Effect of the annealing treatment on structural and transport properties of thermoelectric Sm y (Fe x Ni 1-x ) 4 Sb 12 thin films.

The crystallographic and transport properties of thin films fabricated by pulsed laser deposition and belonging to the Sm y (Fe x Ni 1-x ) 4 Sb 12 filled skutterudite system were studied with the aim to unveil the effect exerted by temperature and duration of thermal treatments on the thermoelectric and structural features of the films. The importance of annealing treatments in Ar gas atmosphere up to 523 K was recognized, and the thermal treatment performed at 473 K for 3 hours was selected as the most effective in improving the material properties. With respect to the corresponding bulk compositions, a significant enhancement in phase purity, as well as an increase in electrical conductivity and a drop in room temperature thermal conductivity, were observed in annealed films. The low thermal conductivity, in particular, can be deemed as deriving from the reduced dimensionality and the consequent substrate/film interfacial stress, coupled with the nanometric grain size.