2010 Volume 51 Issue 5 Pages 868-871
The single-phase of p-type Mg2Si0.25Sn0.75 with Li and Ag double doping were prepared by the liquid-solid reaction and hot-pressing methods. All samples thus obtained were identified by XRD as single-phase solid solutions with an anti-fluorite structure. The effects of Li and Ag double doping on thermoelectric performance were investigated at temperature differences (ΔT) of 0 to 500 K. The thermoelectromotive force (E) of the Li-25000 ppm single-doped sample was determined to be 88 mV at ΔT=500 K. For the Li-20000 ppm and Ag-5000 ppm double-doped sample, the E value became larger (92 mV) after Ag substitution. A maximum E value of 97 mV was obtained for the Ag-25000 ppm single-doped sample and the Li-5000 ppm and Ag-20000 ppm double-doped sample. Mean resistivity (rm) at ΔT=500 K decreased by double doping and showed a minimum value of 2.94×10−5 Ωm for the Li-5000 ppm and Ag-20000 ppm double-doped sample. The maximum effective power (P=E2⁄4rm) increased with ΔT. The P values of single-doped samples at ΔT=500 K were 38 Wm−1 for Li single-doped and 72 Wm−1 for Ag single-doped samples. P for the Li-20000 ppm and Ag-5000 ppm double-doped sample was 64 Wm−1, which was an improvement of about 90% compared with the Li single-doped sample. The maximum value of P at ΔT=500 K was 80 Wm−1 for the Li-5000 ppm and Ag-20000 ppm double-doped sample, which was an improvement of about 10% compared with the Ag single-doped sample.
