Thermoelectric materials offer the unique capability to convert waste heat directly into electrical energy. Efficiency is related to a figure of merit (ZT = S2sT/k), that is determined by the Seebeck coefficient (S), electrical conductivity (s) and thermal conductivity (k). The inter-dependence of these three properties presents a formidable challenge in the design of high-performance materials. This project will focus on the creation of nano-particulate forms of thermoelectric material to achieve desirable reductions in thermal conductivity, while minimising the impact on electrical transport properties (S, s). The project will focus on mixed-anion systems, particularly chalco-halides, in which both sulphur and halide anions are present.
The project will entail development of top-down approaches to nanomaterials, in which bulk phases prepared by conventional high-temperature synthesis are subjected to high-energy ball milling or where mechanochemical synthesis from elemental components is achieved by ball milling. Complementary bottom-up approaches to nanoparticulate thermoelectrics, using solution-based methods will also be developed in an effort to effect greater control over the size, size distribution and morphology of the nanoparticles, to optimise these parameters to achieve the required reductions in thermal conductivity.
In addition to the synthetic program, the project will involve structural investigations using state-of-the-art X-ray methods, using both in-house equipment and that at the Diamond X-ray synchrotron facility, and neutron scattering at the ISIS facility, exploiting both diffraction and spectroscopic techniques. The nanostructures will be investigated using electron microscopy available through the University’s Chemical Analysis Facility. A comprehensive program of electrical- and thermal-transport property measurements will be conducted to evaluate the thermoelectric performance of materials. These data will inform the future synthetic strategy in an iterative manner.
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