Magnetic properties and magnetocaloric effect in La0.7Nd0.3Fe13-xSix compounds

The structural, magnetic and magnetocaloric properties in the cubic NaZn13-type La0.7Nd0.3Fe13-xSix compounds with x=1.2, 1.4, 1.6 and 1.8 are reported. All of the investigated samples are ferromagnetically ordered. The Fe saturation moment at 5 K is independent of Si concentration, having a value of 2.05 +/- 0.09 mu(B), which suggests a high degree of localization. The Curie temperatures increase almost linearly with the increase in silicon concentration. The large Delta S-M values obtained for samples with low Si content are mainly due to the first-order character of the transition at T-C. The field-induced transition above T-C causes an asymmetric broadening of the Delta S-M peak towards higher temperatures for higher applied fields. With increasing Si content, the first-order character of the transition at T-C is diminished, leading to lower Delta S-M values. The potential use of these materials in magnetic refrigeration is discussed. (C) 2012 Elsevier Inc. All rights reserved.