Effect of Pr and Co substitution on magnetic properties and magnetic entropy changes in LaFe13-xSix compounds

Effect of Pr and Co substitution on magnetic properties and magnetic entropy changes in the cubic NaZn13-type compound LaFe11.2Si1.8 has been experimentally investigated. Replacing 30 at.% La with Pr leads to a decrease of Curie temperature from 216 to 203 K, and drives the magnetic transition from second-order to first-order. As a result, magnetic entropy change, under a field change of 0-5 T, increases from 13.7 to 19.4 J/kg K. Substitution of Co for Fe in La07Pr0.3Fe11.2Si1.8 can adjust T-C to around room temperature. A magnetic entropy change of 9.3 J/kg K at T-C = 290 K for a field change from 0 to 5 T is obtained in La07Pr0.3Fe10.4Co0.8Si1.8. A reversible variation of magnetization with temperature and magnetic field is observed in the present compound, which is highly desired by the magnetic refrigeration application. (c) 2007 Elsevier B.V. All rights reserved.