Synthesis and transport properties of HfFe4Sb12

We have synthesized, characterized, and measured the low-temperature transport properties of the metastable skutterudite HfFe4Sb12⁠. HfFe4Sb12 was synthesized by depositing successive very thin elemental layers of Hf, Fe, and Sb, in the appropriate stoichiometric quantities, over a relatively large polymer coated substrate. Low-temperature annealing of this film resulted in the direct crystallization of the desired skutterudite. The skutterudite film was removed from the substrate by dissolving the polymer film and the resulting powder was densified utilizing standard powder metallurgical techniques. The HfFe4Sb12 skutterudite possesses a very low thermal conductivity; lower than that of other lanthanide-filled skutterudites while exhibiting p-type conduction. Although the room-temperature dimensionless thermoelectric figure of merit of this compound is low compared to thermoelectric materials in use today, it is in the range of the best p-type skutterudite compounds thus far reported. More importantly, this synthesis technique opens the possibility of producing bulk specimens of metastable compounds that are of interest for thermoelectric and other technological applications.