NaZn13-type La0.5Pr0.5(Fe 0.88Si0.12)13 exhibits an isotropic volume change associated with the thermal-induced first-order transition at the Curie temperature TC 186 K. The magnitude of the isotropic volume change at TC of La0.5Pr0.5(Fe0.88Si 0.12)13 is about 1.3 %, larger than that of La(Fe 0.88Si0.12)13. As a result, the enhancement in the local magnetic moment of Fe at TC is caused by the partial substitution of Pr. The volume change around TC of La 1-zPrz(Fe0.88Si0.12)13 is comparable in magnitude to that of La1-z,Ce2,(Fe 0.88Si0.12)13 having the same TC. Accordingly, the enhancement in the local magnetic moment of Fe at TC for La1-zPrz(Fe0.88Si0.12) 13 is closely related with the decrease of TC without the marked decrease of thermal stability of Fe moment.
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