High Efficiency Lanthanide Thermoelectric Materials for Space Applications

Sabah Bux, Ph.D.
Senior Member of Technical Staff
Thermal Energy Conversion Research
and Advancement Group
Jet Propulsion Laboratory/California Institute of Technology

For more than 50 years, radioisotope thermoelectric generators (RTGs) have been used successfully to power U.S. space missions, including NASA’s deep space probes such as Voyagers 1 and 2, Cassini to Saturn, and the recently landed Curiosity Mars rover.   The state-of-the-art thermoelectric materials for space have typically been based up on either SiGe alloys or PbTe. Although reliable/robust, the performance of these systems remains fairly  low.  In  recent  years,  complex  materials  such  as  n-type  La3-xTe4  and  p-type Yb14MnSb11  have  emerged  as  new  high  efficiency,  high  temperature  thermoelectric materials. The high performance of these materials is attributed to their favorable electronic and thermal characteristics such as: semi-metallic behavior due to small band gaps, low glass-like  lattice  thermal  conductivity  values  due  to  structural  complexity  and  reasonably large  thermopower  values  near  their  peak  operating  temperatures.  We  will  present  an overview of recent research efforts at JPL and collaborating institutions on these material systems and will discuss approaches and preliminary results on improving the efficiency of these materials through a combination of first principle electronic structure simulations and empirical experimental research.

Sabah  Bux  received  her  Bachelors  of  Science  in  Chemistry,  Magna  Cum  Laude  from California State Polytechnic University Pomona in 2005 and received her Ph.D. in inorganic chemistry  from  UCLA  in  2010.  Currently  she  is  a  techonologist  at  the  Jet  Propulsion Laboratory  working  in  the  thermal  energy  conversion  research  and  advancement  group (3464)  where  she  is  the  lead  researcher  and  task manager  in  the  development  of  high performance advanced thermoelectric materials for space applications. Her main research focus  is  the  investigation  of  new  materials  and  synthesis  of  them  using  novel  synthetic techniques/processes.  She  holds  several  patents  and  publications  on  the  synthesis  and characterization of materials such as nanostructured Si1-xGex alloys, Mg2Si, and silicon-based composites, III-V semiconductors, metal-matrix composites and complex Zintl phases. She received the 2015 International Thermoelectrics Society Young Investigator award and is the 2017 recipient of the JPL Lew Allen early career award for excellence in research and technology.