Thermoelectric Behavior of Sb- and Al-Doped n-Type Mg2Si Device Under Large Temperature Differences

The thermoelectric (TE) characteristics of Sb- and Al-doped n-type Mg2Si elemental devices fabricated using material produced from molten commercial doped polycrystalline Mg2Si were examined. The TE devices were prepared using a plasma-activated sintering (PAS) technique. To complete the devices, Ni electrodes were fabricated on each end of them during the sintering process. To realize durable devices for large temperature differences, thermodynamically stable Sb-doped Mg2Si (Sb-Mg2Si) was exposed to the higher temperature and Al-doped Mg2Si (Al-Mg2Si) was exposed to the cooler temperature. The devices consisted of segments of Sb-Mg2Si and Al-Mg2Si with sizes in the following ratios: Sb-Mg2Si:Al-Mg2Si = 4:1, 1:1, and 1:4. A device specimen composed solely of Sb-Mg2Si showed no notable deterioration even after aging for 1000 h, while some segmented specimens, such as those with Sb-Mg2Si:Al-Mg2Si = 1:1 and 1:4, suffered from a considerable drop in output current over the large Delta T range. The observed power generated by specimens with Sb-Mg2Si:Al-Mg2Si = 1:1 and 1:4 and sizes of 2 mm x 2 mm x 10 mm were 50.7 mW and 49.5 mW, respectively, with higher and lower temperatures of 873 K and 373 K, respectively. For the sample composed solely of Sb-Mg2Si, a power of 55 mW was demonstrated. An aging test for up to 1000 h for the same Delta T range indicated drops in output power of between similar to 3% and 20%.