Magnetocaloric effect of the LaFe11.2Co0.7Si1.1 modified by partial substitution of La by Pr or Ho

Publication date: 5 September 2017
Source:Materials & Design, Volume 129
Author(s): Piotr Gębara, Jozef Kovac
The aim of present paper was to study the structure and magnetocaloric effect in La0.9X0.1Fe11.2Co0.7Si1.1 (where X=Pr, Ho) alloys. The XRD investigation revealed a coexistence between the expected La(Fe,Si)13-type phase and minor fraction of α-Fe(Co,Si) in both samples. Moreover, a significant decrease in the lattice parameter of the La(Fe,Si)13 phase for sample doped by Ho, compared to specimen modified by Pr, was detected. The values of the Curie temperature reach 259 and 263K for the Pr and Ho doped sample, respectively. The calculated values of magnetic entropy change equaled 15.73 and 10.91J/(kg K) under the change of external magnetic field μ0ΔH=5T for the La0.9Pr0.1Fe11.2Co0.7Si1.1 and La0.9Ho0.1Fe11.2Co0.7Si1.1 alloys, respectively. Based on the field dependence of magnetic entropy change (ΔSM=C·(Bmax)ⁿ), the exponent n has been calculated and at the Curie point its values equaled 0.64 and 0.65 determined for La0.9Pr0.1Fe11.2Co0.7Si1.1 and La0.9Ho0.1Fe11.2Co0.7Si1.1 alloys, respectively. These values correspond well with theoretical predictions.

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