Entropy changes accompanying the magnetic phase transitions in low Si-doped Ce 2Fe 17−xSi x Alloy

Abstract

A summary of the results of ac susceptibility and isothermal magnetization measurements on polycrystalline samples of Ce 2Fe 17− x Si x with nominal composition of x=0.0, 0.1, 0.2 and 1.0 is presented. These data reveal that the substitution of small amounts of Si for Fe produce a significant increase in temperature at which ferromagnetism appears, to the extent that, at x=1, characteristics of the anti ferromagnetic to paramagnetic transition (at temperature T N) have disappeared completely. The nature of the various magnetic phase transitions — identified through the use of Arrott plots — and the accompanying magnetic entropy change, Δ Sm, are both affected significantly by small amounts of Si substitution. In particular, while the peak entropy change is modest (occurring at x=0.1), the temperature interval over which a substantial entropy change occures is significant, approaching 150 K, an important criterion for improving the overall effectiveness of such materials for magnetic refrigeration.