293 results found
Williams REA, Dixit M, Hauser A, et al., 2012, Comparative Study for Simulation of EELS Core Loss for Transition Metals in Double Perovskite Systems, Microscopy and Microanalysis, Vol: 18, Pages: 308-309, ISSN: 1431-9276
Goode AE, Perkins JM, Sandison A, et al., 2012, Chemical speciation of nanoparticles surrounding metal-on-metal hips, CHEMICAL COMMUNICATIONS, Vol: 48, Pages: 8335-8337, ISSN: 1359-7345
Liberti E, McGilvery CM, Menzel R, et al., 2012, Size effects in nanoscale dielectric materials, Conference on Electron-Microscopy-and-Analysis-Group (EMAG), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Gilchrist JB, Heutz S, McComb DW, 2012, Using TEM and XRD to probe crystal orientation in organic thin films grown with OMBD, Conference on Electron-Microscopy-and-Analysis-Group (EMAG), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Tariq F, Lee PD, Haswell R, et al., 2011, The influence of nanoscale microstructural variations on the pellet scale flow properties of hierarchical porous catalytic structures using multiscale 3D imaging, CHEMICAL ENGINEERING SCIENCE, Vol: 66, Pages: 5804-5812, ISSN: 0009-2509
Xie H-N, Larmour IA, Tileli V, et al., 2011, Deciphering Surface Enhanced Raman Scattering Activity of Gold Nanoworms through Optical Correlations, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 115, Pages: 20515-20522, ISSN: 1932-7447
Illy BN, Cruickshank AC, Da Campo R, et al., 2011, Electrodeposition of ultrathin ZnO buffer layers with controllable orientation for photovoltaic applications, ISSN: 0065-7727
ZnO is one of the most promising materials for applications in nanotechnology due to its large band gap and high electron mobility. A large amount of work has focused on the study of nanostructured ZnO. However, two dimensional transparent compact layers are also of great interest as transparent conductive oxides in optoelectronic devices. Compact ZnO layers are usually deposited by methods which are generally costly thus significantly limiting their potential application. Electrodeposition is a low cost alternative, offering a high degree of control on the characteristics. In this work the effects of the deposition parameters on the film characteristics have been studied in order to fabricate the thinnest electrodeposited films ever reported and to tune the crystallographic orientation. Incorporation of the layer into an organic ZnO/P3HT:PCBM solar cell is used to demonstrate how a careful control of the orientation can dramatically improve the photovoltaic device efficiency.
Illy BN, Cruickshank AC, Schumann S, et al., 2011, Electrodeposition of ZnO layers for photovoltaic applications: controlling film thickness and orientation, Journal of Materials Chemistry
Cruickshank A, Tay S, Illy B, et al., 2011, Electrodeposition of ZnO Nanostructures on Molecular Thin Films, Chemistry of Materials, Vol: 23, Pages: 3863-3870, ISSN: 1520-5002
Electrodeposition of highly crystalline ZnO nanostructures directly onto copper phthalocyanine and pentacene thin films, from aqueous solutions containing zinc nitrate and dissolved oxygen, has been successfully demonstrated for the first time using a two-step electrochemical deposition process. Importantly, surface activation of the molecular thin film substrates by depositing a thin layer of ZnO nanoparticles at high cathodic overpotentials prior to film growth was found to be crucial for achieving a dense coverage of ZnO nanostructures with uniform morphology. The mechanism for ZnO deposition via electroreduction of hydroxide precursor species (oxygen and NO3– ions) at the organic-electrolyte interface was shown to be analogous to that reported for conventional inorganic and metal electrodes. Comparison of cathodic current density-time curves, measured during deposition, with film orientation and morphology revealed that the cathodic current density and number of nucleation sites are key factors in determining the characteristics of ZnO film growth on organic substrates. Significantly, the CuPc and pentacene films are not damaged or degraded during this process.
McLachlan MA, Rahman H, Illy B, et al., 2011, Electrochemical deposition of ordered macroporous ZnO on transparent conducting electrodes, Materials Chemistry and Physics, Pages: 343-348
Large area macroporous zinc oxide (ZnO) films have been prepared by colloidal crystal templating on to transparent conducting oxide (TCO) substrates using an electrochemical deposition technique. Characterisation by scanning electron microscopy (SEM) reveals changes in the microstructure of the ZnO films as the template diameter and deposition potential are varied. Analysis by X-ray diffraction (XRD) and UV-Vis spectroscopy show that the structural variations do not influence the inherent properties of the ZnO. We attribute the observed microsturctural differences to variations in growth kinetics in response to the applied deposition potential and solution transport phenomena that are controlled by the template dimensions. The optical properties of the structures exhibit two distinct features, originating from the optical bandgap of the ZnO and the photonic band gap of the ordered macroporous structure.
