Time filter

Source Type

Bristol, United States

Hueting N.A.,University of Bristol | Engin E.,University of Bristol | Md Zain A.,University of Bristol | Heard P.J.,Interface Analysis Center | And 2 more authors.
Optics InfoBase Conference Papers | Year: 2012

A deep etched 1D Distributed Bragg Reflector cavity in GaN-AlN-Sapphire has been analytically modeled and simulated using 2D FDTD. A structure fabricated using a hybrid Electron Beam- Focused Ion Beam method was assessed using microphotoluminescence. © 2011 Optical Society of America. Source

Zhou Q.,University of Bristol | Zhou Q.,Cooperation Technology | Heard P.J.,Interface Analysis Center | Schwarzacher W.,University of Bristol
Journal of Applied Physics | Year: 2011

Large area patterned NiFeMo thin films possessing long-range order were fabricated by electrodeposition through a template consisting of a self-assembled close-packed monolayer of polystyrene nanospheres of diameter 390 nm. Unlike many methods, this process generates films possessing both two-dimensional in-plane periodicity and features of varying cross-section in the growth direction. As a consequence, the magnetic properties of the patterned NiFeMo films depend strongly on film thickness. Inhomogeneous magnetization reversal that can be explained by different regions having different effective in-plane coercivities was observed for films with thickness greater than the nanosphere radius, but not for films with lesser thickness. We also observed oscillations in the in-plane coercivity as a function of the film thickness with a period significantly different to that reported for NiFe and Co films prepared by a similar method [A. A. Zhukov, Appl. Phys. Lett. 88, 062511 (2006)]. © 2011 American Institute of Physics. Source

Hueting N.A.,University of Bristol | Pugh J.R.,University of Bristol | Engin E.,University of Bristol | Zain A.M.,University of Bristol | And 4 more authors.
International Conference on Transparent Optical Networks | Year: 2012

A deep etched 1D Distributed Bragg Reflector (DBR) cavity in GaN-AlN-Sapphire has been analytically modelled and simulated using 2D FDTD. A 3 rd-order DBR has also been modelled including dye loaded polymer layer which can be used for emission enhancement characterization. A structure fabricated using a hybrid Electron Beam-Focused Ion Beam method was assessed using micro-photoluminescence. © 2012 IEEE. Source

Vasiljevic N.,H H Wills Physics Laboratory | Wood M.,H H Wills Physics Laboratory | Heard P.J.,Interface Analysis Center | Schwarzacher W.,H H Wills Physics Laboratory
Journal of the Electrochemical Society | Year: 2010

We studied the effect of submillimolar quantities of specifically adsorbing anions on the surface roughness evolution of Cu films electrodeposited from acidic perchlorate electrolytes. Using scaling analysis, we found that the roughness evolution of the thin films galvanostatically deposited at constant overpotential in the presence of different anions is correlated with the anions' adsorption energy. The roughness of the Cu films deposited in perchlorate electrolyte and the ones with the addition of nonadsorbing and weakly adsorbing anions follow almost the same anomalous scaling behavior. However, in the presence of specifically adsorbing halides, the roughness significantly changes, exhibiting near-normal scaling. This change is illustrated by a decrease in the local growth exponent, Βloc, [Βloc (F-) > Βloc (Cl-) > Βloc (Br-)] with an increase in anion adsorption strength (F- < Cl- < Br-). The X-ray diffraction analysis showed the thickness-dependent change of the preferred microstructure orientation from {111} to {220} occurring at lower thicknesses in the presence of specifically adsorbing halides. Focused ion beam microstructure analysis also reveals columnar growth and larger grain size for films grown in the presence of specifically adsorbing halides. In this paper we show how the effects of specific adsorption on the mechanism of deposition and surface transport processes influence the changes in both roughness and microstructure evolution. © 2010 The Electrochemical Society. Source

Keatley A.C.,Interface Analysis Center | Keatley A.C.,Bristol Oxford Nuclear Research Center | Scott T.B.,Interface Analysis Center | Scott T.B.,Bristol Oxford Nuclear Research Center | And 5 more authors.
Journal of Environmental Radioactivity | Year: 2015

Minor element composition and rare earth element (REE) concentrations in nuclear materials are important as they are used within the field of nuclear forensics as an indicator of sample origin. However recent studies into uranium ores and uranium ore concentrates (UOCs) have shown significant elemental and isotopic heterogeneity from a single mine site such that some sites have shown higher variation within the mine site than that seen between multiple sites.The elemental composition of both uranium and gangue minerals within ore samples taken along a single mineral vein in South West England have been measured and reported here. The analysis of the samples was undertaken to determine the extent of the localised variation in key elements. Energy Dispersive X-ray spectroscopy (EDS) was used to analyse the gangue mineralogy and measure major element composition. Minor element composition and rare earth element (REE) concentrations were measured by Electron Probe Microanalysis (EPMA).The results confirm that a number of key elements, REE concentrations and patterns used for origin location do show significant variation within mine. Furthermore significant variation is also visible on a meter scale. In addition three separate uranium phases were identified within the vein which indicates multiple uranium mineralisation events. In light of these localised elemental variations it is recommended that representative sampling for an area is undertaken prior to establishing the REE pattern that may be used to identify the originating mine for an unknown ore sample and prior to investigating impact of ore processing on any arising REE patterns. © 2015 Elsevier Ltd. Source

Discover hidden collaborations