Are Solid Solutions Better in FeNbSb-Based Thermoelectrics?

Forming solid solutions, due to its universal applicability, has been the most effective strategy for improving the performance of a wide variety of thermoelectric materials. Taking p-type FeNb1-xVxSb solid solutions as an example, here it is shown that the formation of solid solutions cannot always improve the thermoelectric performance. The peak zT and thermoelectric quality factor of p-type FeNb1-xVxSb decrease with increasing V content, remarkably different from other thermoelectric systems. The present results demonstrate that comprehensive understanding of the multiple effects of forming solid solutions is important for developing high-performance thermoelectrics.