Barocaloric materials are characterized by strong, reversible thermic responses to changes in pressure.
Many involve solid-to-solid phase changes from disordered to ordered and rigid under increased pressure, releasing heat.
[1] One barocaloric material processes heat without a phase change: natural rubber.
[3] The hybrid organic–inorganic layered perovskite (CH3–(CH2)n−1–NH3)2MnCl4 (n = 9,10), shows reversible barocaloric entropy change of ΔSr ~ 218, 230 J kg−1 K−1 at 0.08 GPa at 294-311.5 K (transition temperature).
[5] A prototype air conditioner was made from a metal tube filled with a metal-halide perovskite (the refrigerant) and water or oil (heat/pressure transport material).
Neutron scattering characterizations of crystal structures/atomic dynamics show that reorientation-vibration coupling is responsible for the pressure sensitivity.