Zhifeng Ren1

1, University of Houston, Houston, Texas, United States

Significant progress has been made on searching for good thermoelectric materials in the past twenty years. Recently we have made good progresses in finding some new half-Heusler materials with good thermoelectric properties and also improving the properties of some existing half-Heusler materials. For Zintl materials, we discovered that Mg vacancy was the root cause for the strong electron scattering by the ionized impurities causing low electrical conductivity, so we were able to drastically suppress the ionized impurity scattering through replacing a very small amount of Mg by Nb, Fe, Co, Hf, Ta, etc., leading to a higher peak ZT of ~1.8 and drastically higher average ZT of ~1.2 in the temperature range from 300 K to 800 K. These materials may find their potential applications in the mid-high temperature heat sources for power generation.