Rare-earth element

Rare-earth elements
in the periodic table

A rare-earth element (REE) or rare-earth metal (REM), as defined bi IUPAC, is ane o a set o seventeen chemical elements in the periodic cairt, specifically the fifteen lanthanides, as well as scandium an yttrium. Scandium an yttrium are considered rare-earth elements acause thay tend tae occur in the same ore deposits as the lanthanides an exhibit seemilar chemical properties. For the same set o mineralogical, chemical, physical (especially electron shell configuration), an relatit reasons, a broader definition o rare earth elements includin the actinides is encountered in some cases. Thorium is a significant component o monazite an ither important rare earth minerals, an uranium an decay products are foond in others.^[1] Baith series o elements begin on the periodic table in group 3 unner yttrium an scandium.

Rare-earth elements are cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), an yttrium (Y).

Despite thair name, rare-earth elements are – wi the exception o the radioactive promethium – relatively plentiful in Yird's crust, wi cerium bein the 25t maist abundant element at 68 pairts per million, mair abundant than copper. Thay are nae especially rare, but thay tend tae occur thegither in naitur an are difficult tae separate frae ane anither. Houiver, acause o thair geochemical properties, rare-earth elements are teepically dispersed an nae eften foond concentrated as rare-earth minerals in economically exploitable ore deposits. The first sic mineral discovered wis gadolinite, a mineral componed o cerium, yttrium, iron, silicon, an ither elements. This mineral wis extracted frae a mine in the veelage o Ytterby in Swaden; fower o the rare-earth elements bear names derived frae this single location.

List eedit

A table listing the 17 rare-earth elements, thair atomic nummer an seembol, the etymology o thair names, an thair main usages (see an aw Applications o lanthanides) is providit here. Some o the rare-earth elements are named efter the scientists who discovered or elucidated thair elemental properties, an some efter thair geographical discovery.

Z	Seembol	Name	Etymology	Selected applications	Abundance (ppm in earth's crust)
21	Sc	Scandium	frae Latin Scandia (Scandinavia).	Licht aluminium-scandium alloys for aerospace components, additive in metal-halide lamps an mercury-vapor lamps,^[2] radioactive tracing agent in ile refineries	18-25
39	Y	Yttrium	efter the veelage o Ytterby, Swaden, whaur the first rare earth ore wis discovered.	Yttrium aluminium garnet (YAG) laser, yttrium vanadate (YVO₄) as host for europium in televeesion reid phosphor, YBCO heich-temperature superconductors, yttria-stabilized zirconia (YSZ), yttrium iron garnet (YIG) microwave filters, energy-efficient licht bulbs, spark plugs, gas mantles, additive tae steel, cancer treatments	31
57	La	Lanthanum	frae the Greek "lanthanein", meanin to be hidden.	High refractive index an alkali-resistant gless, flint, hydrogen storage, battery-electrodes, camera lenses, fluid catalytic cracking catalyst for ile refineries	39
58	Ce	Cerium	efter the dwarf planet Ceres, named efter the Roman goddess o agriculture.	Chemical oxidizing agent, polishing powder, yellow colors in gless an ceramics, catalyst for self-cleaning ovens, fluid catalytic cracking catalyst for ile refineries, ferrocerium flints for lighters	66.5
59	Pr	Praseodymium	frae the Greek "prasios", meanin leek-green, an "didymos", meanin twin.	Rare-earth magnets, lasers, core material for carbon arc lichtin, colorant in glasses an enamels, additive in didymium gless uised in welding goggles, ferrocerium firesteel (flint) products.	9.1
60	Nd	Neodymium	frae the Greek "neos", meanin new, an "didymos", meanin twin.	Rare-earth magnets, lasers, violet colors in gless an ceramics, didymium gless, ceramic capacitors, electric motors o electric automobiles	41.5
61	Pm	Promethium	efter the Titan Prometheus, who brocht fire tae mortals.	Nuclear batteries, luminous paint	1.0 x 10⁻¹⁵
62	Sm	Samarium	efter mine offeecial, Vasili Samarsky-Bykhovets.	Rare-earth magnets, lasers, neutron captur, masers, control rods o nuclear reactors	8
63	Eu	Europium	efter the continent o Europe.	Red an blue phosphors, lasers, mercury-vapor lamps, fluorescent lamps, NMR relaxation agent	.05
64	Gd	Gadolinium	efter Johan Gadolin (1760–1852), tae honour his investigation o rare earths.	High refractive index gless or garnets, lasers, X-ray tubes, computer memories, neutron captur, MRI contrast agent, NMR relaxation agent, magnetostrictive alloys sic as Galfenol, steel additive	6.2
65	Tb	Terbium	efter the veelage o Ytterby, Swaden.	Additive in Neodymium based magnets, green phosphors, lasers, fluorescent lamps, magnetostrictive alloys sic as terfenol-D, naval sonar seestems, stabilizer o fuel cells	1.2
66	Dy	Dysprosium	frae the Greek "dysprositos", meanin hard to get.	Additive in Neodymium based magnets, lasers, magnetostrictive alloys sic as terfenol-D, haurd disk drives	5.2
67	Ho	Holmium	efter Stockholm (in Latin, "Holmia"), native ceety o ane o its discoverers.	Lasers, wavelength calibration standards for optical spectrophotometers, magnets	1.4
68	Er	Erbium	efter the veelage o Ytterby, Swaden.	Infrared lasers, vanadium steel, fiber-optic technology	2.8
69	Tm	Thulium	efter the mythological northren land o Thule.	Portable X-ray machines, metal-halide lamps, lasers	0.5
70	Yb	Ytterbium	efter the veelage o Ytterby, Swaden.	Infrared lasers, chemical reducing agent, decoy flares, stainless steel, stress gauges, nuclear medicine, monitoring earthquakes	3.0
71	Lu	Lutetium	efter Lutetia, the ceety that later became Paris.	Positron emission tomography – PET scan detectors, heich-refractive-index gless, lutetium tantalate hosts for phosphors, catalyst uised in refineries, LED licht bulb	0.5

Abbreviations eedit

The follaein abbreviations are eften uised:

RE = rare earth
REM = rare-earth metals
REE = rare-earth elements
REO = rare-earth oxides
REY = rare-earth elements an yttrium
LREE = licht rare-earth elements
HREE = hivy rare-earth elements

References eedit

↑ The Elements, T Gray, 2007 Black Dog & Leventhal pp 118-122 Lanthanum and Cerium
↑ C. R. Hammond, "Section 4; The Elements", in CRC Handbook of Chemistry and Physics, 89th Edition (Internet Version 2009), David R. Lide, ed., CRC Press/Taylor and Francis, Boca Raton, FL.

[1] The Elements, T Gray, 2007 Black Dog & Leventhal pp 118-122 Lanthanum and Cerium

[CRC_ed89_elements-2] C. R. Hammond, "Section 4; The Elements", in CRC Handbook of Chemistry and Physics, 89th Edition (Internet Version 2009), David R. Lide, ed., CRC Press/Taylor and Francis, Boca Raton, FL.

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[2]