Improving thermoelectric performance of p-type Ag-doped Mg2Si0.4Sn0.6 prepared by unique melt spinning method

Abstract

In our work, p-type Mg2−xAgxSi0.4Sn0.6 (x=0.00, 0.01, 0.02, 0.05, 0.07) compounds with single-phase are successfully synthesized via a home-made melt spinning (MS) system followed by spark plasma sintering (SPS). This unique process not only largely shortens the time of sample preparation compared with the traditional methods, but also successfully prevents the presence of MgO impurity phase. All samples are single-phase solid solutions with an anti-fluorite structure as identified by XRD. The thermoelectric properties of Mg2−xAgxSi0.4Sn0.6 compounds were measured from room temperature to 773K. The final results indicate that (1) Ag serves as effective holes donor and (2) the electrical conductivity rises rapidly and the thermal conductivity decreases with increasing Ag content until x=0.05. As a result, a peak dimensionless figure of merit ZT value of 0.45 at 690K is achieved when x=0.05. The enhanced thermoelectric performance coupled with the drastically reduced processing time will be of considerable significance to the commercial-scale production of Mg2X (X=Si, Ge, and Sn) thermoelectric material.