Sintered neodymium-iron-boron (NdFeB) magnets, also referred to as "neo" magnets, have been commercially available since November 1983. NdFeB magnets offer the highest energy product of any material today and are available in a very wide range of shapes, sizes and grades. Earliest use of NdFeB magnets was primarily for voice coil motors (VCM's) in hard disk drives and this market still accounts for about 50% of total sales dollars. Other applications include high performance motors, brushless DC motors, magnetic separation, magnetic resonance imaging, sensors and loudspeakers.

NdFeB magnets have very high magnetic properties, their (BH)Max value is about 3 to 10 times highter than sintered ferrite magnets, Hcj value is 5 to 10 times higher than sintered ferrite and 5 to 15 times higher than Alnico magnets. The potentail magnetic properties of NdFeB magnets are very high , theoretically, their (BH)Max value can be as high as 527 KJ/M^3(66MGOe), they can even attract object which weight is 640 times higher than themself.

Although the Curie temperature for NdFeB materials is 310 degrees for 0% cobalt-containing material to greater than 370 degrees for 5% cobalt-containing, some irreversible loss of output may be expected at even moderate temperatures. Neo magnets also have a moderately high Reversible Temperature Coefficient of Induction which reduces total magnetic output as temperature rises. Selection of neo magnets instead of SmCo, for example, is a function of the maximum temperature of the application, required magnetic output at typical use temperature and total cost of the system.

Neo magnets also have some limitations due to their corrosion behavior. In humid applications, a protective coating is highly recommended. Coatings which have been used successfully include, E-coat (a liquid dip epoxy coating), dry electrostatic spray epoxy, nickel plating and combinations of these coatings. Changes in composition and processing over the past several years have resulted in significant improvements in corrosion resistance and high temperature performance.