Successive magnetic transitions and magnetocaloric effects in intermetallic compounds RE5Pt3 (RE = Dy, Ho)

The structure, low-temperature magnetic transition behaviors, and magnetocaloric properties of rare-earth-based binary compounds RE5Pt3 (RE = Dy, Ho) were studied. Both of the compounds crystallize in the Mn5Si3 hexagonal structure with a P63/mcm space group. With the decrease of temperature, the compounds undergo a phase transition from the paramagnetic (PM) state to the ferromagnetic (FM) state, followed by a spin reorientation. In the paramagnetic region, the reciprocal magnetic susceptibilities of RE5Pt3 obey the Curie -Weiss law. The effective paramagnetic magnetic moment values were determined to be 10.59 mu B/Dy3+ and 10.40 mu B/Ho3+, respectively, with the corresponding paramagnetic Curie temperatures of 30.0 K and 16.4 K. The maximum magnetic entropy changes (-Delta SM) of RE5Pt3 (RE = Dy, Ho) were calculated to be 8.2 J/kg K and 9.1 J/ kg K for a field change of 0-5 T. In addition, it is confirmed that the successive magnetic phase transition enlarges the magnetic entropy change and the working temperature region by Lorentz bimodal fitting. Evidently, the RE5Pt3 (RE = Dy, Ho) compounds with reversible MC effect are expected to have effective applications in the low-temperature range.