The refrigerant capacity in spin-crossover materials: Application to [Fe(phen)2(NCS)2]

Abstract The next-generation of refrigerant materials should be based on solid materials with big entropy-driven conversion when submitted to an external stimulus change. We report the refrigerant capacity (RC = 2950 J kg −1 , upon pressure change of ΔP = 1 kbar) in one of the most known and investigated spin-crossover material [Fe(phen) 2 (NCS) 2 ]. Our indirect obtained experimental data for the isothermal entropy change (ΔS T  = 78 Jkg −1 K −1 ) and the adiabatic temperature change (ΔT ad  = 11 K) for ΔP = 1 kbar, agree with our theoretical calculations. From comparison between the thermodynamic and microscopic entropy descriptions, the origin of the barocaloric effect was ascribed to the pressure phonons activation in spin-crossover materials. Besides, a proper refrigeration thermodynamic cycle (Ericsson cycle) was quantitatively used for showing the refrigeration capacity of [Fe(phen) 2 (NCS) 2 ].