Neodymium – Super Strength Magnets

The Rare Earth Metal Used in Electric Cars and Wind Turbines

An overview of the chemistry and applications of the lanthanide rare earth element neodymium, a constituent of super-strength magnets used to minaturise electric motors.

One of the most widely used of the group of elements known as lanthanides or rare earth elements, is neodymium. It is the largest constituent of a new type of high-strength magnets that are used to increase the power and reduce the size and weight of electric motors. This makes them indispensible for the new generation of hybrid and electric cars, the miniaturisation of hard disk drives, and also the construction of wind turbines, which also depend on strong magnetic fields to generate electricity.

Chemistry of Neodymium

Neodymium (chemical symbol Nd) is an element with the atomic number of 60, meaning that the nucleus of each atom has 60 protons. As a pure substance it has a silvery-grey colour, but it is one of the most reactive lanthanides, so it quickly tarnishes in the presence of air. It is found in nature as an ore in minerals such as monazite and bastnasite (Source: Corrosion Source Handbook).

Discovered by Mosander and Von Welsbach

The famous Swedish chemist, Carl Gustaf Mosander, was the discoverer of many of the rare earth elements, but one oxide he separated, whose element he named didymium, was in fact a mixture of two elements. This was shown by an Austrian chemist, Baron Carl Auer von Welsbach, in 1885, when he separated neodymium from praseodymium, another lanthanide. By the 1950s, neodymium was being commercially produced from monazite through an ion exchange process.

Colour-changing Glass

The first commercial use of neodymium was in the pigmentation of glass. This glass, produced by the inclusion of neodymium oxide, appears lavender in colour in daylight or incandescent light, but pale blue under fluorescent light. If gold or selenium is also added to the glass, red colours result. Neodymium is also an important constituent of the alloy of rare earth metals known as “mischmetal” which is used in the flint mechanism of many cigarette lighters.

Super Magnets

The commercial demand for neodymium, however, has dramatically increased in recent years due to the discovery of super-strength magnets made from an alloy of neodymium with iron and boron (Nd2Fe14B). The alloy was discovered in 1982, by General Motors, Sumitomo Special Metals and the China Academy of Science, in response to the high price of samarium-cobalt magnets which were the first type of rare earth magnets to be commercialised.

Neodymium magnets have a much higher magnetic strength than other permanent magnets and so are used in a wide range of modern technological applications which require permanent magnets: their greater strength allows the use of smaller, lighter magnets. This range of uses includes magnetic resonance imaging (MRI), magnetic guitar pickups, loudspeakers and headphones, and motors in cordless tools, power steering and hybrid and electric vehicles. Each Toyota Prius car requires one kilogram of neodymium. (As Hybrid Cars Gobble Rare Metals, Shortage Looms, Steve Gorman, 2009, Reuters)

China’s Rare Earth Monopoly

The growing dependence of new environmentally friendly technology on the rare earth metals has raised concern over the continuing availability of these materials. For many years, China has produced and supplied them to the rest of the world, but recent developments in which export quotas have been reduced and export taxes increased has changed the landscape. The technology industry has had to either relocate production facilities to China, or look elsewhere for rare earth deposits.