Room temperature ferromagnetic nanoparticles of Gd5Si4

Gd₅(Si_xGe_1-x)₄ compounds undergo first order phase transitions close to room temperature when x @ 0.5, which are accompanied by extreme changes of properties. We report the fabrication of nanoparticles of one of the parent compounds - Gd₅Si₄ - using high energy ball milling. Crystal structure, microstructure and magnetic properties have been investigated. Particles agglomerate at long milling times and the particles that are milled longer than 20 min lose crystallinity and no longer undergo magnetic phase transition close to 340 K, which is present in a bulk material. Samples milled for more than 20 min exhibit a slightly increased coercivity.