Li₃Sb₇Se₁₂: A Pavonite Homologue with Ultralow Thermal Conductivity

Lithium-containing semiconductors have applications in solid-state batteries, thermoelectrics, and neutron detectors. Li 3 Sb 7 Se 12 is a new ternary semiconductor isostructural to the mineral benjaminite (Ag 3 Sb 7 S 12 ) crystallizing in monoclinic space group C 2/ m . Benjaminite belongs to the pavonite mineral family with the general formula M n +1 (Bi/Sb) 2 Q n +5 ( n = 0–8), where n is the octahedral building block length consisting of face-sharing octahedra. Li 3 Sb 7 Se 12 belongs to n = 7, and it differs from benjaminite by exhibiting occupancy disorder between Li + and Sb 3+ atoms. It exhibits exceptionally low lattice thermal conductivities of 0.53–0.37 W m –1 K –1 in the temperature range 300–873 K and is a p -type semiconductor. Chemical bonding analysis using DFT calculations indicates that hierarchical bonding and the distorted coordination environment of antimony play a prominent role in its heat transport properties, leading to ultralow lattice thermal conductivity, while selenium dominates the electronic structure near the bandgap.