Berlin 2008 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 51: Materials Design II
MM 51.3: Vortrag
Freitag, 29. Februar 2008, 12:15–12:30, H 0111
Probing the rattling mode scenario in nano-cage based thermoelectric materials — Andreas Leithe-Jasper1, Yuri Grin1, Walter Schnelle1, Romain Viennois1, Hannu Mutka2, Lucia Capogna2, Mark Robert Johnson2, and •Michael Marek Koza1,2 — 1MPI-CPfS, Noethnitzer Strasse 40, D-01187 Dresden — 2ILL, 6 Rue Jules Horowitz, F-38042 Grenoble
The direct conversion of waste heat into electrical power in thermoelectric devices is believed to contribute substantially to future power supply and sustainable energy management. Nanocage-based crystalline structures like filled skutterudite systems XFe4Sb12 (X = Ca, Cs, Ba, La, Ce, Yb, Nd, ...) and clathrate materials like BaGe and BaSi have attracted some scientific interest as they are sought to be excellent thermoelectric materials. Their applicability for an efficient conversion of thermal into electrical energy is based on the opportunity of tuning appreciably the heat transport through the sample leaving the electron transport rather unaffected.
We will give some examples of our experimental work comprising neutron scattering techniques and bulk spectroscopies, e.g. specific heat measurements, on filled skutterudite systems and pyrochlore osmates XOs2O6 (X = K, Rb, Cs). We will present a new approach based on ab initio lattice dynamics calculations towards the interpretation of experimental data particularly dedicated to polycrystalline systems. We will show that the apparently established picture of rattling modes, i.e. decoupled dynamics of guests X and host Fe4Sb12 is not correct.