Rare earth element

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As defined by IUPAC, rare earth elements or rare earth metals are a collection of seventeen chemical elements in the periodic table, namely scandium, yttrium, and the fifteen lanthanides.[1] Scandium and yttrium are considered rare earth elements since they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.

Despite their name, rare earth elements (with the exception of the highly unstable promethium) are relatively plentiful in the Earth's crust, with cerium being the 25th most abundant element at 68 parts per million (similar to copper). However, because of their geochemical properties rare earth elements are typically dispersed and not often found in concentrated and economically exploitable forms known as rare earth minerals.[2] It was the very scarcity of these minerals (previously called "earths") that led to the term "rare earth". The first such mineral discovered was gadolinite, a compound of cerium, yttrium, iron, silicon and other elements. This mineral was extracted from a mine in the village of Ytterby, Sweden; many of the rare earth elements bear names derived from this location.

Contents

List

A table listing the seventeen rare earth elements, their atomic number and symbol, the etymology of their names, and their main usages is provided here. Some of the rare earths are named for the scientists who discovered or elucidated their elemental properties, and for their geographical discovery.

Abbreviations

The following abbreviations are often used:

  • RE = rare earth
  • REM = rare earth metals
  • REE = rare earth elements
  • REO = rare earth oxides
  • LREE = light rare earth elements (La-Sm)
  • HREE = heavy rare earth elements (Eu-Lu)

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