Giant magnetocaloric effect in Gd5(Si2Ge2) alloy with low purity Gd

Abstract

Gd 5 (Ge 1-x Si x), x ≤ 4 based alloys are potential candidates for magnetic refrigeration in the range ~20-~290 K. However, one of the greatest obstacles for the use of that technology in large scale is the utilization of high pure Gd metal (99.99 wt. (%)) to produce the GdGeSi alloys, since the impurity elements decrease the intensity of the magnetocaloric effect (EMC) 1. In this work, we prove that annealing of the Gd 5 Ge 2 Si 2 can promote remarkable values for the EMC in comparison to those obtained for the alloy with high pure Gd. Also, the as cast alloy and the annealed alloy are not monophasic, but have at least two crystalline phases in their microstructure. Results for X-ray analysis, optical and electronic microscopy and magnetization measurements are reported.