Phase, structural, and magnetocaloric properties of high temperature annealed LaFe11.6Si1.4BX

The phase relation, microstructural, hysteresis, Curie temperature, and magnetocaloric effects of LaFe11.6Si1.4Bx (x = 0.1, 0.2, 0.3, 0.4, and 0.5) prepared by arc-melting and then annealed at 1373 K (1.5 h) + 1523 K (5 h) were investigated. It was found that the main phase is NaZn13-type phase, the impurity phases include alpha-Fe, Fe2B, and small amount of La5Si3. The boron atom can dissolve into the crystal lattice of LaFe11.6Si1.4Bx to form interstitial solid solution, but the content of solid solution is not up to x = 0.5. For LaFe11.6Si1.4Bx (x = 0.1.0.3, and 0.5) compounds, the Curie temperature T-C increases from 190.6 to 198.3K with the increasing of B content from x =0.1 to 0.5. The first order magnetic transition behavior becomes weaker and magnetic entropy change Delta S-M (T, H) drops with the increasing of B content, respectively. However, Delta S-M (T, H) still remains a large value, 11.18J/kgK, when x reaches to 0.5 at 0-2T. An attractive feature is that both thermal and magnetic hysteresis can be reduced remarkably by introducing B. The maximum magnetic hysteresis loss near T-C drops from 22.52 to 4.95 J/kg when the content of B increases from x = 0.1 to 0.5. (C) 2010 Elsevier B.V. All rights reserved.