Enhanced thermoelectric performance of p-type ZrCoSb0.9Sn0.1 via Tellurium doping

Doping strategy has been shown as an effective paradigm in most of the thermoelectric materials for optimization of high ZT. Herein, we have synthesized several compositions of Te doped p-type ZrCoSb(0.9-x)Sn(0.1)Tex (0< x <0.08) Half-Heusler (HH) alloys employing arc melting followed by spark plasma sintering (SPS). X-ray Diffraction (XRD) analysis reveals the formation of single phase of MgAgAs type HH phase. Thermoelectric properties were measured from room temperature to 773 K. Interestingly, Te doping on Sb site in ZrCoSb0.9xSn0.1Tex leads to decrease of lattice thermal conductivity and a minimum lattice thermal conductivity similar to 1.98 WK(1)m(1) at 773 K for composition ZrCoSb0.9-xSn0.1Tex (x = 0.08) was optimized. The reduction in thermal conductivity is attributed to scattering of phonons by mass fluctuation and grain boundaries. In addition to this, significant improvement in power factor (similar to 16.89 mu WK(-2)cm(1a)t 773K) for ZrCoSb(0.9-x)Sn(0.1)T(e)x (x = 0.06) was observed to be optimized. The enhancement in power factor is mainly attributed due to increased Seebeck co-efficient manifested by reduction in effective hole carrier density occurred by Te substitution on Sb site. Thus, combination of reduced thermal conductivity and enhanced power factor obtained via Te substitution at Sb site leads to a high ZT similar to 0.53 for ZrCoSb0.9-xSn0.1Tex (x = 0.06). The present ZT similar to 0.53 optimized for ZrCoSb0.9xSn0.1Tex (x = 0.06) is 150% larger than that of un-doped ZrCoSb0.9Sn0.1 compound.

Automated summary

Doping with Te on the Sb site decreases the lattice thermal conductivity and increases the power factor of ZrCoSb0.9-xSn0.1Tex alloys, leading to a significant improvement in ZT value.