Thermoelectric Performance of Ca2Si Synthesized by High-Temperature Melting

Abstract

Ca2Si was successfully synthesized via a high-temperature melting furnace and a spark plasma sintering process, allowing its thermoelectric properties to be studied. High-temperature melting furnaces were utilized to inhibit the volatilization of Ca elements during the preparation stage, ensuring the production of high-purity Ca2Si. The resistivity of Ca2Si increased gradually with rising temperature and reached 12 mΩ·cm at 873 K, demonstrating semi-metallic characteristics. In the temperature range of 323 K–873 K, Ca2Si displayed relatively low total thermal conductivity, from 1.1 to 1.7 W·m−1·K−1. Nevertheless, Ca2Si attained a maximum thermoelectric figure of merit (ZT) of 0.1 due to the atypical behavior and electrical properties of semiconductors. In contrast, Mg2Si achieved a ZT value of 0.32 at 873 K, owing to its exceptional Seebeck coefficient.