Low-field magnetocaloric effect in Pr/sub 1-x/Pb/sub x/MnO/sub 3/ (0.1 /spl les/ x /spl les/ 0.5) perovskites

The discovery of large low-field magnetocaloric effects (MCE) in polycrystalline Pr/sub 1-x/Pb/sub x/MnO/sub 3/ (0.1 /spl les/ x /spl les/ 0.5) is reported, which were prepared by the conventional ceramic technique. Upon 13.5 kOe applied field, the magnetic entropy change (/spl Delta/S/sub M/) reaches values of 3.91, 3.68 and 3.34 J/kg K for x = 0.1, 0.4 and 0.5 compositions, respectively, and which are larger than that of the well-known magnetic refrigerant material of Gd, /spl Delta/S/sub M/ = 3.32 J/kg K. These new perovskites having large /spl Delta/S/sub M/ caused by a low applied magnetic field that can be generated by permanent magnets are excellent candidates, for working materials in magnetic refrigeration in a temperature range of 150 - 270 K. Furthermore, the peak of /spl Delta/S/sub M/ locates at a temperature that is higher than its Curie temperature and it is considerably shifted to a higher value when the magnetic field is increased. This observation opens a new window to explore the magnetic refrigeration in a high temperature regime.