Prediction of large barocaloric effects in thermoelectric superionic materials

Abstract

We predict the existence of large barocaloric effects above room temperature in the thermoelectric fast-ion conductor Cu${}_2$Se by using classical molecular dynamics simulations and first-principles computational methods. A hydrostatic pressure of $1$ GPa induces large isothermal entropy changes of $|\Delta S|\sim 15$-$45$ Jkg${}^{-1}$K${}^{-1}$ and adiabatic temperature shifts of $|\Delta T|\sim 10$ K in the temperature interval $400\le T\le 700$ K. Structural phase transitions are absent in the analysed thermodynamic range. The causes of such large barocaloric effects are significant $P$-induced variations on the ionic conductivity of Cu${}_2$Se and the inherently high anharmonicity of the material. Uniaxial stresses of the same magnitude, either compressive or tensile, produce comparatively much smaller caloric effects, namely, $|\Delta S|\sim 1$ Jkg${}^{-1}$K${}^{-1}$ and $|\Delta T|\sim 0.1$ K, due to practically null influence on the ionic diffusivity of Cu${}_2$Se. Our simulation work shows that thermoelectric compounds presenting high ionic disorder, like copper and silver-based chalcogenides, may render large mechanocaloric effects and thus are promising materials for engineering solid-state cooling applications that do not require the application of electric fields.

10 pages, 5 figures, 1 table

References in corpus (4)

• Colossal barocaloric effects near room temperature in plastic crystals of neopentylglycol
• Superionicity and Polymorphism in Calcium Fluoride at High Pressure
• Giant Direct and Inverse Electrocaloric Effects in Multiferroic Thin Films
• Comment on "High-pressure phases of group-II difluorides: Polymorphism and superionicity"