Colossal barocaloric effects in the complex hydride Li 2 B 12 H 12

Traditional refrigeration technologies based on compression cycles of greenhouse gases pose serious threats to the environment and cannot be downscaled to electronic device dimensions. Solid-state cooling exploits the thermal response of caloric materials to changes in the applied external fields (i.e., magnetic, electric and/or mechanical stress) and represents a promising alternative to current refrigeration methods. However, most of the caloric materials known to date present relatively small adiabatic temperature changes (|¿T|~1 to 10 K) and/or limiting irreversibility issues resulting from significant phase-transition hysteresis. Here, we predict by using molecular dynamics simulations the existence of colossal barocaloric effects induced by pressure (isothermal entropy changes of |¿S|~100 J K-1 kg-1) in the energy material Li2B12H12. Specifically, we estimate |¿S|=367 J K-1 kg-1 and |¿T|=43 K for a small pressure shift of P = 0.1 GPa at T=480 K. The disclosed colossal barocaloric effects are originated by a fairly reversible order–disorder phase transformation involving coexistence of Li+ diffusion and (BH)-212 reorientational motion at high temperatures.Peer ReviewedPostprint (published version