Berlin 2015 – scientific programme
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DS: Fachverband Dünne Schichten
DS 10: Thermoelectric materials
DS 10.3: Talk
Tuesday, March 17, 2015, 10:00–10:15, H 0111
Reduced thermal conductivity of TiNiSn/HfNiSn superlattices — •Paulina Holuj1,3, Christoph Euler1, Tino Jaeger1, Benjamin Balke2, and Gerhard Jakob1,3 — 1Institute of Physics, University of Mainz, Staudinger Weg 9, 55128, Germany — 2Institute of Inorganic and Analytical Chemistry, University of Mainz, Staudinger Weg 9, 55128, Germany — 3Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128, Germany
Thermoelectric materials possess the ability to convert unused heat to electricity. The efficiency of their operation depends on the dimensionless figure of merit ZT=S2σ/κ that contains only material dependent parameters (S - Seebeck coefficient, σ - electrical conductivity, κ - thermal conductivity). The goal of our work is to reduce thermal conductivity and doing so we aim to enhance ZT. Reduction of κ is achieved by scattering of phonons at interfaces of superlattices (SL) made out of TiNiSn and HfNiSn half-Heusler materials. Based on x-ray diffraction we assume to have sharp interfaces between constituent layers. In the current study we observe a systematic reduction of the thermal conductivity as the period of the SLs is decreasing with a clear minimum at about 3 nm and a further increase of κ due to formation of an artificial crystal.
We gratefully acknowledge financial support by DFG (Ja821/4-2) and the Graduate School of Excellence Material Science in Mainz (GSC 266).