Oxidation Behavior of Filled Skutterudite CeFe4Sb12 in Air
The oxidation behavior of CeFe4Sb12 compound in air was studied in this work. x-Ray diffractometry, scanning electron microscopy observation, and activation energy calculation suggest that CeFe4Sb12 is very easily oxidized at elevated temperature. The reason for the weak resistance to oxidation is mainly due to the unstable “FeSb3” structure and the high Ce filling fraction in the skutterudite voids. At elevated temperature, Ce fillers which have high oxygen affinity firstly react with oxygen. This process proceeds accompanied by decomposition of “Fe4Sb12” into FeSb2 and Sb, which in turn accelerates the oxidation rate. The Ce fillers in CeFe4Sb12 provide a short path for rapid interdiffusion of oxygen, which leads to fast growth of the oxide layer, with thickness of about 200 μm at 900 K after only 1 h exposure in air. This result suggests that appropriate protection from oxidation is necessary for real applications of CeFe4Sb12.