Neodymium iron boron magnet

Neodymium iron boron magnets, commonly referred to as neodymium magnets or NdFeB, NIB or Neo magnet, are magnets made from a sintered alloy of neodymium, iron, and boron. They produce the highest commercially available magnetic fields (approximately 1 tesla) and make paramagnetism and diamagnetism in materials far more visible than most other magnets. They are also a common source of neodymium because they are relatively easy to obtain from different everyday objects. Due to their high field strengths large neodymium magnets may cause damage to objects if they are allowed near ferromagnetic materials, and can break bones easily.

Chemical

The alloy inside the magnets is primarily composed of macroscopic Nd₂Fe₁₄B grains, surrounded by a Nd-rich matrix layer (~90% Nd). For amateur chemist purposes, they can be assumed to be composed entirely of Nd₂Fe₁₄B alloy.

Neodymium magnets are plated in a oxidation-resistant layer of copper, nickel, and/or gold, with possible tin and mercury additives. When this layer is broken, they will react vigorously with acids to produce corresponding neodymium and iron salts, as well as boron or boric acid depending on the acid chosen.

2 Nd₂Fe₁₄B + 35 H₂SO₄ -> 4 Nd₂(SO₄)₃ + 28 FeSO₄ + 2 H₃BO₃ + 3 SO₂ + 35 H₂

Physical

Neodymium magnets are a dark gray, grainy sintered alloy coated with a mechanically polished, electroplated layer of protective metals such as nickel, copper, tin, and/or gold.

Availability

Almost all rare-earth permanent magnets are made of this material.

Projects

Extracting neodymium from magnets

Is difficult for the home chemist. Witness the epic that is The trouble with Neodymium thread. Also, *Isolation of neodymium from magnets is another good thread of information.

Handling

Storage

In closed containers, away from moisture and acidic vapors.

Disposal

Best to recycle it.