Effects of Different Amount of Se-doping on Microstructures and Thermoelectric Properties of n-type Bi_2Te_(3-x)Se_x

A hydrothermal method combined with a subsequent spark plasma sintering technique was successfully utilized to synthesize selenium(Se) doped bismuth telluride(Bi2Te3-xSex)(0≤x≤0.45). The influence of Se-doping on the composition and morphology of n-type Bi2Te3-xSex was studied by X-ray diffraction, scanning electron microscope and transmission electron microscope. Thermoelectric properties of the as-prepared bulk Bi2Te3-xSexnanocomposites were investigated in detail. Results showed that the grain became finer by the Se-doping. With increasing Se doping content, the electrical conductivity of bulk Bi2Te3-xSex increased firstly and then decreased. Se-doping effectively reduced the thermal conductivity and improved the Seebeck coefficient to some extent. Consequently, a maximum ZT value of 0.57 was obtained from bulk Bi2Te2.7Se0.3 at 475 K, which was increased by 159% as compared with pure bulk Bi2Te3.