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46 items found (0 items not approved), displaying 41 to 46.[First/Prev] 1, 2, 3, 4, 5 [Next/Last]

Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	An EXAFS study on the photo-assisted growth of silver nanoparticles on titanium dioxide thin-films and the identification of their photochromic states Ivan P. Parkin , Claire J. Carmault , Stephen A. Parry , Andreas Kafizas , Alan V. Chadwick Physical Chemistry Chemical Physics DOI: 10.1039/c3cp44513e Diamond Proposal Number(s): [7134] Show Abstract ▼ Abstract: Anatase TiO2 thin-films were formed on glass by a sol–gel dip-coating method and annealed at 500 °C. Ag nanoparticles were grown on the surface of TiO2 by a photo-assisted process from AgNO3 salt using either UVC – 254 nm or UVA – 365 nm light. The size, shape and coverage of the particles were assessed by scanning electron microscopy. Changes in surface plasmon properties were investigated by UV-visible spectroscopy. A greater level of spherical Ag nanoparticles grew on TiO2 when using UVA light (365 nm); with particles 96 ± 33 nm wide on average and covering 29% of the surface. In the case of UVC light (254 nm), particles were 78 ± 14 nm wide on average and covered 13% of the surface. EXAFS measurements performed in situ of the Ag K-edge showed that the photo-assisted growth was more rapid when UVA light was used, leading to the full conversion of the AgNO3 salt layer in ≈1900 seconds. When UVC light was used, ≈50% of the salt layer was converted in ≈6100 seconds. The inhibited growth under UVC conditions was attributed to the absorption of light by the Ag nanoparticles as they formed (as opposed to the semiconductor beneath). The films also displayed reversible photochromism. The change in phase from the coloured (metallic Ag) to the bleached state (oxidized Ag) was identified using EXAFS spectroscopy. By comparing the EXAFS pattern with simulated model structures, it was shown that the transition from cubic Ag to cubic Ag2O was most likely, with an ≈70% conversion with 12 hours of white light irradiance. We believe that this is the first time the bleached form of silver in photochromic Ag–TiO2 thin-films has been identified by a direct method. In addition, we believe that this is the first case in which the photo-assisted formation of Ag–TiO2 has been monitored in situ under ambient temperature and pressure.	Apr 2013
I18-Microfocus Spectroscopy	Aerosol assisted chemical vapor deposition of transparent conductive zinc oxide films Davinder S. Bhachu , Gopinathan Sankar , Ivan P. Parkin Chemistry Of Materials 24 (24), 4704 - 4710 DOI: 10.1021/cm302913b Diamond Proposal Number(s): [8374] Show Abstract ▼ Abstract: Highly conductive and transparent ZnO films were synthesized by the reaction of diethyl zinc (in toluene) with methanol by dual source aerosol assisted chemical vapor deposition. These films displayed a stable sheet resistance of 7.2 Ω/□ and high transmission across the visible region comparable to commercial transparent conducting oxides (TCOs) based on oxides of tin or indium. Doping the zinc oxide structure with fluorine (trifluorotoluene) resulted in dense compact films with improved electrical properties than ZnO films with a sheet resistance of 4.5 Ω/□. These films also displayed idealized surface texturing for photovoltaic applications. Fluorine concentration was 2 at.% determined by wavelength dispersive X-ray analysis (WDX). Aluminum doped zinc oxide films were also synthesized by introducing dopant amounts of trimethylaluminium solution (in toluene) into the system. These films exhibited low sheet resistances of 14 Ω/□. The aluminum concentration in the films was 4 at.% determined by WDX.	Dec 2012
