Fabrication of large sintered pellets of Sb-doped N-type Mg2Si using a plasma activated sintering method

Abstract

Sb is known to be the most stable n-type dopant in Mg2Si, whereas the reproducibility and sintering scalabity of Sb-doped Mg2Si has proved to be difficult. We have developed a metallic binder for the Sb-doped Mg2Si sintering process. A remarkable benefit of the binder is that it enables us to reproducibly fabricate large sintered Sb-doped Mg2Si pellets up to 30 mm in diameter with no internal cracks. For binder contents of 3 to 7 wt%, the observed power factor and thermal conductivity were identical to that of conventional Sb-doped samples, while excess binder degraded the TE properties. The binder mixture also plays a part in increasing the yield in the production of TE legs, up to 82% for 5 wt% Ni incorporation, as well as improving the hardness of the sintered sample. Incorporation of 5 wt% Ni binder affected an increase in the ZT value up to 0.97.