Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 15: Thermoelectric Materials
DS 15.2: Talk
Tuesday, March 8, 2016, 10:00–10:15, H8
Symmetrical and non-symmetrical TiNiSn/HfNiSn superlattices — •Paulina Komar1,2, Emigdio Chávez Angel1, Christoph Euler1, Gregor Fiedler3, Benjamin Balke4, Peter Kratzer3, and Gerhard Jakob1,2 — 1Institute of Physics, University of Mainz, Mainz, Germany — 2Graduate School Materials Science in Mainz, Mainz, Germany — 3Faculty of Physics, University of Duisburg-Essen, Duisburg, Germany — 4Institute of Inorganic and Analytical Chemistry, University of Mainz, Mainz, Germany
The goal of our work is to reduce the thermal conductivity by phonon scattering at the superlattice (SL) interfaces and enhance ZT=S2σ/κT. For symmetrical SLs (TiNiSn:HfNiSn ratio=1 and variable SL period) we observe a very good agreement between the cross-plane thermal conductivity measured by the 3ω method and a calculation based on Boltzmann transport theory down to a SL period of 3 nm. At the SL period of 3 nm a crossover between the particle- and the wave-like transport of phonons takes place and, therefore, κ increases for decreasing periods [1]. An investigation of non-symmetrical SLs (variable TiNiSn:HfNiSn ratio and constant SL period) reveal that not only the SL period and the number of interfaces have an influence on κ, but the ratio of materials with higher and lower κ influences the thermal conductivity as well. Additionally, a systematic improvement of the in-plane Seebeck coefficient is observed.
We gratefully acknowledge financial support by DFG (Ja821/4-2) and (GSC 266).
[1] P. Hołuj et al. Phys. Rev. B 92, 125436 (2015).