Study on thermoelectric performance by Na doping in nanostructured Mg$_{1-x}$Na$_{x}$Ag$_{0.97}$Sb$_{0.99}$

MgAg$_{0.97}$Sb$_{0.99}$ was found to be potentially a new class of thermoelectric materials with \textit{ZT} values above 1 in the temperature from 100 to 300 $^{\circ}$C. In this report, we systematically studied the effect of Na doping in Mg, Mg$_{1-x}$Na$_{x}$Ag$_{0.97}$Sb$_{0.99}$, on the thermoelectric properties and found Na was effective to increase the carrier concentration and power factor, especially below 180 $^{\circ}$C, which led to higher \textit{ZT} values, a better self-compatibility factor, and ultimately a higher output power at the optimal Na concentration of x $=$ 0.005-0.0075.