Abstract
We report an ethanol‐mediated surfactant‐free solvothermal synthesis of phase‐pure Pnmm FeSb~2~ nanocrystals with an average size of 40 nm. The capping free growth of the nanocrystals resulted in the formation of inherent orthorhombic shapes. The nanocrystals were densified by spark plasma sintering to prepare a polycrystalline bulk material that consisted of 40–200 nm FeSb~2~ nanocrystal domains (nanocomposite). Low‐temperature Seebeck coefficient, resisitivity, and thermal conductivity were measured on parallelopipeds cut from the densified specimen and compared to bulk FeSb~2~ prepared by a solid‐state synthesis process. The FeSb~2~ nanocomposite showed a large reduction in lattice thermal conductivity relative to the bulk due to significant grain‐boundary phonon scattering. If one notes that the solution‐phase synthesis of Pnnm FeSb~2~ nanocrystals is accounted here for the first time and the low‐temperature thermoelectric properties indicates a significant reduction in lattice thermal conductivity for this material, this work represents an important step towards optimizing thermoelectric properties for cooling applications.