| Revision as of 19:00, 3 June 2005 editYekrats (talk | contribs)Extended confirmed users, Pending changes reviewers2,893 editsm +eo← Previous edit | Revision as of 21:27, 7 September 2005 edit undoMoogsi (talk | contribs)Extended confirmed users1,266 edits merged info from Rare earth, please see Talk:Rare earth elementNext edit → | ||
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| The '''rare earth''' |
The '''rare earth elements''' or '''rare earth metals''' are a relatively abundant group of 17 ]s (see ]) composed of ], ], and the ]s. The lanthanide ], which does not occur naturally on Earth, is generally not considered a rare earth element. | ||
| They were originally described as 'rare' because they were unknown in their elemental form, and difficult to extract from the rocks that contained them. Sometimes they are still loosely referred to as ']s', though strictly this is the name for their ]s. | |||
| ⚫ | The principal economic sources of rare earths are the minerals ], ], and ] and the lateritic ion-adsorption clays. The elements range in crustal abundance from ], the 25th most abundant element of the 78 common elements in the Earth's crust at 60 parts per million, to ] and ], the least abundant rare-earth elements at about 0.5 |
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| The elemental forms of rare earths are iron gray to silvery lustrous ]s that are typically soft, malleable, and ductile and usually reactive, especially at elevated temperatures or when finely divided. All rare earth elements dissolve in acid to form triply charged ions in solution, and +3 is the default oxidation state. | |||
| The rare earths' unique properties are used in a wide variety of applications. For example, their ]s are widely used as dopants in ] such as Nd<sup>3+</sup>:YAG (neodymium-doped yttrium aluminum garnet) and ]s. Half-full ] in these elements can be used to produce exceedingly strong ], with ] holding the record for highest ] and ] having the highest known ]ization of any material. | The rare earths' unique properties are used in a wide variety of applications. For example, their ]s are widely used as dopants in ] such as Nd<sup>3+</sup>:YAG (neodymium-doped yttrium aluminum garnet) and ]s. Half-full ] in these elements can be used to produce exceedingly strong ], with ] holding the record for highest ] and ] having the highest known ]ization of any material. | ||
| ⚫ | The principal economic sources of rare earths are the minerals ], ], and ] and the lateritic ion-adsorption clays. The moniker "rare earth" can be misleading – the elements range in crustal abundance from ], the 25th most abundant element of the 78 common elements in the Earth's crust at 60 parts per million (more common than lead), to ] and ], the least abundant rare-earth elements at about 0.5 parts per million. | ||
| {{chem-stub}} | {{chem-stub}} | ||
Revision as of 21:27, 7 September 2005
The rare earth elements or rare earth metals are a relatively abundant group of 17 chemical elements (see Periodic Table) composed of scandium, yttrium, and the lanthanides. The lanthanide promethium, which does not occur naturally on Earth, is generally not considered a rare earth element.
They were originally described as 'rare' because they were unknown in their elemental form, and difficult to extract from the rocks that contained them. Sometimes they are still loosely referred to as 'rare earths', though strictly this is the name for their oxides.
The elemental forms of rare earths are iron gray to silvery lustrous metals that are typically soft, malleable, and ductile and usually reactive, especially at elevated temperatures or when finely divided. All rare earth elements dissolve in acid to form triply charged ions in solution, and +3 is the default oxidation state.
The rare earths' unique properties are used in a wide variety of applications. For example, their ions are widely used as dopants in active laser media such as Nd:YAG (neodymium-doped yttrium aluminum garnet) and Erbium-doped fiber amplifiers. Half-full f shells in these elements can be used to produce exceedingly strong permanent magnets, with Samarium-Cobalt holding the record for highest Curie temperature and Neodymium-Iron-Boron having the highest known permanent magnetization of any material.
The principal economic sources of rare earths are the minerals bastnasite, monazite, and loparite and the lateritic ion-adsorption clays. The moniker "rare earth" can be misleading – the elements range in crustal abundance from cerium, the 25th most abundant element of the 78 common elements in the Earth's crust at 60 parts per million (more common than lead), to thulium and lutetium, the least abundant rare-earth elements at about 0.5 parts per million.
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