Improved thermoelectric performance in p-type Bi0.48Sb1.52Te3 bulk material by adding MnSb2Se4

Bismuth telluride (Bi2Te3) based alloys, such as p-type Bi0.5Sb1.5Te3, have been leading candidates for near room temperature thermoelectric applications. In this study, Bi0.48Sb1.52Te3 bulk materials with MnSb2Se4 were prepared using high-energy ball milling and spark plasma sintering (SPS) process. The addition of MnSb2Se4 to Bi0.48Sb1.52Te3 increased the hole concentration while slightly decreasing the Seebeck coefficient, thus optimising the electrical transport properties of the bulk material. In addition, the second phases of MnSb2Se4 and Bi0.48Sb1.52Te3 were observed in the Bi0.48Sb1.52Te3 matrix. The nanoparticles in the semi-coherent second phase of MnSb2Se4 behaved as scattering centres for phonons, yielding a reduction in the lattice thermal conductivity. Substantial enhancement of the figure of merit, ZT, has been achieved for Bi0.48Sb1.52Te3 by adding an Mn0.8Cu0.2Sb2Se4 (2 mol%) sample, for a wide range of temperatures, with a peak value of 1.43 at 375 K, corresponding to similar to 40% improvement over its Bi0.48Sb1.52Te3 counterpart. Such enhancement of the thermoelectric (TE) performance of p-type Bi2Te3 based materials is believed to be advantageous for practical applications.