Influences of Nanostructuring and Densification Processes on the Lattice Thermal Conductivity of n -Type Indium Antimonide

Indium antimonide (InSb), an n-type narrow-band gap semiconductor, has attracted considerable interest in intermediate-temperature thermoelectric (TE) applications due to its excellent electronic transport properties; however, its relatively high lattice thermal conductivity limits its TE performance. Here, we explore the effects of mechanical milling and densification techniques on the structural, vibrational, thermoelectric, and mechanical properties of InSb prepared by the solid-state melting route, then ball-milled and densified via resistive hot-press (RHP) and induction-assisted hot-press (IHP). Phase identification and microstructural analyses of InSb have been examined by powder X-ray diffraction and electron probe microanalysis. Mechanical milling drastically reduces the crystallite size, suppresses the lattice thermal conductivity (κlat) through enhanced phonon scattering, and decreases electrical conductivity due to reduced carrier mobility. Further, the milled samples densified by RHP and IHP have shown ultralow κlat values of ∼3.46 and ∼4.69 W m–1 K–1 at 300 K, respectively, illustrating reductions of ∼50% and ∼47% compared to bulk RHP and IHP samples. The maximum zT of ∼0.38 at 723 K was obtained for bulk RHP, along with a high mechanical hardness of 2.14 GPa, implying that InSb is a potential n-type candidate for intermediate-temperature TE applications.