Homogeneity of Curie Temperature in La (Fe, Si)$_{13}$ Compounds by Co and C Doping

The microstructure and magnetic properties for LaFe
_10.85
Co
_0.65
Si
_1.5
C
_0.2
, LaFe
_11.5
Si
_1.5
C
_0.2
and LaFe
_10.85
Co
_0.65
Si
_1.5
compounds were investigated. The ingots were prepared by 5 kilogram Vacuum Induction Melting Furnace. Then LaFe
_10.85
Co
_0.65
Si
_1.5
C
_0.2
and LaFe
_11.5
Si
_1.5
C
_0.2
thin strips were prepared by the strip-casting process. The DSC measurement shows that the maximum latent heat of LaFe
_11.5
Si
_1.5
C
_0.2
thin strips has been obtained after annealing at 1353 K for 12 h, longer time annealing seems to be no good for latent heat. Substitute Co for Fe could cause inhomogeneous distribution of Curie temperature (T
_C
) in the bulk ingots, but the inhomogeneity can be improved by preparing the strip from the ingot. Under magnetic field changes of 0-1.5 T, the magnetic entropy change near the Curie temperature was about -11.1 J/kg· K and -4.0 J/kg· K for LaFe
_11.5
Si
_1.5
C
_0.2
and LaFe
_10.85
Co
_0.65
Si
_1.5
C
_0.2
, respectively.