See-through magnets hang tough

Researchers from the Independent University of Barcelona (UAB) and the University of Zaragoza in Spain have found a way to form transparent, durable, lightweight magnets that maintain their magnetism in magnetic fields and high temperatures.

The combination of magnetism and transparency makes it possible to use the material to control light, making it potentially useful for modulating lasers and controlling holograms. The material is also an electrical insulator and could eventually be used in sensors, actuators and for recording, according to the researchers.

To produce the material, the researchers dispersed magnetic neodymium-iron-boron particles in silica aerogel, aligned the particles using a magnetic field, then dried the gel. Aerogels are highly porous, which makes them lightweight. The magnetic particles were less than five microns in diameter -- or about the size of red blood cells.

The researchers material differs from existing magnetic aerogels because it is magnetically hard, meaning it does not lose its magnetic orientation in the presence of a magnetic field, according to the researchers.

The material will be ready for use in commercial products in five to ten years, according to the researchers. The work appeared in the June 16, 2003 issue of Applied Physics Letters.