Lawrence Livermore National Laboratory researchers have developed a new, more efficient permanent magnet that removes the deficiencies of conventional samarium and neodymium magnets.

The proposed magnet stems from the well-known samarium and cobalt (SmCo₅, CaCu₅-type structure) magnet, but goes a step further and substitutes most of the cobalt with iron and nickel.

More modern neodymium magnets have an advantage over SmCo₅ because of their greater maximum energy. But the new magnet removes most of the disadvantages of SmCo₅ while preserving its superior high-temperature efficiency over the neodymium magnets.

Unfortunately, substituting all cobalt atoms for iron, — which has a larger magnetic moment that helps increase the maximum energy product — makes the ordinary hexagonal phase thermodynamically unstable. This phase, however, is critical for the materials properties and it must be retained for a practical magnet. The Lab researchers were able to circumvent this problem and stabilize the hexagonal phase by adding a small amount of nickel.

Using first-principles electronic-structure calculations, Lawrence Livermore scientists Per Soderlind, Alexander Landa, Daniel Aberg, Marcus Dane and Patrice Turchi found that their new magnet (SmCoNiFe₃) has very promising magnetic properties and could replace SmCo₅ or neodymium magnets in various applications.

The new efficient permanent magnet substitutes most of the cobalt in SmCo₅ with iron and dopes it with a small amount of nickel. “This is a very timely discovery because the cobalt prices are up and have nearly doubled this year because of the anticipated demand for lithium-ion-cobalt batteries,” Soderlind said. “Iron, on the other hand, is abundant and very inexpensive.”

The researchers also have filed a provisional patent based on this research.