Bulk and high-energy ball-milled Gd5Si2Ge2: Comparative study of magnetic and magnetocaloric properties

High-energy ball milling was employed to produce small particles of Gd5Si2Ge2. Magnetic and magnetocaloric properties of the ball-milled and bulk Gd5Si2Ge2 samples were investigated through the magnetization measurements. When compared to the bulk material, a significant decrease in saturation magnetization and magnetocaloric effect (- ΔSmax = 4 vs. 20 J/kgK for ΔH = 0–5 T) is observed even after the relatively short ball milling time of 4 h which produced particles with an average size of ca. 0.5 μm. The ball-milled samples appear to loose a first-order structural transition, present in bulk Gd5Si2Ge2, and display a superparamagnetic behaviour below the corresponding Curie temperatures.