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Abstract

The rapid growth of the thermoelectric cooler market makes the development of novel room temperature thermoelectric materials of great importance. Ternary n-type Mg-3(Bi,Sb)(2)alloys are promising alternatives to the state-of-the-art Bi-2(Te,Se)(3)alloys but grain boundary resistance is the most important limitation. n-type Mg-3(Bi,Sb)(2)single crystals with negligible grain boundaries are expected to have particularly highzTbut have rarely been realized due to the demanding Mg-rich growth conditions required. Here, we report, for the first time, the thermoelectric properties of n-type Mg-3(Bi,Sb)(2)alloyed single crystals grown by a one-step Mg-flux method using sealed tantalum tubes. High weighted mobility similar to 140 cm(2)V(-1)s(-1)and a highzTof 0.82 at 315 K are achieved in Y-doped Mg(3)Bi(1.25)Sb(0.75)single crystals. Through both experimental angle-resolved photoemission spectroscopy and theoretical calculations, we denote the origin of the high thermoelectric performance from a point of view of band widening effect and electronegativity, as well as the necessity to form high Bi/Sb ratio ternary Mg-3(Bi,Sb)(2)alloys. The present work paves the way for further development of Mg-3(Bi,Sb)(2)for near room temperature thermoelectric applications.