Magnetocaloric effects in the La(Fe,Si)_(13) intermetallics doped by different elements

摘要

The magnetocaloric effects (MCEs) of LaFe_(13-x)Si_x. compounds doped by magnetic rare earths (R-Ce, Pr, and Nd) and transition metal (Co) are analyzed. It is found that varying the contents of R and Fe produces similar effects on the MCE, both of which cause a rapid decrease in AS with the increase in T_C. The DELTA S-T_C relations thus obtained coincide with each other fairly well, which indicates the equivalence of substituting R for La and Fe for Si. In contrast, partially replacing Fe by Co leads to a slow decrease in DELTA S with T_C. It is therefore a promising approach to maintain a large DELTA S up to high temperatures. As a comparison with these element-doping compounds, the MCEs of hydrides are also discussed. Although interstitial hydrogen can also keep up a large DELTA S to high temperatures, the corresponding hydrides are unfortunately unstable above 150 deg C. Based on these analyses, the potential refrigerants made of LaFe_(13-x)Si_x are proposed to have as low as possible Si content (or high R content) and proper Co content simultaneously.