Direct Measurement of the Magnetocaloric Effect in Gd5Si2Ge1.9Ga0.1.

Direct Measurement of the Magnetocaloric Effect in Gd5Si2Ge1.9Ga0.1.

Doping with some metals (Fe, Cu, Ga, Mn, Al) reduces or removes the strong thermal hysteresis in the giant magnetocaloric alloys Gd-5(SixGe1-x)(4). We present heat capacity and direct measurements of the isothermal entropy change, Delta S-T, and adiabatic temperature increment, Delta T-S, of Gd5Si2Ge1.9Ga0.1. T-C = 293.6 +/- 0.2 K is quite higher than in the non-substituted alloys and similar to the values in the Si rich compounds (i.e. x > 0.5). The results indicate that even this small addition of Ga makes the transition of second-order type, as a usual magnetic transition in the orthorhombic phase. The magnetocaloric parameters are lower than in the non-substituted compound and comparable to those for pure Gd.