Effects of the Substitution of 20% Nd for La or Doping with 20% C on the Magnetic Properties and Magnetocaloric Effect in LaFe11.5Si1.5 Compound

Abstract

The effects of element substitution and element doping on the magnetic properties and magnetocaloric effect of the LaFe11.5Si1.5 compound were investigated. The crystals of the LaFe11.5Si1.5, La0.8Nd0.2Fe11.5Si1.5, and LaFe11.5Si1.5C0.2 compounds all showed cubic NaZn13-type structures, but the lattice of the La0.8Nd0.2Fe11.5Si1.5 shrank and the lattice of the LaFe11.5Si1.5C0.2 expanded. All three compounds had the characteristic of first-order magnetic transition due to the obvious itinerant-electron metamagnetic (IEM) transition occurring above Curie temperature (TC). For the LaFe11.5Si1.5, La0.8Nd0.2Fe11.5Si1.5, and LaFe11.5Si1.5C0.2 compounds, the TC were approximately 194 K, 188 K, and 232 K, respectively. Meanwhile, the maximum magnetic entropy changes (−ΔSM) under a magnetic field change of 0–3 T were approximately 18.7 J/kg·K, 22.8 J/kg·K, and 16.4 J/kg·K, respectively. The TC was mainly affected by the lattice constant. Furthermore, the −ΔSM was mainly affected by the latent heat of the first-order magnetic transition.