Magnetic-entropy change in Mn/sub 1.1/Fe/sub 0.9/P/sub 1-x/Ge/sub x/ compounds

The magnetic and magnetocaloric properties of Mn/sub 1.1/Fe/sub 0.9/p/sub 1-x/Ge/sub x/ compounds with x=0.20,0.22,0.23,0.26, and 0.30 have been investigated. In the composition range x from 0.20 to 0.30, the compounds crystallize in the Fe/sub 2/P-type hexagonal structure. The Curie temperature of the compounds strongly increases with increasing Ge contents. A history dependence of the magnetic phase transition is observed in this compound system. The optimum composition range and the temperature range of the Mn/sub 1.1/ Fe/sub 0.9/P/sub 1-x/Ge/sub x/ compounds for magnetic refrigeration applications have been determined. In the composition range x from 0.20 to 0.23, the compounds exhibit large magnetic-entropy change in a low magnetic field.