Synthesis and structural evolution of rusb3, a new metastable skutterudite compound.

A thin-layer synthesis technique was used to synthesize bulk amounts of the metastable phase, RuSb(3), a novel compound with the skutterudite structure. The compound crystallized at 350 degrees C and was stable to 525 degrees C. When annealed above 550 degrees C, it decomposed into RuSb(2) and Sb. Rietveld refinement of X-ray diffraction data showed the presence of excess Sb residing in the interstitial site in the skutterudite structure. X-ray diffraction and thermal analysis experiments allowed us to examine the evolution of the sample as a function of annealing and determine the reaction pathway. The activation energy for the crystallization of the compound was determined to be 3 eV/nucleation event, while the activation energy for decomposition was approximately 8 eV.