Investigation of Zintl Compounds for Thermoelectric and Magnetic Applications

University Of California-Davis, Davis CA

Investigators

Abstract

Technical Abstract: Devices made from thermoelectric materials are environmentally benign power sources that provide a significant solution to todays energy problems. These devices convert thermal energy directly into electrical energy, require little-to-no fuel, minimal maintenance and can be segmented to operate over a large temperature range (300 1275 K). Zintl phases meet many of the requirements for thermoelectric materials. The properties that lead to optimal thermoelectric devices are high Seebeck coefficient, low electrical resistivity and low thermal conductivity. This project will identify materials as possible good thermoelectric materials which are are small band-gap, semiconducting compounds that can be doped to enhance or to reduce the conductivity, as well as containing large unit cells, structural complexity, and the presence of heavy elements. Zintl compounds containing heavy main group elements such as Sb and Bi meet all of these requirements. This proposal emphasizes the current paradigm as a starting place to look for materials with a high figure-of-merit that will be compatible with existing materials for a device that will be able to operate under large temperature gradients. The project focuses on a search for new materials. It engages graduate students and undergraduates as well as high school teachers and students in exploratory research on new materials. They learn about synthetic design and are involved in using state of the art techniques in characterization. Non-Technical Abstract: Thermoelectric devices are environmentally benign power sources that provide one solution to energy requirements through the direct conversion of heat into electrical energy. These devices require little-to-no fuel, minimal maintenance, and can operate over a large temperature range (300 1275 K). This is an area of research where new materials have the potential for reducing cost while increasing efficiency. Zintl compounds represent a class of largely unexplored phases with many of the desired characteristics for good thermoelectric properties. These compounds are semiconductors with large, complex structures that can be easily doped and modified to optimize desired properties. This multidisciplinary project trains postdoctoral, graduate and undergraduate students in the synthesis and characterization of new compounds. Outreach to the community in terms of research opportunities in energy related projects for high school students and teachers encourages future scientists and increases the number in the science pipeline.