Fig. 5.

a SEM image of the SnTe nanoparticles synthesized by microwave hydrothermal method. b SEM image of the dense specimen from the 165 nm nanoparticles. c Proposed electrical transporting mechanism of the dense samples sintered from the 165 nm, 550 nm nanoparticles (NPs), 8.2 μm microparticles (MPs), and mechanically alloyed (MA) powder. d Hole mobility, carrier concentration and the ratio of m_x*/m₀* as function of the decreased grain sizes. e TEM image of 40 nm FeSb₂ nanocrystals prepared by solvothermal method. f κ_L of the densified FeSb₂ nanocrystals (solid circle) and bulk FeSb₂ (open circle). The line of 1/T dependence (solid line) is indicative of phonon–phonon scattering. The inset shows an SEM image of a fractured surface of the densified FeSb₂ specimen. Adapted with permission from Refs. [91–93]