Making Rare-Earth Magnets Without Rare-Earth Elements

Lithium-Iron Nitrogen Magnet
A crystal of lithium-iron-nitride. Credit: Ames Laboratory/Department of Energy

Rare-earth magnets are a type of permanent magnet with high magnetic strength. A magnet’s strength is due to two factors: field strength and anisotropy. Field strength is the magnitude and direction of the magnet’s magnetic field. Anisotropy is the ability of the magnet to maintain its direction of the magnetic field. Rare-earth magnets have the distinction of having both high field strength and high anisotropy. This is why they are found in computer hard drives, magnetic levitation trains, and electric motors. The main problem with rare-earth magnets is they contain rare-earth metals. Rare-earths are elements that make up the lanthanide elements (elements 57-81), scandium and yttrium. They were originally called rare-earths because they are relatively rare elements in nature. Materials using these elements tend to be expensive and rely on few suppliers. Scientists at Ames Laboratory have discovered a way to make magnets with rare-earth properties using ordinary, inexpensive iron. They discovered iron will dissolve when introduced into a solution of lithium and nitrogen. Crystals grown from the new solution had magnetic anisotropy an order magnitude stronger than commercially available permanent magnets. This discovery could lead to new magnets that do not rely on expensive materials. Manufacturing and magnetic property details appeared in Nature Communications.