New magnets with 99% air content

Researchers from the Physics Department at the Universitat Autònoma de Barcelona (UAB), the Institut de Ciènca de Materials de Barcelona (ICMAB-CSIC), and the Universidad de Zaragoza have created a new ultra-light transparent magnetic material. Thanks to its properties, the new material could have interesting technological applications, such as creating new types of flat screens and magneto-optical memory devices for computers.

The researchers have obtained the new ultra-light magnets by combining silica aerogel (aerogels are extremely light solid materials, and are so porous that they’re made up of 99% air) with extremely fine magnetic particles composed of neodymium, iron and boron (Nd2Fe14B). These were orientated through a magnetic field during the synthesis. The new material retains the transparent and light properties of the aerogel, as well as the magnetic properties of the chemical composition. The magnets obtained by the researchers in the laboratory have a cylindrical shape about 1cm in diameter and several centimetres in length.

Until now, all aerogels with magnetic properties created in other laboratories were too “soft”, from a magnetic point of view, for storing information, and this closed all windows of opportunity on many technological applications. A weak external magnetic field could easily erase any information stored.

The new material created by UAB researchers firmly retains the orientation of its magnetic field, just like with a traditional magnet, making it very attractive for using in permanent magnetic memories. Because this new material allows light to travel through, its properties could simplify the design of magneto-optical memory devices, which would eventually be read by a laser beam. Furthermore, the material can be transparent or opaque according to the direction in which it is observed, making it potentially useful for creating flat screens similar to LCDs. With 99% air content, aerogel is the lightest material made to date. It is so light that some have called it “frozen fog”. Due to its extremely porous composition, it has the lowest levels of thermal, electrical and sound conductivity, making it the material with the best isolation properties.

Aerogels are produced via an extremely complex process. Firstly, a chemical solution containing water – the “gel” – is dried in special conditions in order to eliminate the water molecules and substitute them for air, so that a hugely porous solid material is obtained.