Temperature dependent solubility of Yb in Yb–CoSb3 skutterudite and its effect on preparation, optimization and lifetime of thermoelectrics

Yinglu Tang, Sinn wen Chen, G. Jeffrey Snyder*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

79 Scopus citations

Abstract

Although filled skutterudites are actively being developed for automotive waste heat recovery the compositions considered available are limited. Typically synthesis conditions are chosen with slight excess filling element to produce filled skutterudites at the ‘filling fraction limit’, traditionally considered to be a single value that depends only on the elements involved (e.g. filling element, Co/Fe ratio). The filling fraction limit is often debated and thought perhaps to vary with processing method. This work opens up a new dimension of available compositions by showing that the ‘filling fraction limit’ is a thermodynamic quantity that for Yb varies by a factor of 5 depending on annealing temperature and nominal composition. As the filling element controls the electronic doping in these semiconductors this study not only enables optimization of thermoelectric properties using thermodynamic control rather than non-equilibrium processing conditions (reaching zT = 1.3 at 850 K without nanostructures) but it also predicts dopant precipitation effects after extended use. The novel phase diagram approach used here should be easily applied to other ternary thermoelectric materials to uncover similar phenomena. Thus skutterudite material with the optimized thermoelectric composition can be produced from a range of nominal compositions with appropriate annealing.

Original languageEnglish (US)
Pages (from-to)75-84
Number of pages10
JournalJournal of Materiomics
Volume1
Issue number1
DOIs
StatePublished - Mar 1 2015

Keywords

  • Optimization
  • Skutterudites
  • Temperature dependent solubility
  • Thermoelectric

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Metals and Alloys

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