Effect of Cu concentration on thermoelectric properties of nanostructured p-type MgAg0.97−xCuxSb0.99

Recently, MgAgSb was discovered to have good thermoelectric properties. In this paper, we intend to substitute a small amount of Ag by Cu to make MgAg0.97−xCuxSb0.99 (x = 0, 0.003, 0.007, and 0.01) thermoelectric materials aiming to decrease the lattice thermal conductivity without sacrificing the power factor. The results showed that Cu substitution not only reduced the thermal conductivity, but also improved the power factor, consequently led to improved ZT values. Among the MgAg0.97−xCuxSb0.99 samples, MgAg0.963Cu0.007Sb0.99 showed the highest ZT values of 0.95 at room temperature and 1.32 at 250 °C. In addition, the MgAgSb-based samples displayed much better self-compatibility factors than Bi0.4Sb1.6Te3. The effect of grain orientation on the anisotropy of thermoelectric properties of MgAg0.97Sb0.99 has also been studied.