Insight into the Structural and Magnetic Properties of PrZnSi and NdZnSi Compounds Featuring Large Low-Temperature Magnetocaloric Effects

The magnetocaloric (MC) and magnetic phase transition (MPT) properties in various types of rare earth (RE)-based magnetic materials have been intensively investigated recently, which are aimed at developing suitable MC materials for low-temperature cooling applications and better elucidating their inherent physical properties. We herein provide a combined experimental and theoretical investigation into two new light RE-based magnetic materials, namely, PrZnSi and NdZnSi compounds, regarding their structural, magnetic, MPT, and low-temperature MC properties. Both of these compounds crystallize in an AlB2-type hexagonal structure with a symmetry of the crystallographic space group P6/mmm and reveal a typical second-order-type MPT with ordering temperatures (T-C) at approximately 13.5 and 18.5 K for PrZnSi and NdZnSi compounds, respectively. Moreover, they all exhibit large reversible low-temperature MC effects and remarkable performances, which are identified by the parameters of maximum magnetic entropy changes, relative cooling power, and temperature-averaged entropy change (temperature lift 5 K). The deduced values of these MC parameters under a magnetic field change of 0-7 T reach 16.3 J/kgK, 294.46 J/kg, and 15.79 J/kgK for PrZnSi and 15.4 J/kgK, 284.84 J/kg, and 14.95 J/kgK for NdZnSi, respectively, which are evidently better than those of most updated light RE-based magnetic materials with remarkable low-temperature MC performances, indicating that PrZnSi and NdZnSi compounds hold potentials for practical cooling applications.