Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5447800 | Materials Chemistry and Physics | 2017 | 6 Pages |
Abstract
Na2Fe2Ti6O16 freudenbergite has been synthesized using a simple solid-state route and conventionally sintered to reach 94% density ceramics. High temperature electrical and thermal transport properties have been investigated for the first time. In the temperature range of 468 K-1000 K, the electrical conductivity of Na2Fe2Ti6O16 can be well fitted with small polaron hopping model. For a further verification of the model, we measured the room-temperature optical reflectivity and derived the optical conductivity (Ï(Ï)) with Kramers-Kronig analysis. A mid-infrared peak in Ï(Ï) confirms the presence of small polarons. From 468 K to 1000 K, Na2Fe2Ti6O16 is an n-type oxide and exhibits a temperature-independent Seebeck coefficient (â¼â590 μV Kâ1), in agreement with the small polaron hopping mechanism. The thermal conductivity decreases with increasing temperature from 16.5 W mâ1.Kâ1 (373 K) to 3.4 W mâ1.Kâ1 (1000 K). Na2Fe2Ti6O16 shows a maximum figure of merit (ZT) â¼ 3 Ã 10â4 at 1000 K.
Related Topics
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Authors
Cong Chen, Fabien Giovannelli, Mustapha Zaghrioui, Loïc Perriere, Fabian Delorme,