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A2: Medium temperature materials

Ultra-fast synthesis and thermoelectric properties of Te doped skutterudites

Tao Liang1, Xianli Su1, Yonggao Yan1, Gang Zheng1, Qiang Zhang1, Hang Chi2, Xinfeng Tang1,a , and Ctirad Uher2
1State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 43007, China2Department of Physics, University of Michigan, Ann Arbor, Michigan.

The Self-propagating-High-temperature-Synthesis (SHS) technique is applied here for the first time to synthesize CoSb3 thermoelectric materials. Mixtures of Co and Sb powders were compacted into pellets which were ignited from one end. Single-phase skutterudite material was obtained in a very short period of time using the SHS process which is maintained by the heat released from the chemical reaction of Co with Sb. Thermodynamic parameters and kinetics of the SHS reaction are investigated. The ignition temperature, adiabatic temperature, and the propagation speed of the combustion wave in the synthesis of CoSb3 are 723 K, 861 K, and 1.25 mm/s, respectively. Using the SHS technique followed by Plasma Activation Sintering (PAS), we synthesized high performance bulk skutterudites of composition CoSb2.85Te0.15 with a maximum dimensionless thermoelectric figure of merit ZT of 0.98 at 820 K, one of the highest ZT values for an unfilled form of skutterudites. Compared with the samples synthesized by the traditional methods via long time annealing, the synthesis time is shortened from the typical 10 days to less than 20 minutes. Our work opens a new avenue for ultra-fast, low cost, mass production fabrication of skutterudite-based materials, which may also be universally applicable for the synthesis of other thermoelectric materials.