-ray Diffraction (incidence + x-ray_diffraction)
Selected AbstractsAbrupt Morphology Change upon Thermal Annealing in Poly(3-Hexylthiophene)/Soluble Fullerene Blend Films for Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Minjung Shin Abstract The in situ morphology change upon thermal annealing in bulk heterojunction blend films of regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) is measured by a grazing incidence X-ray diffraction (GIXD) method using a synchrotron radiation source. The results show that the film morphology,including the size and population of P3HT crystallites,abruptly changes at 140,°C between 5 and 30,min and is then stable up to 120,min. This trend is almost in good agreement with the performance change of polymer solar cells fabricated under the same conditions. The certain morphology change after 5,min annealing at 140,°C is assigned to the on-going thermal transition of P3HT molecules in the presence of PCBM transition. Field-emission scanning electron microscopy measurements show that the crack-like surface of blend films becomes smaller after a very short annealing time, but does not change further with increasing annealing time. These findings indicate that the stability of P3HT:PCBM solar cells cannot be secured by short-time annealing owing to the unsettled morphology, even though the resulting efficiency is high. [source] Organic Thin Film Transistors with Polymer Brush Gate Dielectrics Synthesized by Atom Transfer Radical PolymerizationADVANCED FUNCTIONAL MATERIALS, Issue 1 2008C. Pinto Abstract Low operating voltage is an important requirement that must be met for industrial adoption of organic field-effect transistors (OFETs). We report here solution fabricated polymer brush gate insulators with good uniformity, low surface roughness and high capacitance. These ultra thin polymer films, synthesized by atom transfer radical polymerization (ATRP), were used to fabricate low voltage OFETs with both evaporated pentacene and solution deposited poly(3-hexylthiophene). The semiconductor-dielectric interfaces in these systems were studied with a variety of methods including scanning force microscopy, grazing incidence X-ray diffraction and neutron reflectometry. These studies highlighted key differences between the surfaces of brush and spun cast polymethyl methacrylate (PMMA) films. [source] Precise Structure of Pentacene Monolayers on Amorphous Silicon Oxide and Relation to Charge TransportADVANCED MATERIALS, Issue 22 2009Stefan C. B. Mannsfeld The precise molecular packing in pentacene monolayers on silicon oxide is determined for the first time using a combination of grazing incidence X-ray diffraction (GIXD) and crystallographic refinement calculations. The pentacene molecules are found to adopt a completely tilt-free herringbone motif, the charge-transport properties of which are discussed on the basis of density functional theory calculations. [source] Self-assembled structures of hydrophobins HFBI and HFBIIJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003Serimaa Ritva Hydrophobins are small proteins that function in the growth and development of fungi. The structures of class II hydrophobins HFBI and HFBII from Trichoderma reesei were studied using grazing incidence X-ray diffraction. HFBI was weakly ordered but HFBII formed a highly crystalline coating on water surface. Change from monoclinic to hexagonal structure was observed as the sample dried. The three-dimensional structures differed from the oblique two-dimensional structures observed in Langmuir-Blodgett monolayers of both HFBI and HFBII by atomic force microscopy. [source] Influence of Sn doping upon the phase change characteristics of Ge2Sb2Te5PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 14 2004K. Wang Abstract The influence of Sn doping upon the phase change characteristics of Ge2Sb2Te5 alloys has been investigated using four-point-probe electrical resistance measurements, grazing incidence X-ray diffraction (XRD), X-ray reflectometry (XRR) and variable incident angle spectroscopic ellipsometry (VASE), a static tester and atomic force microscopy (AFM). For a Ge2Sb2Te5 alloy doped with 4% Sn, two transition temperatures are observed in the temperature dependent sheet resistance measurements at 125 °C and 250 °C, respectively. The evolution of structures upon annealing, investigated by XRD, reveals that the first transition is caused by the crystallization of the amorphous film to a NaCl-type structure, while the second transition is related to the transition to a hexagonal structure. The density values of 6.02 ± 0.05 g cm,3, 6.38 ± 0.05 gcm,3 and 6.42 ± 0.05 gcm,3 are measured by XRR for the film in the amorphous, NaCl-type and hexagonal structure, respectively. Ultra-fast crystallization, which is correlated with a single NaCl-structure phase and the reduced activation barrier, is demonstrated. Sufficient optical contrast is exhibited and can be correlated with the density change upon crystallization. