Large barocaloric effect in spin-crossover complex [CrI2(depe)2]

Abstract

Recently, spin-crossover compounds were pointed out as strong candidates for working as refrigerant materials due to their huge barocaloric effect. In this work, we report the giant isothermal entropy change (ΔST) and adiabatic temperature change (ΔTad) upon moderated pressure variation in the spin-crossover complex [CrI2(depe)2], where depe = 1,2-bis(diethylphosphino)ethane. This complex was investigated considering three main contributions for total entropy: configurational, magnetic, and phonon entropies, which were simulated using proper microscopic parameters. The high values of ΔST = 40 J kg−1 K−1 and ΔTad = 10.6 K for ΔP = 2 kbar were obtained around low ↔ high spin phase transition temperature (T1/2). Besides, due to the large barocaloric shift parameters (δT1/2/δP ∼ 52 K/kbar), a giant refrigerant capacity (RC = 3583 J kg−1) was established for [CrI2(depe)2].