Nanostructured Thermoelectric Oxides for Energy Generation

With growing concern over the consumption of fossil fuels and resulting carbon emissions, technologies must be developed to generate energy by alternative, clean routes. In the automotive sector, for example, international directives mean that new vehicles must be more fuel efficient without increasing emissions. For a vehicle powered by a typical internal combustion engine, approximately 25% of the fuel energy is used for vehicle mobility with the rest being lost by waste heat. One possible way forward to reduce fuel consumption and generate extra power is Thermoelectric (TE) technology, involving the direct conversion of heat into electric power. This requires modules containing both n-type and p-type functional materials having good thermal-electric conversion, described in part by a high Seebeck coefficient. Many existing TE materials, including Bi2Te3 and PbTe, have modest operating temperatures (400-600K) and are toxic. In the last decade oxide thermoelectrics have emerged as promising TE candidates, particularly perovskite structure n-type and layer structured p-type materials. They have flexible structures (enabling various substitutions), high temperature stability and encouraging thermal properties. In addition the oxides are environmentally friendly.

The project will focus on perovskite structured n-type TE oxide materials and will be carried out in parallel with a project on p-type TE materials. The key to developing high performance materials is to reduce both thermal conductivity and electrical resistivity. This will be addressed by modifying the microstructure at the atomic level (nanostructuring). The project will involve ceramic preparation, determination of thermal and electrical transport behaviour, electron microscopy (SEM and TEM) and may involve single crystal growth. Structural integrity and mechanical properties are also important.