Growth and Magnetocaloric Properties of Co(NH4)2(SO4)2·6H2O Crystal

Co(NH4)2(SO4)2·6H2O single crystal was grown via slow solvent evaporation at room temperature. The magnetic and magnetocaloric properties were investigated. The results show that Co(NH4)2(SO4)2·6H2O exhibits paramagnetic behavior across 2–300 K. The maximum magnetic entropy change (−ΔSM) of 13.90 J kg−1 K−1 under conditions of 2 K and μ0ΔH = 5 T approaches the theoretical value of 14.58 J kg−1 K−1. In addition, the variation of −ΔSM with temperature is relatively flat, suggesting a wide working temperature range for magnetic refrigeration, which provides the possibility for the application of Co2+-based compounds in the field of low-temperature magnetic refrigeration.