Nanosized thermoelectric materials The development of nanosized thermoelectric materials with enhanced properties is opening the way in the development of new terrestrial and space applications. Industrial Technologies © Corel Thermoelectric materials are semiconductors that combine heating and cooling properties. This makes them suitable for electrical energy generation and for cooling appliances. They do not require the use of carrier gasses for heating or cooling as other systems do, making them more widely applicable. The electrical properties of semiconductors change dramatically with temperature, and each material has its own effective operating range. A thermoelectric figure of merit. ZT, is also unique to each material, with higher ZT indicating better thermodynamic performance. The most commonly used semiconducting materials are alloys of Bismuth telluride, Bi-Te. A new chemical alloying method has been developed which allows such alloys to be made on a nanoscale. From a solution containing both components, Bi and Te, a precursor to the final product is precipitated. This consists of a solid solution of different intermediate compounds and is highly reactive. To achieve the alloying of the precursors, they are further treated at 350 degrees Celsius to produce the pure thermoelectric material with an excellent yield of 95-98% This process has also been used for the development of nanocrystalline skutterudites with a purity greater than 95%. The chemical alloying method developed is simpler than conventional melt processing. The alloys can be improved to provide nanocrystralline materials with increased ZT and TE properties and a lower manufacturing cost than is currently available. It is envisaged that this will result in the fabrication of thermoelectric devices for power generation, cooling and sensors to be used on land and in space. To this end, partners are invited to help develop the technology on an industrial scale and release end products based on the developed materials.
