Synergetic effect of interface barrier and doping on the thermoelectric transport properties of tellurium
Energy filtering effect is helpful to decouple Seebeck coefficient and electric conductivity, and dopant is helpful for improving conductivity; in this work, synergetic function of both is supposed to enhance zT values of tellurium. In bulk Te and Sb 0.003 Te 0.997 , the Ni/Te heterojunction was built by electroless plating combined with spark plasma sintering. The Ni/Te interface barrier successfully decoupled the relationship between the Seebeck coefficient and the electrical resistivity. The Seebeck coefficient and resistivity of Ni/Te samples increased by 37.9% and decreased by 28.1%, respectively. Meanwhile, the thermal conductivity of the Ni/Te samples decreased by 25.8% (T = 300 K), and the zT value was increased by 36.4% compared to the pure Te sample. Consequently, a peak zT of 0.96 at 550 K is achieved in 18wt %Ni/Sb 0.003 Te 0.997 sample,which is 50% higher than Sb 0.003 Te 0.997 samples. This work indicates that electroless plating combined with spark plasma sintering is an effective method to construct heterojunction in bulk materials. This method should be widely applicable to various materials for achieving better thermoelectric properties.
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