Effect of Chemical Plating with Ni Content on Thermoelectric and Mechanical Properties of P-Type Bi_0.5Sb_0.15Te₃ Bulk Alloys

Abstract

In this work, Bi0.5Sb1.5Te3 powders were coated with various nickel (Ni) contents by chemical plating, and then consolidated into bulk by hot pressing. The results show that Ni particles uniformly coat on the surface of powders and then transform into NiTe2 during the sintering process, after that NiTe2 mainly concentrated at the grain boundaries of bulk. With Ni content increasing, the resistivity of bulk samples and Seebeck coefficient decreased rapidly while thermal conductivity increased. The maximum value of ZT for Bi0.5Sb1.5Te3/Ni sample with 1wt.% Ni is 0.55. Moreover, due to the excellent ductility of Ni that can act as lubricant and binder during the hot pressing process, making the mechanical properties (hardness) of bulks elevated with Ni content increasing. This work suggests that chemical plating technology can improve the mechanical properties and impact the thermoelectric properties of thermoelectric materials. With further tuning the type and content of coating elements, the thermoelectric performance can be improved prospectively.