Colossal barocaloric effects in the complex hydride Li2B12H12

K Sau and T Ikeshoji and S Takagi and SI Orimo and D Errandonea and DW Chu and C Cazorla, SCIENTIFIC REPORTS, 11, 11915 (2021).

DOI: 10.1038/s41598-021-91123-4

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 (vertical bar Delta T vertical bar similar to 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 vertical bar Delta S vertical bar similar to 100 J K-1 kg(-1)) in the energy material Li2B12H12. Specifically, we estimate vertical bar Delta S vertical bar = 367 J K-1 kg(-1) and vertical bar Delta T vertical bar = 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)(12)(-2) reorientational motion at high temperatures.

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