Large Magnetocaloric Effect of PrNi Compound at Liquid-Hydrogen Temperatures

In the work, polycrystalline PrNi compound was synthesized by the arc-melting method. The crystal structure is determined as a CrB-type orthorhombic structure (Space group Pnma). The Curie temperature (T-C) is determined to be 21.0 K according to the maximum absolute value of the first derivative of magnetization. The slope of the Arrott plots is positive around phase transition temperature, indicating the second-order phase transition (SOPT) characteristic. The magnetic entropy change (-Delta S-M) was calculated from the isothermal magnetization data based on Maxwell's relationship. The maximum value of -Delta S-M is calculated to be 7.3 and 13.0 J/kg center dot K for the magnetic field changes of 0-2 and 0-5 T, respectively. The large magnetocaloric effect (MCE) around 21.0 K with a SOPT feature indicates that PrNi is great potential in the application of magnetic refrigeration for hydrogen liquefaction.