Franklin JB, Zou B, Petrov P, et al., 2011, Optimised Pulsed Laser Deposition of ZnO Thin Films on Transparent Conducting Substrates, Journal of Materials Chemistry, Vol: 21, Pages: 8178-8182
The growth of polycrystalline zinc oxide (ZnO) thin films by pulsed laser deposition (PLD) on indium tin oxide (ITO) is reported. For the first time the influence of deposition temperature over an extended range (50 - 650 °C) is investigated on ITO. We describe the role of temperature on the optical and crystalline properties of the deposited films, of 120-250 nm thickness. Additionally, the effect of the background oxygen pressure is reported. Under all of the deposition conditions highly textured c-axis oriented ZnO, transparent (> 85%) and low roughness (RMS < 10 nm) films are formed. Growth temperatures ≥ 450 ˚C lead to the highest degree of crystallinity and film quality with measured full width half maximum (FWHM) of X-ray diffraction (XRD) peaks as small as 0.14 ˚2θ. XRD measurements of films grown at < 350 °C show a shift in the (002) diffraction peak to lower 2θ values, indicating that the deposited films are oxygen deficient. Increasing the oxygen pressure results in the preparation of stoichiometric films at temperatures as low as 50 °C. We demonstrate that in addition to forming high quality ZnO, the optical and electronic properties of ITO can be preserved, even at high temperature, presenting a methodology for preparing highly crystalline ZnO on ITO over a temperature window significantly larger than that of previous literature reports. Furthermore, the low temperature processing opens up the possibility of deposition on a wide range of substrates, especially those unsuitable for exposure to high temperatures.
Mclachlan MA, McComb DW, Ryan MP, et al., 2011, Probing local and global ferroelectric phase stability and polarization switching in ordered macroporous PZT, Advanced Functional Materials, Vol: 21, Pages: 941-947
We describe the characterization, ferroelectric phase stability and polarization switching in strain-free assemblies of PbZr0.3Ti0.7O3 (PZT) nanostructures. The 3-dimensionally ordered macroporous structures present uniquely large areas and volumes of PZT where the microstructure is spatially modulated and the composition is homogeneous. Variable temperature powder X-ray diffraction (XRD) studies show that the global structure is crystalline and tetragonal at room temperature and undergoes a reversible tetragonal to cubic phase transition on heating/cooling. The measured phase-transition temperature is 50 – 60 °C lower than bulk PZT of the same composition. The local ferroelectric properties were assessed using piezoresponse force spectroscopy that reveal an enhanced piezoresponse from the nanostructured films and demonstrate that the switching polarization can be spatially mapped across these structures. An enhanced piezoresponse is observed in the nanostructured films which we attribute to the formation of strain free films, thus for the first time we are able to assess the effects of crystallite-size independently of internal stress. Corresponding polarization distributions have been calculated for the bulk and nanostructured materials using a direct variational method and Landau-Ginzburg-Devonshire (LGD) theory. By correlating local and global characterisation techniques we have for the first time unambiguously demonstrated the formation of tetragonal and ferroelectric PZT in large volume nanostructured architectures. With the wide range of materials available that can be formed into such controlled architectures we conclude that this study opens a pathway for the effective studies of nanoscale ferroelectrics in uniquely large volumes
Tariq F, Haswell R, Lee PD, et al., 2011, Characterization of hierarchical pore structures in ceramics using multiscale tomography, ACTA MATERIALIA, Vol: 59, Pages: 2109-2120, ISSN: 1359-6454
Koh AL, Fernandez-Dominguez AI, McComb DW, et al., 2011, High-Resolution Mapping of Electron-Beam-Excited Plasmon Modes in Lithographically Defined Gold Nanostructures, NANO LETTERS, Vol: 11, Pages: 1323-1330, ISSN: 1530-6984
