Magnetism and magnetic entropy change of LaFe11.6Si1.4Cx (x=0-0.6) interstitial compounds

Chemically stable LaFe11.6Si1.4Cx (x=0-0.6) interstitial compounds were prepared. The Curie temperatures increases from 195 to 250 K with an increase in X from 0 to 0.6 due to obvious lattice expansion. The maximal magnetic entropy changes \DeltaS\ with a change in magnetic field of 0-5 T, are 24.8, 24.2, 18.8 and 12.1 J/kg K for x=0, 0.2, 0.4, and 0.6, respectively, notably exceeding that of Gd (\DeltaS\similar to9.8 J/kg K at T-C=293 K). The magnetic transition varies from first order to second order with an increase in carbon concentration, which has a decisive influence on \DeltaS\. The large \DeltaS\, chemical stability, and low cost make LaFe11.4Si1.6Cx a promising candidate as a magnetic refrigerant in the corresponding temperature ranges. (C) 2003 American Institute of Physics.