The rare earths are a group of
17 elements comprising the 15 lanthanide* elements (atomic
numbers 57 through 71) plus scandium (Sc, 21) and yttrium
(Y, 39). They are all chemically similar and always found
together in mixed mineral ores. The name “rare” comes from
the fact that these elements were discovered in a rare ore
in Sweden in 1794, and “earth” refers to the fact that these
elements occur as metal oxides with high melting points and
are not easily reducible. In fact, we now know that yttrium,
neodymium and some other rare earths occur in greater abundance
than tin or cobalt. But because of the chemical similarity
of the rare earths, sophisticated technologies are required
for separation and refinement. Using proprietary technologies,
Shin-Etsu has been producing high-purity rare earths from
raw ore and supplying them to customers as oxides, metals
and in other forms since 1967.
* Lanthanides: lanthanum (La), cerium (Ce), praseodymium (Pr),
neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),
gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho),
erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu),
although promethium does not occur naturally on earth.
Characteristics & Applications
Yttrium and europium are used for red phosphors; terbium,
lanthanum and cerium for green; and europium for blue.
These phosphors are used to tri-color fluorescent lamp.They are also used in the backlights of LCD
TVs, and in plasma and CRT TVs.
- Hydrogen storage
Compared to other alloys, rare earth alloys have a
faster hydrogen absorption and release rate, and reach
equilibrium at lower pressure, making it possible
to store hydrogen at room temperature.
- Magnetic materials
Neodymium, samarium and cerium have outstanding properties
as magnetic materials, enabling production of smaller,
more powerful magnets.
- The high-tech sector
Rare earths are also being used in a growing number
of high-tech applications including cell phone components,
fine ceramics, superconductors, and mini-discs (MD).