Neodymium magnets. Introduced in 1983, Neodymium Iron Boron, is now the most common and cheapest of these particularly high-energy materials. They are produced by pressing powder in a very high magnetic field and sintering. Due to the nature of the material it is necessary, except in special circumstances, for the magnet to be supplied with a coating that prevents corrosion. Whilst they do appear expensive, their ability to allow miniaturisation of the user product means that in terms of energy for unit volume the materials are quite cheap
Typical Bhmax range 207 to 326 kJ/m³ (26 to 41 MGOe)