Thermal Conductivity Switching in Sm1-xGdxS over a Broad Temperature Window via a Pressure-induced, Thermally Revertible Hysteretic Phase Transition

Abstract

Solid-state materials with actively tunable thermal conductivities hold great interest for next-generation thermal management technologies, yet there is a critical need for materials that can be switched between high and low thermal conductivities over a large temperature window using different on and off triggers. Here, we establish that Sm_1-xGd_xS alloys, which undergo a pressure-induced, hysteretic, rock salt-to-rock salt metal-insulator transition, can be repeatedly cycled between high and low thermal conductivity states from 200 to 550 K due to differences in electronic contributions in thermal conductivity. Intermediate stoichiometries (0.08 ≤ x ≤ 0.14) transform from a mixed black/gold phase at ambient pressure to a metallic gold phase upon uniaxial compression at 1 GPa, leading to a 2-fold increase in thermal conductivity. The gold phase rapidly reverts to the equilibrium low thermal conductivity phase upon exposure to temperatures above 573 K. These findings establish that Sm_1-xGd_xS alloys have exceptional promise for thermal switching and management applications.