Magnetic properties and magnetic entropy changes of La_1-xPr_xFe_11.5Si_1.5 compounds with 0≤x≤ 0.5

Magnetic properties and magnetic entropy changes in LaFe_11.5Si_1.5 have been investigated by partially substituting Pr by La. It is found that La_1 - xPr_xFe_11.5Si_1.5 compounds remain cubic NaZn_13-type structures even when the Pr content is increased to 0.5, i.e. x = 0.5. Substitution of Pr for La leads to a reduction in both the crystal constant and the Curie temperature. A stepwise magnetic behaviour in the isothermal magnetization curves is observed, indicating that the characteristic of the itinerant electron metamagnetic (IEM) transition above T_C becomes more prominent with the Pr content increasing. As a result, the magnetic entropy change is remarkably enhanced from 23.0 to 29.4 J/kg\cdotK as the field changes from 0 to 5 T, with the value of x increasing from 0 to 0.5. It is more attractive that the magnetic entropy changes for all samples are shaped into high plateaus in a wide range of temperature, which is highly favourable for Ericsson-type magnetic refrigeration.