Magnetocaloric effect in Gd5(Si,Ge)4 based alloys and composites

Abstract

The research on magnetocaloric materials for applications concentrates, among other, on two parameters: the ordering temperature and the value of the magnetocaloric effect (MCE). The optimization consists in tuning the former without significant drop in the latter. These studies report on the magnetic susceptibility, magnetization curves, heat capacity and magnetocaloric effect measurements for compositionally and structurally modified Gd5Si4 compound. The modifications are based on the doping of the parent compound with an excess Gd atoms and substitution of Si with B as well as on the dimensional effect studied by mechanical milling. Moreover, composite samples of the type Gd:Gd5Si2Ge2 were investigated revealing the influence of the intergranular interactions on the magnetocaloric properties. It appears that these interventions enable a controllable steering of the ordering temperature shifting it towards the room temperature with, in some cases, minor reduction of the parameters characterizing MCE.