Structural and magnetic properties of Pr5Si3-xGex compounds

The crystal structures, magnetic properties and electronic structures of pseudo-binary compounds Pr5SixGe3-x were investigated. With the increase of the Ge content, structure of Pr5SixGe3-x gradually changes from the tetragonal Cr5B3-type to the hexagonal Mn5Si3-type. For the compounds with the tetragonal structure, the unit cell volumes as well as the magneto-crystalline anisotropy energy (MAE) increase with the Ge content, leading to the diminishing of the magnetization and the maximum magnetic entropy changes -ΔSM. As compared to the binary compound Pr5Si3, the intermetallic compounds with Ge doping show broader working temperature span and considerably large relative cooling power (213.9, and 184.8 J kg−1 at ΔH = 50 kOe for Pr5Si2.5Ge0.5 and Pr5Si2Ge, respectively). For the hexagonal compound Pr5Ge3, a large MAE and an easy magnetization direction close to c axis (polar angle θ ∼7°) were calculated, which is related to the macroscopic magnetic transition behavior at low temperature.