Rare Earth Magnets
Name: Bobby O.
What exactly are rare-earth magnets and how are they formed?
Rare earths are the 14 elements in the periodic table that start with the
element Lanthanum and end with the element Luthecium.
The rare earth elements are magnetic because their 4f shells are not full.
The elements as one moves to the right in the periodic table fill one
electron at a time. The 4f shells each can have two spin states, up or down.
Because it is more energetically favorable, Hunds Rule, the 1st 7 electrons
fill with their spins all up. Spin state for Eu is around 7 times 1/2 (from
Rare earth magnets are made from rare-earth elements. Typically these are
compounds or composites with Fe.
Dr. Harold Myron
The rare earths, also called the "lanthanides" have unpaired electrons in
their "f" orbitals.
Various compounds of these elements are used to produce very strong magnets.
The particular compounds depends upon both chemical, engineering, and
economic considerations. Search the term: "rare earth magnets" on the
Internet and I think you will find a wealth of info -- probably more than
you want to know.
Click here to return to the Physics Archives
Update: June 2012