Carrier concentration tuning in thermoelectric thiospinel Cu2CoTi3S8 by oxidative extraction of copper

We report a method for carrier concentration tuning in the thermoelectric thiospinel Cu2CoTi3S8, which exhibits an n-type metallic character and a high power factor. An oxidative Cu extraction treatment produced Cu defects, resulting in Cu2−x CoTi3S8 up to x = 0.62. The electron carrier concentration was effectively reduced by this treatment, leading to the decrease in power factor, whereas the electronic contribution to the thermal conductivity was suppressed. As a result, the dimensionless figure of merit ZT remained unchanged as 0.2 at 670K in the whole range of x ≤ 0.62. The oxidative Cu extraction described in this paper offers an opportunity to tune the electron carrier concentration for Cu-containing thermoelectric materials. Graphical abstract

Source: Journal of Solid State Chemistry - January 5, 2018 Category: Chemistry Source Type: research