New Directions in half-Heusler and Metal Phosphide Thermoelectric Materials

Date

Dec 9, 2024

Time

2:00 PM - 3:00 PM

Speaker

Prof. Jan-Willem Bos

Affiliation

University of St. Andrews

Language

en

Main Topic

Materialien

Host

Martina Javorka

Description

Thermoelectric conversion can be used to generate renewable power, scavenge heat and is applied in thermal management. The past 25 years have seen major advancements in materials design and greatly improved thermoelectric performance. However, large-scale application is held back by the high cost compared to grid-price electricity, and technical issues in translating materials performance to generators. Scientifically, the challenge is to find materials that have both low thermal conductivity and outstanding electrical properties, whilst not losing sight of translation into a working technology. This is a difficult challenge but fortunately there is no fundamental limit on the thermoelectric performance. Research in my group has focused on intermetallic half-Heusler materials, and more recently on metal phosphide thermoelectrics. Both are based on abundant elements and could provide a route towards sustainable thermoelectric energy conversion. In the half-Heusler materials, we pioneered the use of interstitial Cu in the leading XNiSn n-type compositions. This enables synergistic reductions of lattice thermal conductivity and improvements in the electronic quality of the materials. Competitive figures of merit, zT = 1 at 793 K are found for compositions with high X = Ti content. Recently, we have used aliovalent alloying as a route to achieve unusually low lattice thermal conductivities, far below expected based on mass and strain disorder. We postulate that this is driven by bond disorder, which also reduces the electronic quality of the materials. This limits the maximum achievable performance, requiring a careful trade-off between thermal and electronic parameters. Metal phosphides are underexplored but offer great structural diversity, often achieving low thermal conductivities, despite low gravimetric densities. The final part of this presentation will give an overview of our recent work on several ternary metal phosphides, including high-mobility CaCuP.

Links

• Seminars at the IFW

Last modified: Dec 9, 2024, 7:36:32 AM