Low-temperature structure and thermoelectric properties of ductile Ag2S0.4Te0.6

Ductile Ag 2 S 0.4 Te 0.6 shows promising thermoelectric properties and interesting phase transitions and structural features above room temperature. In this work, our experiments reveal that Ag 2 S 0.4 Te 0.6 is composed of a Ag 2 Te-based glass and a Ag 2 S-based supercooled liquid at room temperature. The Ag 2 Te-based glass preserves its amorphous state in the measured temperature range (20–303 K), while the Ag 2 S-based supercooled liquid crystallizes into a triclinic phase below 183 K, leading to respectively the glass and crystalline-like thermal transport of Ag 2 S 0.4 Te 0.6 near room temperature and at low temperature. At the crystallization point of the Ag 2 S-based phase, the electrical conductivity of Ag 2 S 0.4 Te 0.6 shows an anomalous change. The extremely wide supercooling region (183–420 K) of the Ag 2 S-based phase leads to the unprecedented ductility of Ag 2 S 0.4 Te 0.6 . The thermoelectric figure of merit zT of Ag 2 S 0.4 Te 0.6 increases monotonically with increasing temperature and reaches ∼0.17 at 300 K, showing the great potential as a ductile thermoelectric inorganic.