Fast phase formation of double-filled p-type skutterudites by ball-milling and hot-pressing.

Filled-skutterudites are promising mid-temperature thermoelectric materials for heat-to-electricity conversion. Traditional preparation methods need a very long time annealing (7 to 14 days) to form the right skutterudite phase. Annealing is especially critical for p-type filled-skutterudites, since Fe4Sb12 needs filler atoms to enter the cage to form a stable phase. In this work, we prepared Ce and Nd double-filled p-type skutterudite materials by directly ball-milling the quenched ingot without annealing followed by hot-pressing. The results showed that with appropriate ball-milling time, a pure p-type filled-skutterudite phase can be obtained in just 5 minutes by hot-pressing. The samples prepared in this way have the same quality as those prepared by traditional long time annealing methods, and showed ZT values above 1 between 700 and 800 K. This simple and efficient method is very useful for the preparation of many other materials that are kinetically difficult to make.