SrTiO₃is a promising thermoelectric material for high temperature application of waste heat electrical generation.

Herein, we propose for the first time a novel recipe to improve the thermoelectric properties of BiCuSeO by doping with variable valence elements. Taking Yb-doped BiCuSeO as a typical example, the dimensionless figure of merit (ZT) is optimized by simultaneously doping with Yb²⁺ to increase the carrier concentration and by introducing Yb³⁺ to increase the carrier mobility. The mechanisms of valence fluctuation, the increase in carrier concentration and the increase in mobility are investigated by combining experimental results with first-principles calculations. By coupling high electronic conductivity, medium Seebeck coefficient, and low thermal conductivity, a maximum ZT value of 0.62 is achieved at 823 K for Bi_0.7Yb_0.3CuSeO, which is 1.55 times higher than that of pristine BiCuSeO. These findings undoubtedly provide a new strategy for the rational design of high-ZT thermoelectric materials.

A nano Cu₅Zr and micro ZrB₂ dual-scale particulate-reinforced copper matrix composite is prepared by in situ synthesis and heat treatment, which has high strength, high electrical conductivity and superior wear resistance.