We Have Moved to Northwestern!
The Snyder Group will continue to specialize in Thermoelectric Materials and Devices as well as expand into other Materials for Energy fields. Interested students are encouraged to apply to the top ranked MSE department at Northwestern University. Close collaboration with NASA-Jet Propulsion Laboratory will contiune.
For her work on understanding the electronic structure and phase relations for optimizing Skutterdite thermoelectric materials. Yinglu is now Postdoc at EMPA in Switzerland.
For her work on novel and nanostructured thermoelectric materials.
For his Ph.D. work on Band Engineering and PbSe.
For her Ph.D. work on new Zintl phase thermoelectric materials. Alex is now an assistant professor at Michigan State University.
For his work on band engineering of thermoelectric materials. Former Posdoc Yanzhong Pei (裴艳中) is Professor of Materials Science at Tonji University in Shanghai China.
Curiosity Rover Powered by Thermoelectrics Lands on Mars
The newest Mars rover from NASA JPL uses PbTe-based thermoelectrics for power. News and Video
Skutterudites, based on CoSb3, are the new thermoelectric materials most developed to supplant Bi2Te3 and PbTe based materials in space and commercial applications. Their complex electronic and atomic structures gives them ideal eletrical and thermal properties for thermeoelectrics
Dislocation Arrays at Grain Boundaries
Exceptionally low thermal conductivity good Peltier cooling performance was found in Bi2Te3-Sb2Te3 alloys hot pressed with liquid Te. The reduced thermal conductivity with only a small reduction in electron mobility can be explained by low energy grain boundaries consisting of dislocation arrays.
Charge Transport Model for Conducting Polymers and Disordered Materials
A two parameter mathematical model that can explain the experimentally observed relationship between thermopower (Seebeck coefficient) and electrical conductivity demonstrates the insufficiency of the standard hopping models (Variable Range Hopping, and Mobility Edge). This may be an indication of percolation transport between conducting ordered regions (Figure). While the physical mechanism is still unclear, the method will enable quick comparison with theroetical models to uncover transport mechanisms of organic conductors or any non-crystalline, disordered, and/or composite system.
Liquid-Like Thermoelectric Materials
Because a liquid does not propagate shear vibrations the thermal conductivity can be less than that of a solid. Using the liquid-like behaviour of superionic conductors and related highly disordered materials extends the phonon-glass electron-crystal concept for the search for new thermoelectrics.
Band Structure Engineering of PbTe based alloys for Thermoelectrics
Alloys of PbTe have been used to generate electricity from heat on NASA space missions for 50 years and now are being considered for use on Earth for automotive waste heat recovery. Our group has recently demonstrated that the zT of PbTe and PbSe alloys can be tuned to be much better than previously thought possible due, in part, to the exceptionally high valley degeneracy.
Complex Zintl Compounds
The rich solid-state chemistry of Zintl phases enables a directed search and optimization of new complex thermoelectric materials. Several new Zintl Compounds have been found with inherently low thermal conductivity and can be doped to have high zT.