Download Dopants in rare earth wolframate proton conductors Doping of

Project 1 Dopants in rare earth wolframate proton conductors Supervisors: Reidar Haugsrud and Anette Gunnæs Ceramic proton conductors are interesting materials for more efficient conversion of chemical energy to electrical energy than current conventional processes. Fuel cells and gas separation membranes are examples of this technology. However, before these technologies can be applied, materials with high enough proton conductivity and chemical and mechanical stability must be found. One group of materials with promising proton and mixed proton‐electron conductivity are the rare earth wolframates, Ln6WO12. These materials are often doped in order to enhance their properties, and your task in this project will be to determine if the dopant enters the material, and if so, how it affects the crystal structure. Project 2 Doping of the thermoelectric material ZnSb Supervisors: Øystein Prytz and Ole Bjørn Karlsen One component in the new energy landscape will be thermoelectric materials which can produce electricity from waste heat or act as efficient solid state refrigerators and heat‐
pumps. The technology based on thermoelectricity produces no harmful or greenhouse gas emission. The bottleneck with respect to the utilization of thermoelectricity is the thermoelectric material that needs be a good conductor of electricity and a poor conductor of heat. In addition, the material must produce a large voltage when exposed to a temperature gradient (the Seebeck coefficient). The thermoelectric material ZnSb is already promising for applications near room temperature, however, theoretical calculations indicate that a larger Seebeck coefficient can be achieved if the material is doped with for example Chromium or Manganese. Your task will be to determine if these dopants enter the material, characterize microstructure and composition variations, and investigate whether the dopants modify the crystal structure in any way. Project 3 Structure and composition of Ca­Co­O thin films Supervisor: Ola Nilsen Among the calcium cobalt oxides there are phases adopting one dimensional structure (Ca3Co2O6) and incommensurate structure (Ca2Co0.984O2.652) structure. In addition to these interesting structural properties, this system also displays very good high temperature thermoelectric properties and may therefore be of use for conversion of waste heat to electricity. This is therefore a very interesting type of material from both a fundamental perspective and with regards to its properties. Your task will be to identify and use analysis methods suitable to obtain information about: Elemental composition, the oxidation state of cobalt, crystal structure and the topography of the films. Project 4 Transparent conducting materials (TCO) Supervisor: Ola Nilsen Thin films of transparent conducting materials are relevant for next generation solar cells where the anti reflection coating acts both to increase the solar radiance towards the cell, but also as an active electrode. The ultimate goal is to replace the metallic conduction bands used today with a transparent material. The electrical conductivity of transparent materials is usually a result of doping in a transparent semiconducting material. It is of interest to understand the properties of the doped material in its host. The doped material may enter its host material in interstitial or substitutional positions. Samples of TCO materials are made in both bulk and thin film form. The tasks that should be undergone it to determine the elemental composition, crystalline structure, and possibly the oxidation state of the elements in the sample. It will also be beneficial if possible to provide information about the near order of the doped element in the sample and its distribution when made as thin film. Project 5 Characterization of nanoparticles in dental composites Supervisor: John Tibballs (NIOM) Dental composites consist of more than 70% inorganic powder bound to an organic resin which can be hardened using e.g. optical methods. Traditional composites have consisted of powders with average size 1‐1.5 μm, however, newer composites include silica particles with size down to 7 nm. These particles make the material smoother and more resistant to wear. However, materials that include nanoparticles need to be well characterized and analyzed for risk factors before being approved for medical use. Your task in this project is to analyze and characterize the silica nanoparticles both in their free form and as parts of a composite.