Terbium REE Collection rare earth metals elements

Terbium

Terbium is the first member of the heavy-group rare-earth elements (HREE). The naming of this element was like an elaborate “con” game. Two new elements were discovered in the same experiment, named, and switched as if the "great rare-earth sting" were planned by Redford and Newman. Were the elements labeled wrong when sent to colleagues for confirmation or was something lost in translation between the discoverer and the person registering the new elements? The terbium-erbium name switch could be labeled the first "ion exchange.”

Applications

  • Terbium in Terfenol-D expands and contracts in a magnetic field to precisely aim lasers.
  • Terbium phosphors are used in flat panel displays, trichromatic fluorescent bulbs and tubes (yellow-green), and X-ray intensifying screens (yellow-green, violet, and blue).
  • A terbium-iron-cobalt coating is used on CDs and DVDs for data storage.
  • Terbium doped silica glass (Tb:SiO2) and yttrium aluminum garnet crystals (Tb:YAG) are used in fiber-optic temperature sensors.
  • Terbium is an additive in neodymium-iron-boron (NdFeB) magnets in hybrid and electric vehicle motors allowing them to operate at high temperatures.

Interesting Facts

  • The Carl Gustav m48 is a Swedish recoilless rifle named after the discoverer of terbium—Swedish chemist, Carl Gustav Mosander.
  • The original names Mosander gave to terbia and erbia became confused and ended up being switched.
  • Terbium gallium garnets (Tb3Ga3O12) used in Faraday rotators and optical isolators rotate the plane of polarization of a light beam.

Discovery

In 1843, Swedish chemist and pharmacist Carl Gustav Mosander separated from an impure yttria the known rare-earth elements ceria, lanthana, and didymia, and was left with three oxides, one white, one yellow, and one rose pink (Mosander, 1843). The white oxide was the previously discovered element yttria, however, the yellow and pink oxides were two new rare earths, which he named, and sent forth to the foremost analytical chemists of the time for confirmation. For the new elements, Mosander named the yellow earth erbia and the rose pink element terbia. By the time they all came back, the names of the elements were somehow interchanged from their original descriptions and terbium, the name of the rose colored oxide, became the yellow oxide (Weeks and Leicester, 1968, p. 677). Terbium is named for the small village and mine location in Sweden where the yttrium-bearing mineral was discovered, Ytterby.

Definition

Terbium m is a silvery-grey metal that is relatively stable in air. The metal is malleable, ductile, and able to be cut with a knife. It has a body-centered cubic structure, a density of 8.27 gm/cm3, a melting point of 1356 °C, and a boiling point of 2800 °C. Above 1310 °C terbium becomes a hexagonal close-packed structure. Terbium oxide, or terbia, occurs as a sesquioxide with the formula Tb2O3. The oxide is a dark brown powder with a specific gravity of 7.7 gm/cm3 and a formula weight of 225.81. Terbium has one stable isotope and 36 radioactive isotopes.

Preparation of Metal

Terbium metal is typically prepared by calciothermic reduction of the trihalide, typically TbF3, in a tantalum crucible. A tungsten crucible can be used if an impurity level of 0.07 atomic weight percent tungsten could be tolerated. Terbium metal has a high melting point with a vacuum melting temperature of 1750 °C, similar to Y, Gd, and Lu. The high vacuum melting temperature necessitates a distillation step to remove tantalum impurities introduced during the reduction and vacuum melting steps. The distillation process is done in a tungsten crucible and occurs at a slow rate to keep impurities at a low level. A vacuum of better than 1.3 x 10-6 Pa is needed (Beaudry and Gschneidner, Jr., 1978). Terbium metal is formed when the fluoride preferentially separates from terbium fluoride at high temperature and combines with calcium metal forming calcium fluoride and a high-purity terbium metal.

Source

Large resources of terbium are contained in HREE-enriched minerals. Terbium occurs in the Earth’s crust at an average concentration of 0.9 parts per million. Large resources of terbium in monazite and xenotime are available worldwide in ancient and recent placer deposits, carbonatites, uranium ores, and weathered clay deposits (ion-adsorption ore). Additional large subeconomic resources of terbium occur associated in yttrium-bearing minerals in apatite-magnetite-bearing rocks, deposits of niobium-tantalum minerals, non-placer monazite-bearing deposits, sedimentary phosphate deposits, and uranium ores, especially those of the Blind River District near Elliot Lake, Ontario, Canada, which contain terbium in brannerite, monazite, and uraninite. Additional resources in Canada are contained in allanite, apatite, and britholite at Eden Lake, Manitoba; allanite and apatite at Hoidas Lake, Saskatchewan; fergusonite and xenotime at Nechalacho (Thor Lake), Northwest Territories; and eudialyte-(Y), mosandrite, and britholite at Kipawa, Quebec. It occurs in various minerals in differing concentrations and occurs in a wide variety of geologic environments, including alkaline granites, hydrothermal deposits, laterites, placers, and vein-type deposits (Hedrick, 2010). At the Ytterby Mine in Sweden terbium is a constituent in gadolinite, the first mineral in which a rare-earth element was found.

