An argyrodite-type Ag9GaSe6 liquid-like material with ultralow thermal conductivity and high thermoelectric performance.

We report a ternary argyrodite-type Ag9GaSe6 compound as a promising thermoelectric material in a moderate temperature range. Due to high carrier mobility and ultralow lattice thermal conductivity, a maximum ZT of 1.1 was obtained with stoichiometric Ag9GaSe6 at 800 K. Via introducing slight Se-deficiency to optimize the carrier concentration, the maximum ZT is further enhanced to 1.3. [ABSTRACT FROM AUTHOR]