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Iowa State University and Ames Laboratory researchers have developed a method to create gadolinium silicide nanoparticles which retain ferromagnetic properties at room temperature.

This innovative method creates Gd5Si4 nanoparticles that retain the ferromagnetic properties of the bulk material at room temperature. These nanoparticles may be useful as an 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.

• Increased magnetic properties compared to existing MRI contrast agents

MRI contrast agent; transcranial magnetic stimulation, hyperthermic cancer treatment

1. "Investigation of Room Temperature Ferromagnetic Nanoparticles of Gd5Si4”, R.L. Hadimani et al., IEEE Transactions on Magnetics, 51, 2504104, 2015.  DOI: 10.1109/TMAG.2015.2446774

2. H. A. El-Gendy, S. M. Harstad, V. Vijayaragavan, S. Gupta, V. K. Pecharsky, J. Zweit and R. L. Hadimani "Ferromagnetic Gd5Si4 Nanoparticles as T2 Contrast Agents for Magnetic Resonance Imaging" IEEE Magnetics Letters, 2017, 8, 1507504. DOI 10.1109/lmag.2017.2728503