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Berlin 2012 – scientific programme

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DS: Fachverband Dünne Schichten

DS 41: Thermoelectric materials III: Heterostructures (Focused session – Organizers: Meyer, Heiliger)

DS 41.4: Talk

Friday, March 30, 2012, 10:15–10:30, H 2032

Thermal conductivity in Pr1−xCaxMnO3 and SrTiO3 thin film systems — •Stefanie Wiedigen1, Thilo Kramer1, Manuel Feuchter2, Kodanda R. Mangipudi1, Jörg Hoffmann1, Marc Kamlah2, Cynthia A. Volkert1, and Christian Jooss11Institute for Materials Physics, University of Göttingen, Germany — 2Institute for Applied Materials, Karlsruhe Institute of Technology, Germany

Epitaxial multilayers and superlattices are one recent approach for the design of efficient thermoelectrics. To study the effect of phonon blocking and scattering on thermal conductivity of oxide multilayers, a combination of two perovskites with promising thermoelectric properties is selected: the orthorhombic Pr1−xCaxMnO3 and the cubic SrTiO3. In order to investigate the effect of microstructure, interfaces and acoustic impedance mismatch on thermal conductivity κ high preparation quality is needed. Our thin films were prepared by ion-beam and magnetron sputtering. Structural analysis is done by XRD and TEM and will be presented in combination with thermal conductivity measurements using the 3ω method. Single layers of Pr1−xCaxMnO3 show low κ values and no significant increase of thermal conductivty with increasing doping. In homoepitaxial single layers of SrTiO3 preparation conditions have a high impact on κ, most probably due to different concentrations of point defects. Pr1−xCaxMnO3/SrTiO3 multilayers show a κ decreases systematically with increasing number of double layers. The results are discussed in the light of the theoretically calculated phonon dispersion and the experimentally observed microstructure.

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