McGilvery CM, McComb DW, De Gendt S, et al., 2011, Characterization of Hafnia Powder Prepared from an Oxychloride Sol-Gel, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 94, Pages: 886-894, ISSN: 0002-7820
Coleman JN, Lotya M, O'Neill A, et al., 2011, Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials, SCIENCE, Vol: 331, Pages: 568-571, ISSN: 0036-8075
Cecchini MP, Stapountzi MA, McComb DW, et al., 2011, Flow-Based Autocorrelation Studies for the Detection and Investigation of Single-Particle Surface-Enhanced Resonance Raman Spectroscopic Events, Analytical Chemistry
Axelsson A-K, Aguesse F, Spillane L, et al., 2011, Quantitative strain analysis and growth mode of pulsed laser deposited epitaxial CoFe2O4 thin films, ACTA MATERIALIA, Vol: 59, Pages: 514-520, ISSN: 1359-6454
Schumann S, Campo RD, Illy B, et al., 2011, Inverted organic photovoltaic devices with high efficiency and stability based on metal oxide charge extraction layers, Journal of Materials Chemistry, 2011, Pages: 2381-2386
A substantial increase in device performance and operational stability in solution processed inverted bulk heterojunction (BHJ) organic photovoltaic devices (OPV) is demonstrated by introducing a zinc oxide (ZnO) interlayer between the electron collecting bottom electrode and the photoactive blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM). The structure and morphology of the dense, planar ZnO layers were controlled either by electro-deposition or spray pyrolysis techniques. Metal oxide sandwich OPV devices based on the photoactive blend on an electro-deposited ZnO interlayer with a (100) preferential crystal orientation, and using a tungsten oxide (WOx) interlayer on the opposite electrode, resulted in a remarkable increase in power conversion efficiency with a value of 4.91% under AM1.5 illumination and an external quantum efficiency of 74%. Electro-deposition of the ZnO at low temperature proved to be the most promising method for forming the ZnO interlayers, allowing the highest control of film structure and morphology, as well as leading to significantly improved device efficiency and stability.
Sonnefraud Y, Leen Koh A, McComb DW, et al., 2011, Nanoplasmonics: Engineering and observation of localized plasmon modes, Laser & Photonics Reviews, Pages: n/a-n/a, ISSN: 1863-8899
We report on the fabrication and characterization of a DNA nanopore detector with integrated tunneling electrodes. Functional tunneling devices were identified by tunneling spectroscopy in different solvents and then used in proof-of-principle experiments demonstrating, for the first time, concurrent tunneling detection and ionic current detection of DNA molecules in a nanopore platform. This is an important step toward ultrafast DNA sequencing by tunneling.
Koh AL, McComb DW, Maier SA, et al., 2010, Sub-10 nm patterning of gold nanostructures on silicon-nitride membranes for plasmon mapping with electron energy-loss spectroscopy, JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, Vol: 28, Pages: C6O45-C6O49, ISSN: 2166-2746
Perkins JM, Fearn S, Cook SN, et al., 2010, Anomalous Oxidation States in Multilayers for Fuel Cell Applications, ADVANCED FUNCTIONAL MATERIALS, Vol: 20, Pages: 2664-2674, ISSN: 1616-301X
Eustace DA, McComb DW, Craven AJ, 2010, Probing magnetic order in EELS of chromite spinels using both multiple scattering (FEFF8.2) and DFT (WIEN2k), MICRON, Vol: 41, Pages: 547-553, ISSN: 0968-4328
Jantou-Morris V, Horton MA, McComb DW, 2010, The nano-morphological relationships between apatite crystals and collagen fibrils in ivory dentine, BIOMATERIALS, Vol: 31, Pages: 5275-5286, ISSN: 0142-9612
Wang H, Mauthoor S, Din S, et al., 2010, Ultra long Copper Phthalocyanine Nanowires with New Crystal Structure and Broad Optical Absorption, ACS NANO, Vol: 4, Pages: 3921-3926, ISSN: 1936-0851
Clarke E, Howe P, Taylor M, et al., 2010, Persistent template effect in InAs/GaAs quantum dot bilayers, JOURNAL OF APPLIED PHYSICS, Vol: 107, ISSN: 0021-8979
Cavallaro A, Burriel M, Roqueta J, et al., 2010, Electronic nature of the enhanced conductivity in YSZ-STO multilayers deposited by PLD, SOLID STATE IONICS, Vol: 181, Pages: 592-601, ISSN: 0167-2738
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