Where are the rare earth elements in electronics?
The &quot;rare earth elements&quot; are in several places in common electronics.
Strong magnets commonly use rare earth elements.
Ceramic capacitors also use rare earth elements.  Pretty much any piece of modern electronic equipment will contain ceramic capacitors.
Semiconductors (transistors, diodes, and the integrated circuits built from them) all use various amounts of rare earth elements.  Pure silicon is a semiconductor by itself, but it doesn't do much of interest.  It has to have specific amounts of &quot;impurities&quot; (properly called dopants) to get it to do the cool things it does.  Those dopants are purposefully (and carefully) introduced in specific amounts in specific places to make silicon semiconductor devices work.
You'll rarely (if at all) see the rare earth elements listed in a datasheet.  The datasheets tell you how a part works and how to use it, not what it is made of.