Rare earth element-Basic rare earth knowledge for training class (1)

 From Wikipedia



rare earth element (REE) or rare earth metal (REM), as defined byIUPAC, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides,as well as scandium and yttrium.Scandium and yttrium are considered rare earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.

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

 Despite their name, rare earth elements are – with the exception of the radioactive promethium – relatively plentiful in Earth`s crust, with cerium being the 25th most abundant elment  at 68 parts per million, or as abundant as copper. They are not especially rare, but they tend to occur together in nature and are difficult to separate from one another. However, because of their geochemical properties, rare earth elements are typically dispersed and not often found concentrated as rare earth minerals in economically exploitable ore deposits.The first such mineral discovered was gadolinite, a mineral composed of cerium, yttrium, iron, silicon and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden; four of the rare earth elements bear names derived from this single location.


A table listing the seventeen rare earth elements, their atomic number and symbol, the etymology of their names, and their main usages (see also Applications of lanthanides) is provided here. Some of the rare earth elements are named after the scientists who discovered or elucidated their elemental properties, and some after their geographical discovery.


Z Symbol Name Etymology Selected applications
39 Y Yttrium after the village of Ytterby, Sweden, where the first rare earth ore was discovered. Yttrium aluminium garnet (YAG) laser, yttrium vanadate (YVO4) as host for europium in television red phosphor, YBCO high-temperature superconductorsyttria-stabilized zirconia(YSZ), yttrium iron garnet (YIG) microwave filters,energy-efficient light bulbs,spark plugs, gas mantles, additive to steel
70 Yb Ytterbium after the village of Ytterby, Sweden. Infrared lasers, chemical reducing agentdecoy flaresstainless steelstress gaugesnuclear medicine
69 Tm Thulium after the mythological northern land of Thule. Portable X-ray machinesmetal-halide lampslasers
65 Tb Terbium after the village of Ytterby, Sweden. Additive in Neodymium based magnets, Green phosphorslasersfluorescent lampsmagnetostrictive alloys such as Terfenol-D
21 Sc Scandium from Latin Scandia(Scandinavia). Light aluminium-scandium alloys for aerospace components, additive in metal-halide lampsand mercury-vapor lamps,radioactive tracing agent in oil refineries
62 Sm Samarium after mine official, Vasili Samarsky-Bykhovets. Rare-earth magnetslasersneutron capturemasers
61 Pm Promethium after the TitanPrometheus, who brought fire to mortals. Nuclear batteriesluminous paint
59 Pr Praseodymium from the Greek "prasios", meaning leek-green, and "didymos", meaning twin. Rare-earth magnetslasers, core material for carbon arc lighting, colorant in glasses and enamels, additive in didymium glass used in welding goggles,ferrocerium firesteel(flint) products.
60 Nd Neodymium from the Greek "neos", meaning new, and "didymos", meaning twin. Rare-earth magnetslasers, violet colors in glass and ceramics, didymium glass, ceramic capacitors
71 Lu Lutetium after Lutetia, the city that later became Paris. Positron emission tomography – PET scan detectors, high-refractive-index glass, lutetium tantalate hosts for phosphors
57 La Lanthanum from the Greek "lanthanein", meaning to be hidden. High refractive index and alkali-resistant glass, flint, hydrogen storage, battery-electrodes, camera lenses, fluid catalytic cracking catalyst for oil refineries
67 Ho Holmium after Stockholm (in Latin, "Holmia"), native city of one of its discoverers. Lasers, wavelength calibration standards for optical spectrophotometersmagnets
64 Gd Gadolinium after Johan Gadolin(1760–1852), to honor his investigation of rare earths. High refractive index glass or garnetslasersX-ray tubescomputer memoriesneutron captureMRI contrast agentNMR relaxation agent, magnetostrictive alloys such as Galfenol, steel additive
63 Eu Europium after the continent of Europe. Red and blue phosphorslasersmercury-vapor lampsfluorescent lampsNMR relaxation agent
68 Er Erbium after the village of Ytterby, Sweden. Infrared lasersvanadium steelfiber-optic technology
66 Dy Dysprosium from the Greek "dysprositos", meaning hard to get. Additive in Neodymium based magnetslasersmagnetostrictive alloys such as Terfenol-D
58 Ce Cerium after the dwarf planet Ceres, named after the Roman goddess of agriculture. Chemical oxidizing agent, polishing powder, yellow colors in glass and ceramics, catalyst for self-cleaning ovensfluid catalytic cracking catalyst for oil refineries, ferroceriumflints for lighters


 The following abbreviations are often used:

· RE = rare earth

· REM = rare-earth metals

· REE = rare-earth elements

· REO = rare-earth oxides

· REY = rare-earth elements and yttrium

· LREE = light rare earth elements (Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, and Gd; also known as the cerium group)

· HREE = heavy rare earth elements (Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu; also known as the yttrium group)

The densities of the LREEs (as pure elements) range from 2.989 (scandium) to 7.9 g/cc (gadolinium), whereas those of the HREEs are from 8.2 to 9.8, except for yttrium (4.47) and ytterbium (between 6.9 and 7). The distinction between the groups is more to do with atomic volume and geological behavior (see lower down).