A Review of Boron-Rich Silicon Borides Basedon Thermodynamic Stability and Transport Properties of High-Temperature Thermoelectric Materials

Abstract

In this study, the performance of a boron-rich Si-B system containing ~ 2-25 mol% Si is reviewed as a high-temperature thermoelectric material. In this review, both thermodynamic stability and transport properties are evaluated to understand the high-temperature thermoelectric performance of the Si-B system. The thermodynamic properties, such as Gibbs energy and activity coefficient, of the Si-B system were calculated and compared to the literature data. Thermoelectric properties such as Seebeck coefficient, electrical conductivity, and thermal conductivity were reviewed for the Si-B system. It is found that the composition and processing techniques are critical for obtaining higher thermoelectrical properties and thus also true for the figure of merit ZT. The entropy (degree of randomness) of a system has a remarkable effect on ZT. The highest ZT obtained for this system is approximately 0.2 at 90% B (SiB 6 + SiB n ) containing SiB n phase, shows the lowest entropy (~32 J/mol∗K) in this system at 1100 K.