Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 44: Functional Materials II
MM 44.7: Vortrag
Freitag, 18. März 2011, 12:00–12:15, IFW A
SrTi1−xNbxO3−δ glass-ceramics as oxidic thermoelectric materials — •Julian Lingner1,2, Martin Letz1, and Gerhard Jakob2 — 1Schott AG, Hattenbergstraße 10 Mainz — 2Johannes Gutenberg-Universität Mainz
Thermoelectrics are materials that convert waste heat into electrical power. The quality of a thermoelectric substance is characterized by the dimensionless figure of merit ZT=S2σ /κT. One essential advantage of glass-ceramics is their low thermal conductivity κ together with the high temperature stability of up to 700∘C. The crystal phase SrTiO3 is a wide bandgap semiconductor, doping with niobium and with oxygen vacancies shifts the Fermi level into the donor band resulting in a insulator-metal transition. Furthermore, nanoscale structure offers a possibility to improve the performance and allows to adjust the material to the required application. Nano crystalline conducting crystal grains effectively reduce the dimensionality of the conducting material, which allows to modify the density of states and therefore the Seebeck coefficient S and the electrical conductivity σ, thus increasing the thermoelectric figure of merit. Using a short range infrared heat treatment, a controlled crystallization in the glass samples can be induced so that nanoscale SrTiO3 crystals are formed in the glass-ceramic. We show results of thermoelectric properties of first glass-ceramic systems containing doped SrTiO3.