Dresden 2009 – scientific programme

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DS: Fachverband Dünne Schichten

DS 16: Poster I

DS 16.34: Poster

Tuesday, March 24, 2009, 09:30–12:30, P5

Preparation of thin cobaltate and manganite films for thermoelectric applications — •Stefanie Wiedigen, Thilo Kramer, Jörg Hoffmann, and Christian Jooss — Institute of Material Physics, University of Goettingen, Germany

Complex oxides like cobaltates and manganites are promising thermoelectric materials because of their large Seebeck coefficient and their chemical and thermal stability at elevated temperatures. Due to their poor electric conductivity, ZT is relatively low (≈ 0.02). It is therefore interesting to evaluate the potential for ZT enhancement by decoupling of the electric and the thermal transport. In this contribution we analyze structural and transport properties of cobaltate and manganite thin films prepared by ion-beam sputtering. For the manganite system, we choose the hole doped Pr_1−xCa_xMnO₃ (x=0.32) system with strong electron-phonon coupling. It is shown that the electric conductivity is governed by small polaron hopping. For the cobaltate system we choose CaCoO₃ and PrCoO₃ compositions as the starting point for the analysis of electric and thermal conductivity at low electron and hole doping. First results concerning such cobaltate films produced by ion-beam sputtering are presented. The relation between doping, structure and electric conductivity is analyzed. We discuss our results in the light of polaron conductivity mechanism and its impact on designing thermoelectric properties.