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic ArcPLASMA PROCESSES AND POLYMERS, Issue S1 2009Jose Luis Endrino Abstract The influence of annealing in argon at 300,°C on the conductivity, phase stability and electronic structure of hydrogen-free amorphous carbon (a-C) films containing copper (a-C:Cu) and gold (a-C:Au) nanoclusters was investigated. The motivation of this work is twofold: (1) to study the thermal stability of a-C:Cu and a-C:Au films and (2) to point out the relevance of X-ray absorption near edge structure (XANES) technique to study the structural evolution of metal-doped a-C nanocomposites. The films were produced at room temperature using a selective-bias pulsed dual-cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas grazing incidence X-ray diffraction (GIXRD) was used to monitor phase transformation and identify the dispersion or agglomeration of the crystallites within the carbon matrix. XANES spectra at the C-K was used to investigate the effect of annealing in argon on the electronic structure of the a-C matrix, while Cu K and Au L-edges were investigated on a-C:Cu and a-C:Au samples, respectively, to study the nanocluster evolution. XANES showed that the a-C host matrix increased its graphitic character and that stress was relieved upon annealing. No relevant changes were observed in the Au arrangements in a-C:Au films. In the case of the a-C:Cu samples, the Cu-K XANES spectra indicated the formation of Cu2O crystals which correlated well with GIXRD spectra and the decrease in conductivity. [source] MOCVD of YF3 and Y1,xErxF3 Thin Films from Precursors Synthesized In Situ,CHEMICAL VAPOR DEPOSITION, Issue 6-7 2005G. Condorelli Abstract RE(hfac)3 precursors (RE = Y, Er and Hhfac=1,1,1,5,5,5-hexafluoroacetylacetonate) have been obtained in-situ in a metal-organic (MO) CVD reactor by vapor-solid reaction between Hhfac and powders of suitable mixtures of RE2O3 oxides. YF3 and Y1,xErxF3 (x , 0.2) ultra-thin films have been deposited over glass substrates under Ar/O2 environments. Fourier-transform infrared (FTIR) in-situ measurements have been used to identify the nature of the precursor species in the gas phase, as well as to investigate decomposition mechanisms which accompany the film growth. Deposition involves the breakdown of the metal,ligand bond, thus leading to free Hhfac ligands and fluorinated ketones. Films have been characterized by energy dispersive X-ray (EDX) microanalysis, grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). [source] Rational Design of Ag/TiO2 Nanosystems by a Combined RF-Sputtering/Sol-Gel ApproachCHEMPHYSCHEM, Issue 18 2009Lidia Armelao Dr. Abstract The present work is devoted to the preparation of Ag/TiO2 nanosystems by an original synthetic strategy, based on the radio-frequency (RF) sputtering of silver particles on titania-based xerogels prepared by the sol,gel (SG) route. This approach takes advantage of the synergy between the microporous xerogel structure and the infiltration power characterizing RF-sputtering, whose combination enables the obtainment of a tailored dispersion of Ag-containing particles into the titania matrix. In addition, the system,s chemico-physical features can be tuned further through proper ex situ thermal treatments in air at 400 and 600,°C. The synthesized composites are extensively characterized by the joint use of complementary techniques, that is, X-ray photoelectron and X-ray excited Auger electron spectroscopies (XPS, XE-AES), secondary ion mass spectrometry (SIMS), glancing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE,SEM), transmission electron microscopy (TEM), electron diffraction (ED), high-angle annular dark field scanning TEM (HAADF,STEM), energy-filtered TEM (EF,TEM) and optical absorption spectroscopy. Finally, the photocatalytic performances of selected samples in the decomposition of the azo-dye Plasmocorinth B are preliminarily investigated. The obtained results highlight the possibility of tailoring the system characteristics over a broad range, directly influencing their eventual functional properties. [source] | |||||||||||||