Mining

Terbium is mined from a variety of ore minerals and deposits using various methods. Monazite and xenotime are recovered from heavy-mineral sands (specific gravity >2.9) deposits in various parts of the world as a byproduct of mining zircon and titanium-minerals or tin minerals. Heavy mineral sands are recovered by surface placer methods from unconsolidated sands. Many of these deposits are mined using floating dredges which separate the heavy-mineral sands from the lighter weight fraction with an on-board wet mill through a series of wet-gravity equipment that includes screens, hydrocyclones, spirals, and cone concentrators. Consolidated or partially consolidated sand deposits that are too difficult to mine by dredging are mined by dry methods. Ore is stripped by typical earth-moving equipment with bulldozers, scrapers, and loaders or by water jet methods. Ore recovered by these methods is crushed and screened and then processed by the wet mill described above. Wet mill heavy-mineral concentrate is sent to a dry mill for processing to separate the individual heavy-minerals using a combination of scrubbing, drying, screening, electrostatic, electromagnetic, magnetic, and gravity processes (Hedrick, 1991). Vein monazite has been mined by hard-rock methods in South Africa and the United States, and as a byproduct of tungsten mining in China (Hedrick, 2010).

Terbium has also been recovered from uranium raffinates from the Elliot Lake region of Canada. In Kyrgyzstan, terbium was recovered using hard-rock methods from synchysite-(Y) from the open-pit Kutessai-II deposit near Aktyuz. Argillaceous marine sediments enriched in fossil fish remains at the Melovie deposit in Kazakhstan were previously recovered for their uranium and rare-earth content, including terbium. The main source of the world’s terbium is the ion-adsorption lateritic clays in the southern provinces of China, primarily Fujian, Guangdong, and Jiangxi, with a lesser number of deposits in Guangxi and Hunan. These deposits are mined by leaching methods (Hedrick, 2010)

Selected terbium-bearing minerals

Gadolinite-(Y) Y2Fe2+Be2(Si2O10)
Monazite (Ce,La,Nd,Th)(PO4)
Xenotime Y(PO4)
Synchysite-(Y) Ca(Y,Ce)(CO3)2F
Euxenite-(Y) (Y,Ca,Ce,U,Th)(Nb,Ti,Ta)2O6
Eudialyte-(Y) Na4(Ca,Ce)2(Fe2+,Mn,Y)ZrSi8O22(OH,Cl)2
Cerite-(Ce) (Ca,Ce)9(Fe,Mg)(SiO4)3(HSiO4)(OH)3
Mosandrite Na2Ca4(REE)(Si2O7)2OF3
Britholite-(Y) Ca2(Y,Ca)3(SiO4,PO4)3(OH,F)
Iimoriite-(Y) Y2(SiO4)(CO3)
Allanite-(Y) (Ca,Ce)(Al2,Fe+2)(Si2O7)(SiO4)O(OH) Ion adsorption lateritic clays Y-enriched lateritic clays
Brannerite (U4+,REE,Th,Ca)(Ti,Fe3+,Nb)2(O,OH)6

References

Beaudry and Bernard J. and Karl A. Gschneidner, Jr., 1978, Preparation and Basic Properties of the Rare Earth Metals: chapter 2 in Handbook of the Physics and Chemistry of Rare Earths-Volume 1:Metals, (Gschneidner, Jr. and Eyring, editors), North-Holland, New York, p. 173-232.

Gschneidner, Karl A. Jr., 2011, The Rare Earth Crisis—The Supply/Demand Situation for 2010-2015: article in Material Matters, Aldrich Chemical Co., Milwaukee, Wisconsin, v. 6, no. 2, p. 34-35.

Hedrick, James B., 2010, Rare earths: chapter in Mineral commodity summaries 2010, U.S. Geological Survey, p. 128-129.

Hedrick, James B., 1990, Rare earths—The lanthanides, yttrium, and scandium: chapter in Minerals Yearbook 1990, U.S. Geological Survey, v. 1, p. 903-922.

Hedrick, James B., 1991, Rare earths—The lanthanides, yttrium, and scandium: chapter in Minerals Yearbook 1991, U.S. Geological Survey, v. 1, p. 1211-1237.

Hedrick, James B., 2010, Yttrium: chapter in Mineral commodity summaries 2010, U.S. Geological Survey, p. 182-183.

Mosander, C. G., 1843, On the new metals, Lanthanium and didymium, which are associated with cerium; and on erbium and terbium, new metals associated with yttria: Philosophical Magazine, series 3, v. 23, no. 152, p. 241-254.

Weeks, Mary E., and Henry M. Leicester, 1968, Discovery of the Elements (7th ed.): Easton, Pennsylvania, Journal of Chemical Education, 896 p.

Electrons per shell:
2, 8, 18, 27, 8, 2
Atomic number,
Protons, Electrons:
65
Number of Neutrons:
94
Atomic Mass:
158.92534 amu
Melting Point:
1360.0 °C
Boiling Point:
3041.0 °C
Density @ 293 K:
8.27 g/cm3
Crystal structure:
hexagonal
Color:
silverish