Synthesis and thermoelectric properties of Zn4Sb3/Bi0.5Sb1.5Te3 bulk nanocomposites

The bulk nanocomposites f(Zn4Sb3)/Bi0.5Sb1.5Te3 (f = 0, 5, 10 and 15 vol.%) were prepared, and their thermoelectric properties were investigated at temperatures from 300 to 650 K. The results of X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) showed that the nanometer-sized Zn4Sb3 particles were dispersed homogeneously in Bi0.5Sb1.5Te3 matrix. Transport property measurements indicated that the resistivity and Seebeck coefficient of the composite samples f(Zn4Sb3)/Bi0.5Sb1.5Te3 (f = 0, 5, 10 and 15 vol.%) decreased with increasing Zn4Sb3 content due to the increase in carrier concentration. Experiments also showed that thermal conductivity of f(Zn4Sb3)/Bi0.5Sb1.5Te3 decreased monotonically with increasing f owing to enhanced phonon scattering by the dispersed Zn4Sb3 nanoparticles and the phase boundaries in the matrix. Among the samples studied, 15 vol.% (Zn4Sb3)/Bi0.5Sb1.5Te3 exhibited the largest power factor (25 μW/cm K2 at ∼300 K) that was 2.5 times larger than that of Bi0.5Sb1.5Te3; correspondingly, its figure of merit (ZT = 0.6 at ∼300 K) was about three times larger than that of Bi0.5Sb1.5Te3, indicating that the thermoelectric properties of Bi0.5Sb1.5Te3 can be enhanced effectively by the dispersion of nanometer-sized Zn4Sb3.