Synthesis-temperature-dependent phase composition manipulation toward high thermoelectric performance in tetrahedrites

Tetrahedrite,an Earth-abundant natural mineral,has attracted extensive research interest because of its excellent thermoelectric performance.Herein,tetrahedrite samples comprising Cu-poor Cu_(12)Sb_(4)S_(13)and Cu-rich Cu_(14)Sb_(4)S_(13)phases have been synthesized using a colloidal method,in which the ratio of two phases is manipulated by controlling the synthesis temperature to improve the thermoelectric perfor-mance.It is found that an ultralow total thermal conductivity of∼0.3 W m^(−1)K^(−1)at 723 K is realized in the sample with a Cu-rich phase fraction of∼50%,which can be attributed to maximized phonon scattering by phase boundaries.As a result,combined with a decent power factor,this sample obtains an optimal zT of 1.15,which is about 85%higher than that of the sample with a Cu-rich phase fraction of∼64%and comparable to zT values of other eco-friendly,abundant Cu-based thermoelectric materials.This work demonstrates an effective synthesis-temperature-dependent phase composition manipulation strategy toward enhanced thermoelectric performance in tetrahedrites.