Colossal barocaloric effects in the complex hydride Li₂B₁₂H₁₂

2020/08/17 by Sau, Kartik, Ikeshoji, Tamio, Takagi, Shigeyuki +4
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)

paper · doi:10.48550/arxiv.2008.07102

Abstract

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 external fields and represents a promising alternative to current refrigeration methods. However, most of the caloric materials known to date present relatively small adiabatic temperature changes (|ΔT| ∼ 1 K) and/or limiting irreversibility issues resulting from significant phase-transition hysteresis. Here, we predict the existence of colossal barocaloric effects (isothermal entropy changes of |ΔS| ∼ 100 JK^-1kg^-1) in the energy material Li₂B₁₂H₁₂ by means of molecular dynamics simulations. Specifically, we estimate |ΔS| = 387 JK^-1kg^-1 and |ΔT| = 26 K for an applied pressure of P = 0.4 GPa at T = 475 K. The disclosed colossal barocaloric effects are originated by an order-disorder phase transformation that exhibits a fair degree of reversibility and involves coexisting Li⁺ diffusion and (BH)₁₂^-2 reorientational motion at high temperatures.

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