Dresden 2026 – wissenschaftliches Programm

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FM: Fachverband Funktionsmaterialien

FM 22: Focus Session: Materials Discovery III – New materials and functionalities by general principles

FM 22.3: Vortrag

Freitag, 13. März 2026, 10:15–10:30, BEY/0138

Ta2PdSe6: A guide towards high performance thermoelectric semimetals — •Akitoshi Nakano — Nagoya University, Nagoya, Japan

We have recently discovered that a transition-metal chalcogenide Ta2PdSe6 exhibits an extraordinary thermoelectric property despite its semimetal character. Ta2PdSe6 crystallizes in a layered structure, each layer of which consists of quasi-one-dimensional chains formed by prismatic TaSe6 and square-planner PdSe4. The thermoelectric property measured along this direction is highly exotic; an ultra-high conductivity (σ) above 10^6 Ω^-1cm^-1 is compatible with a substantial thermopower (S) of 40 μVK^-1 at 20K. As a result, the power factor (= S^2σ) reaches above 2000 μWcmK^-2, which is top level among bulk thermoelectric materials thus far.

Furthermore, we have found that the thermal conductivity of Ta2PdSe6 is relatively small (~ 100 Wm^-1K^-1) for such a good electrical conductor associated with a serious violation of the Wiedemann-Franz law. As a result, the thermoelectric figure of merit Z (= S^2σκ^-1) of Ta2PdSe6 at 14 K reaches as high as 3*10^-3 (K^-1), which is comparable to Bi2Te3 at 300 K.

In the presentation, we will discuss the origin of the anomalous transport properties of Ta2PdSe6 from the viewpoint of the carrier dynamics.

Keywords: General principles; Thermoelectric semimetal; transition metal chalcogenide; one-dimensional material