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What Are Neodymium Magnets?

What Are Neodymium Magnets?

Posted by Applied Magnets on 2nd Jun 2022

A neodymium magnet (also known as NdFeB, NIB or Neo magnet) is the most popular and strongest rare-earth magnet available, and it is used all around the world. It consists of  a combination of neodymium, boron, and iron which bonds and creates the structure known as Nd2Fe14B tetragonal crystalline.

NdFeB magnets can be labeled as a solid that has strong binding qualities, or a mass that heats very well and can be smelted.  This really depends on the type of manufacturing procedure that is being enforced. There are many uses for these magnets which range from electrical equipment, tools, cars, fasteners, computers, and alike. 

History

General Motors and Sumitomo Special Metals separately own the title of evolving this magnet in 1984.  One of the developers (Sumitomo) created a full density model Nd2Fe14B magnet that is smelted, while the other developer (GM) concentrated more on a Nd2Fe14B magnet that centered on being spun and melted known more commonly as a nanocrystalline.  Both of these creators focused on basing their developments on finding a lower cost for materials to be used, and steering further away from the expensive prices of Samarium Cobalt (SmCo) magnets.

Sumitomo grew to become Hitachi Corporation, who focused primarily on the business development of sintered (or smelted) neodymium magnets.  Because of the highly desired need for these magnets, Hitachi has protected at least 600 patents pertaining to neodymium.  GM decided to industrialize several other different types of neodymium products into what became a distribution company called Magnequench in 1986.  They primarily focused on distributing melt-spun Nd2Fe14B magnets to manufacturers who were seeking the powder form.

The production and manufacturing of neodymium has predominately been through China.  They control about 65% of mining and 90% of manufacturing of the entire world's production of these rare-earth magnets. Alternatives have been attempted and sprung up sporadically throughout the Western cities and countries, but because of the limitations brought by laws concerning the environment, countries such as the United States of America are highly restricted from having a close competition to China.

Why Are Neodymium Magnets So Strong?

Neodymium is a magnetic metal that is able to be antiferromagnetic, or in other words, has an antiparallel alignment of adjacent electron spins in a crystal lattice.  When this metal is found in pure form, the magnetism it holds only appears at low temperatures, usually below -425.5 F.  When this metal comes in contact with iron, however, it opposes and becomes ferromagnetic, and the metal's magnetic strength can endure as high as room temperatures. 

There are several reasons why the neodymium magnet has such a strong power.  The main reason the whole structure is strong is simply because it's tetragonal crystals of this particular material prefer to magnetize along a specific crystal axis, and not magnetize in different directions.  This is called uniaxial magnetocrystalline anisotropy.

During the manufacturing process, the neodymium compound of microcrystalline grains fall under a very strong magnetic field, which causes them to face the same direction.  The strong opposing magnetization of the crystal lattice and the attempt to force it to turn directions is why this structure has a powerful reluctance to become demagnetized.

The iron atom is composed of only 3 unpaired electrons (on avg) in it's whole makeup, and the neodymium structure has 4.  Because neodymium has 4, it is able to have an equally distanced set of unpaired electrons that spin in the same direction and are aligned, thus creating a large dipolar magnetic field.