Abstract
Solid-state refrigeration which is environmentally benign has attracted considerable attention. Mechanocaloric (mC) materials, in which the phase transitions can be induced by mechanical stresses, represent one of the most promising types of solid-state caloric materials. Herein, we have developed a thermodynamic phenomenological model and predicted extraordinarily large elastocaloric (eC) strengths for the (111)-oriented metal-free perovskite ferroelectric [MDABCO](NH4)I3 thin-films. The predicted room temperature isothermal eC ΔSeC/Δσ (eC entropy change under unit stress change) and adiabatic eC ΔTeC/Δσ (eC temperature change under unit stress change) for [MDABCO](NH4)I3 are −60.0 J K−1 kg−1 GPa−1 and 17.9 K GPa−1, respectively, which are 20 times higher than the traditional ferroelectric oxides such as BaTiO3 thin films. We have also demonstrated that the eC performance can be improved by reducing the Young’s modulus or enhancing the thermal expansion coefficient (which could be realized through chemical doping, etc.). We expect these discoveries to spur further interest in the potential applications of metal-free organic ferroelectrics materials towards next-generation eC refrigeration devices.
Highlights
Solid-state refrigeration has attracted considerable attention due to its potential applications in small-scale cooling technology[1,2,3].There are several physical effects that can be utilized for solidstate refrigeration, such as magnetocaloric (MC)[4,5], electrocaloric (EC)[6,7,8,9], and mechanocaloric effects[10,11]
We first calculate the analytical equilibrium polarization for the (111)-oriented [MDABCO](NH4)I3 thin film under different in-plane misfit strains and out-of-plane stresses at room temperature
We further identify several intrinsic physical properties, namely the elastic compliance sij, thermal expansion coefficient βl on the eC effects of the metal-free npj Computational Materials (2021) 132
Summary
Solid-state refrigeration has attracted considerable attention due to its potential applications in small-scale cooling technology[1,2,3].There are several physical effects that can be utilized for solidstate refrigeration, such as magnetocaloric (MC)[4,5], electrocaloric (EC)[6,7,8,9], and mechanocaloric (mC) effects[10,11]. Solid-state refrigeration has attracted considerable attention due to its potential applications in small-scale cooling technology[1,2,3]. In MC and EC effects, a temperature change is induced by applying a magnetic field and electric field, respectively. The MC and EC strengths for typical ferromagnetic/ferroelectric materials are relatively small. The EC strengths for prototype ferroelectrics such as PbZr0.95Ti0.05O312 and fluorinated polymers[13] thin films are less than 1.0 K m MV−1. To achieve a large temperature change, a strong magnetic/electric field is required, which is normally provided by a huge auxiliary device, limiting the practical applications of the MC/EC materials in cooling devices[9,14,15]
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