Development of an Mg2Si Unileg Thermoelectric Module Using Durable Sb-Doped Mg2Si Legs

Mg₂Si unileg structure thermoelectric (TE) modules, which are composed only of n-type Mg₂Si legs, were fabricated using Sb-doped Mg₂Si. The Mg₂Si TE legs used in our module were fabricated by a plasma-activated sintering method using material produced from molten commercial doped polycrystalline Mg₂Si, and, at the same time, nickel electrodes were formed on the Mg₂Si using a monobloc plasma-activated sintering technique. The source material used for our legs has a ZT value of 0.77 at 862 K. The TE modules, which have dimensions of 21 mm × 30 mm × 16 mm, were composed of ten legs that were connected in series electrically using nickel terminals, and the dimensions of a single leg were 4.0 mm  × 4.0 mm × 10 mm. From evaluations of the measured output characteristics of the modules, it appeared that the electrical resistance of the wiring that is used to connect each leg considerably affects the power output of the unileg module. Thus, we attempted to reduce the wiring resistance of the module and fabricated a module using copper terminals. The observed values of the open-circuit voltage and output power of the Sb-doped Mg₂Si unileg module were 496 mV and 1211 mW at ΔT = 531 K (hot side: 873 K; cool side: 342 K).