Microstructure and magnetocaloric properties of non-stoichiometric La1.5Fe12.2-xCo0.8Six alloys

In this work, we have investigated the influence of annealing temperature and Si content on the microstructure and magnetocaloric properties of non-stoichiometric La1.5Fe12.2-xCo0.8Six (x = 1.0, 1.1, 1.2, 1.4) alloys. A high content of La(Fe,Co,Si)13 phase (∼80 vol.%) can be achieved after annealing at 1000 °C for 24 h. The morphology of the 1:13 phase evolves from facet to granule accompanying the aggregation of the α-Fe particles. The Curie temperature increases with increasing annealing temperature and decreases with the increase of nominal Si content. In addition, large entropy change values of 8.4 J/kg K and 8.0 J/kg K at 2 T are obtained for La1.5Fe11.1Co0.8Si1.1 and La1.5Fe11.1Co0.8Si1.2, respectively. The large entropy change, tunable transition temperature and short-time annealing make the currently studied non-stoichiometric La-Fe-Co-Si a promising magnetic cooling material.