This innovative method creates Gd5Si4 nanoparticles that retain the ferromagnetic properties of the bulk material at room temperature. These nanoparticles may be useful as a MRI contrast agent or for other applications that would benefit from materials that highly respond to a magnetic field, such as transcranial magnetic stimulation, MRI thermometry, and hyperthermic cancer treatment.
The gadolinium-based ferromagnetic particles are produced using ball milling in an inert atmosphere. The resultant particles retain an order of magnitude greater magnetization compared to conventionally prepared gadolinium particles. Ordinary preparation methods destroy the ordered structure required for ferromagnetism, resulting in materials with the much weaker paramagnetic properties - ferromagnetic materials have a high susceptibility to magnetization when subjected to a magnetic field and retain that magnetization after the field is removed; paramagnetic materials respond to a magnetic field but do not retain any magnetization when removed from the field.