Nanostructuring of p- and n-type skutterudites reaching figures of merit of approximately 1.3 and 1.6, respectively

• Published in: Acta materialia 2014-09, Vol.76, p.434-448
• Main Authors: Rogl, G., Grytsiv, A., Rogl, P., Bauer, E., Hochenhofer, M., Anbalagan, R., Mallik, R.C., Schafler, E.
• Format: Article
• Language: English
• Subjects: Applied sciences; Conversion; Crystallites; Exact sciences and technology; Figure of merit; Grain size; Hardness; Hot pressing; Metals. Metallurgy; Mischmetal; Nanostructure; Nanostructured materials; Strainers; Thermoelectricity; Thermoelectrics; Transport properties
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2014.05.051

[Display omitted] Thermoelectric (TE) conversion of waste heat into useful electricity demands optimized thermal and electrical transport in the leg material over a wide temperature range. In order to gain a reasonably high figure of merit (ZT) as well as high thermal–electric conversion efficiency, various conditions of the starting material were studied: industrially produced skutterudite powders of p-type DDy(Fe1−xCox)4Sb12 (DD: didymium) and n-type (Mm,Sm)yCo4Sb12 (Mm: mischmetal) were used. After a rather fast reaction-melting technique, the bulk was crushed and sieved with various strainers in order to obtain particles below the respective mesh sizes, followed by ball-milling under three different conditions. The dependence of the TE properties (after hot pressing) on the micro/nanosized particles, grains and crystallites was investigated. Optimized conditions resulted in an increase of ZT for bulk material to current record-high values: from ZT∼1.1 to ZT∼1.3 at 775K for p-type and from ZT∼1.0 to ZT∼1.6 at 800K for n-type, resulting in respective efficiencies (300–850K) of η>13% and η∼16%.