Structural and electrical transport properties of Se-substituted p-type Bi_2Se_(3x)Te3_(（1-x）) (x=0.0-1.0) alloys prepared by solid-state microwave synthesis

摘要

In this study, thermoelectric materials based on p-type Bi_2Te_3 and dispersed with x compositions of selenium (Se) (x=0.0, 0.2,0.4, 0.6,0.8,and 1.0) in Bi_2Se_(3x)Te3_((1-x)) ingots were synthesized using a standard solid-state microwave method. The crystalline structures of the polycrystalline powders were examined by X-ray diffraction (XRD), which showed the formation of a rhombohedral structure. The surface morphology for the samples showed that the Se alloying is an effective approach for crystalline refinement, which has been characterized by scanning electron microscopy (SEM). The electrical transport properties of the samples were measured from room temperature up to 500 K. The results indicate that the selenium substitution effectively adjusts the carrier concentration allowing an optimum value of 1.25 x 10~(20) cm~(-3), Ascribing to the increased Seebeck coefficient for the sample with x=0.2 (176.3 μV/K), the maximum power factor is 2.85 mW/mK~2 at 403 K.