BiFeO3 nanopowders with a size distribution around 20nm and optical absorption onset at 2eV have been synthesized using self-combustion. These particles were used to photodecolourise RhB under AM1.5 irradiation. XPS showed changes to the oxidation state of the Fe cations. Under AM 1.5 illumination at pH 2 RhB showed >95% decolourisation after 10minutes.

In this paper, efficacy of p-n junction p-CuO/n-ZnO composite is assessed as a potential photocatalyst by monitoring degradation of methylene blue (MB) in the presence of UV light. The p-n junction photocatalyst, p-CuO/n-ZnO, was prepared by ball milling of ZnO and CuO in water. The structural properties of p-CuO/n-ZnO composite were characterized by x-ray diffractometer and surface charge properties via zeta potential measurement. The degradation of MB in the presence of composite powder was monitored via UV-vis spectrometer. Various studies affecting the degradation rate of MB were conducted as a function of weight fraction of CuO in the composite and ball milling time. The highest degradation rate of MB was achieved in CuO (10 Wt.%)/ZnO for which high negative zeta potential was recorded. The MB degradation efficiency was found to decrease with the samples ball milled for time longer than 12 hours due to increased agglomeration of particles. The mechanisms that influence the photocatalytic activity of p-CuO/n-ZnO are discussed based on the p-n junction principle.

In this work TiO2/Si multilayer structures have been grown by sputtering. After rapid thermal annealing in pure inert gas or inert gas with oxygen atmosphere the multilayers have been investigated by high resolution transmission electron microscopy, μ-Raman and dynamic secondary ion mass spectrometry for their structure and anatase/rutile phase composition. It has been found that the photocatalytically more active anatase TiO2 is stabilized and that interdiffusion and chemical reaction processes were strongly hindered up to 1100°C annealing temperature in oxygen containing atmosphere. These findings are of particular importance since only at this high temperature simultaneous formation of embedded Si nanocrystallites can be achieved.

Thin films of molybdenum oxide have been deposited by reactive magnetron sputtering and characterised by photoelectron spectroscopy. Such films of MoOx are increasingly being used as electrode interfaces in both organic light emitting diodes and bulk heterojunction polymer-fullerene solar cells. Control of the Mo to oxygen stoichiometry has been gained by two methods of R.F magnetron sputtering. The first method is by controlling the proportion of oxygen in the sputtering chamber and the second is by controlling the level of surface oxidation of the sputter target prior to deposition, both methods have been used to control average film stoichiometry. In general the transition from metallic like film to oxide like film occurs at an oxygen chamber partial pressure of 15 %. UPS measurements show that such a transition, and resulting increase in the average oxidation state, leads to a shift in the Fermi level from 4.5eV to 5.2eV with respect to vacuum. The presence of specific oxidation states below +6 give rise to electronic structures that lie between the valence band edge and the Fermi level. For reduced samples +2 and +5 oxidation states peaks appear at binding energies of 0.4eV and 2.1eV respectively while a third peak at 1eV could be attributed to either the presence of +3 or +4 oxidation states.

Metal oxide (MO) films (ZnO and CuO) were synthesized by hydrothermal methods and treated with hydrogen and oxygen plasmas. From uv-visible transmittance spectra, we have found that the optical band gaps of MO films blue-shifted with hydrogen plasma treatment, but red-shifted with oxygen plasma treatment. By alternating the treatment sequence of hydrogen and oxygen plasmas, the MO optical band gap values can be reversibly tuned with the tunable ranges as wide as 80 and 550 meV for ZnO and CuO, respectively. The mechanism for reversible tuning of optical property is proposed based on the results of optical emission, X-ray diffraction, and scanning electron microscopy characterization. Compared to conventional metal ion doping and high temperature annealing methods, the use of low-temperature hydrogen and oxygen plasmas is more environmentally friendly.

This study reports the influence of electrical and mechanical stresses on indium zinc oxide (IZO) thin film transistors (TFTs).The deformation is introduced by mounting the samples on cylindrical structures of varying radii creating tensile or compressive strains. The mechanical stresses are parallel and perpendicular to the length of the channel layer. Results reveal that, when the stresses are parallel to the channel length, mobilities increase under tensile stresses and reduce under compressive stresses; while, the effect on sub-threshold is contrary to this. However no changes are observed for mobilities and sub-threshold swings when the stresses are perpendicular to the channel length. The TFTs exhibit stability under the electromechanical stressing with no device failure observed over prolonged stress times.