Large entropy change derived from orbitally assisted three-centered two-electron σ bond formation in metallic Li0.33VS2

Abstract

We discuss herein the emergence of a large entropy change in metallic ${\mathrm{Li}}_{0.33}{\mathrm{VS}}_2$ derived from orbitally assisted loose $\sigma$ bond formation. Comprehensive structural studies based on synchrotron x-ray and neutron diffraction analyses clarify the fabrication of ribbon chains at 375 K, consisting of multiple three-centered two-electron $\sigma$ bonds based on the viewpoint of local chemical bonding. Although the metallic conductivity persists down to the lowest temperature measured, an exceptionally large entropy change as a metal, as much as $\mathrm{\Delta }S=6.6{\mathrm{J}\mathrm{mol}}^{-1}{\mathrm{K}}^{-1}$, appears at the transition. The emergence of a large entropy change in a metallic state may possibly lead to different functional materials, such as a heat-storage material with a rapid thermal response.