摘要
TiFe0.5Ni0.5Sb-based half-Heusler compounds have the intrinsic low lattice thermal conductivity and the adjustable band structure.Inspired by the previously reports to achieve both p-and n-type components by tuning the ratio of Fe and Ni based on the same parent TiFe0.5Ni0.5Sb,we selected Co as the amphoteric dopants to prepare both n-type and p-type pseudo-ternary Ti(Fe,Co,Ni)Sb-based halfHeusler alloys.The carrier concentration,as well as the density of states effective mass was significantly increased by Co doping,contributing to the enhanced power factor of 1.80 mW m^(-1) K^(-2) for n-type TiFe0.3Co_(0.2)Ni_(0.5)Sb and 2.21 mW m^(-1) K^(-2) for p-type TiFe_(0.5)Co_(0.15)Ni_(0.35)Sb at 973 K.Combined with the further decreased lattice thermal conductivity due to the strain field and mass fluctuation scattering induced by alloying Hf on the Ti site,peak ZTs of 0.65 in n-type Ti0.8Hf_(0.2)Fe_(0.3)Co_(0.2)Ni_(0.5)Sb and 0.85 in ptype Ti0.8Hf_(0.2)Fe_(0.5)Co_(0.15)Ni_(0.35)Sb were achieved at 973 K,which is of great significance for the thermoelectric power generation applications.
基金
the National Natural Science Foundation of China(51971081,11674078,and 51871081)
the Cheung Kong Scholar Reward Program Young Scholar Program of China(Q2018239)
the Natural Science Foundation for Distinguished Young Scholars of Guangdong Province of China(2020B1515020023)
the China Scholarship Council project,the Natural Science Foundation of Guangdong Province of China(2018A0303130033)
Shenzhen Science and Technology Innovation Plan(KQJSCX20180328165435202).
