Realizing p-type Mg2Sn Thermoelectrics via Ga-Doping and Point Defect Engineering

Mg2Sn is a promising middle-temperature thermoelectric material consisting of earth-abundant, low-cost, and nontoxic elements. To obtain p-type Mg2Sn, a series of Mg2Sn1-xGax (x = 0, 0.005, 0.01, 0.02, and 0.03) ingots were synthesized by melting them under an Ar atmosphere. It was found that the ingots with x <= 0.02 were single crystals with Mg vacancies (V-Mg) as point defects. Ga doping increased chemical pressure, leading to an increase in the V-Mg fraction, and it also introduced hole carriers in Mg2Sn, which changed its conduction type from n-type to p-type. A maximum zT value of 0.18 at 450 K was obtained for p-type Mg2Sn0.98Ga0.02 single crystals, which had a lower total thermal conductivity than some other p-type Mg2Sn-based polycrystals.

Automated summary

The addition of Ga as a dopant in Mg2Sn can change its conduction type from n-type to p-type, leading to an increase in the magnesium vacancy fraction and the introduction of hole carriers. This doping strategy results in a lower total thermal conductivity at a certain concentration, contributing to the improvement of thermoelectric material performance.