B18-Core EXAFS	Zeolite films: a new synthetic approach Davinder Bhachu , Andrew J. Smith , Ivan P. Parkin , Andrew J. Dent , Gopinathan Sankar Journal Of Materials Chemistry A DOI: 10.1039/c2ta00528j Show Abstract ▼ Abstract: Dense, adhesive zeolitic films were made for the first time by combining chemical vapour deposition (CVD) and hydrothermal methods. This new method uses a CVD process to deposit dense amorphous silica or titanium doped silica films which are then converted to a crystalline nanoporous zeolite by a hydrothermal process using an organic structure directing agent. To demonstrate the capability of the method, silicalite-1 (S-1) and titanium silicalite-1 (TS-1) zeolites were prepared. Both X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed the presence of crystalline zeolite films with well-defined morphology. Ti K-edge X-ray absorption spectroscopy (XAS) revealed the presence of the metal ions in the framework of the zeolitic matrix and in isolated, tetrahedral sites both in the amorphous and crystalline zeolite films. Both the pores and the titanium centres in the films were also shown to be accessible for molecules, by reacting with n-hexene and H2O2.	Dec 2012
B18-Core EXAFS	Superhydrophobic photocatalytic surfaces through direct incorporation of titania nanoparticles into a polymer M Colin R. Crick , Joseph C. Bear , Andreas Georgiou Kafizas , Ivan P. Parkin Advanced Materials 24 (26), 3505 - 3508 DOI: 10.1002/adma.201201239 PMID: 22706974 Diamond Proposal Number(s): [7134] Show Abstract ▼ Abstract: A new class of superhydrophobic photocatalytic surfaces that are self-cleaning through light-induced photodegradation and the Lotus effect are presented. The films are formed in a single-step aerosol-assisted chemical vapor deposition (AACVD) process. The films are durable and show no degradation on continuous exposure to UV-C radiation.	Jul 2012
I15-Extreme Conditions	High-pressure behavior and polymorphism of titanium oxynitride phase Ti2.85O4N Ashkan Salamat , Geoffrey Hyett , Raul Quesada Cabrera , Paul F. Mcmillan , Ivan P. Parkin Journal Of Physical Chemistry C 114 (18), 8546-8551 DOI: 10.1021/jp100769r Show Abstract ▼ Abstract: We report a crystallographic study of Ti2.85O4N, a new titanium oxynitride phase discovered using chemical vapor deposition and combinatorial chemistry techniques, under high-pressure conditions. Synchrotron X-ray diffraction was used to monitor structural changes in the material during compression up to 68 GPa. The data indicate that the orthorhombic (Cmcm) ambient-pressure phase (K0 = 154 ± 22 GPa with K0′ = 5.2 ± 0.5) undergoes a first-order transition at 18 GPa to a new orthorhombic (Pmc21) structure. This new high-pressure polymorph remains stable up to 42 GPa, after which the emergence of a second high-pressure monoclinic (P21/c) phase is observed.	Apr 2010
I11-High Resolution Powder Diffraction	High-throughput continuous hydrothermal synthesis of an entire nanoceramic phase diagram Xiaole Weng , Geoffrey Hyett , Martin Vickers , Paul Boldrin , Chiu C. Tang , Stephen P. Thompson , Jonathan Knowles , Ihtesham Rehman , Ivan Parkin , Julian R. G. Evans , Jawwad A. Darr , Jeremy K. Cockcroft , Julia E. Parker Journal Of Combinatorial Chemistry 11 (5), 829-834 DOI: 10.1021/cc900041a PMID: 19594110 Show Abstract ▼ Abstract: A novel High-Throughput Continuous Hydrothermal (HiTCH) flow synthesis reactor was used to make directly and rapidly a 66-sample nanoparticle library (entire phase diagram) of nanocrystalline Ce(x)Zr(y)Y(z)O(2-delta) in less than 12 h. High resolution PXRD data were obtained for the entire heat-treated library (at 1000 degrees C/I h) in less than a day using the new robotic beamline III, located at Diamond Light Source (DLS). This allowed Rietveld-quality powder X-ray diffraction (PXRD) data collection of the entire 66-sample library in <1 day. Consequently, the authors rapidly mapped Out phase behavior and sintering behaviors for the entire library. Out of the entire 66-sample heat-treated library, the PXRD data suggests that 43 possess the fluorite structure, of which 30 (out of 36) are tertiary compositions. The speed, quantity and quality of data obtained by our new approach, offers an exciting new development which will allow structure-property relationships to be accessed for nanoceramics in much shorter time periods.	Jul 2009

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