Determining the effect of Ru substitution on the thermal stability of CeFe4−xRuxSb12

The ternary, rare-earth filled (RE) Skutterudites (REM4Pn12; M = Fe–Os; Pn = P–Sb) have been proposed for use in high-temperature thermoelectric devices to convert waste heat to useful power. CeFe4Sb12 has been one of the most popular materials proposed for this application; however, it oxidizes at relatively low temperatures. The thermal stability of Skutterudites can be enhanced by selective substitution of the constituent elements and Eu(Fe,Ru)4Sb12 variants have been found to oxidize at temperatures above that of CeFe4Sb12. Unfortunately, these materials have poor thermoelectric properties. In this study, the thermal stability of CeFe4−xRuxSb12 was examined depending on the value of x. (These compounds have similar thermoelectric properties to those of CeFe4Sb12.) It has been found by use of TGA and XANES that the temperature at which point CeFe4−xRuxSb12 oxidizes increases with greater Ru substitution. XANES was also used to confirm the general charge assignment of Ce3+Fe4−x2+Rux2+Sb121−.

The thermal stability of CeFe4−xRuxSb12 in air has been investigated using thermogravimetric analysis and X-ray absorption near-edge spectroscopy. The temperature at which point the material oxidizes increases with greater Ru content.Figure optionsDownload as PowerPoint slideHighlights
► The thermal stability of CeFe4−xRuxSb12 increases with greater Ru content.
► Ru in CeFe4−xRuxSb12 oxidizes and is then reduced at high temperatures.
► XANES confirmed the charge assignments in these materials as Ce3+Fe4−x2+Rux2+Sb121−.