Defect chemistry and thermoelectric properties of doped Delafossite-type oxide CuFeO2

Titelangaben

Stöcker, Thomas ; Moos, Ralf ; Rüger, Reinhold:
Defect chemistry and thermoelectric properties of doped Delafossite-type oxide CuFeO2.
2013
Veranstaltung: 2nd International Conference on Materials for Energy, EnMat II , 12.-16.05.2013 , Karlsruhe, Germany.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Poster )

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Abstract

In the field of thermoelectric energy conversion, oxide materials show a promising potential due to their good stability in oxidizing environments. Delafossite materials exhibit a good thermoelectric performance as p-type as well as n-type oxide semiconductors at elevated temperatures and can be doped with various transition metals by solid-state mixed oxide routes. Cu-based Delafossite oxides were synthetized by a conventional mixed-oxide technique with varying Ni- and Sn-content. The so prepared specimens were fired in oxygen-rich atmospheres with changing oxygen partial pressures. X-ray diffraction studies were conducted to determine the crystal structures of the doped Delafossites. By using a modulation heater to impress an oscillating temperature gradient over the samples, the thermopower was investigated between 300 K and 1100 K under defined oxygen partial pressures. In order to evaluate the thermoelectric conversion performance, quantified by the dimensionless figure of merit ZT, the electrical and the thermal conductivities were also measured. In addition, the electrical conductivity and the Seebeck coefficient were recorded as a function of the oxygen partial pressure to determine defect chemical constants in order to develop the basics of a defect chemical model of Cu-based Delafossites.