View source for Chemistry:Terbium

{{infobox terbium}}
'''Terbium''' is a [[Chemistry:Chemical element|chemical element]]; it has [[Chemistry:Symbol|symbol]] '''Tb''' and [[Physics:Atomic number|atomic number]] 65. It is a silvery-white, rare earth [[Chemistry:Metal|metal]] that is malleable, and ductile. The ninth member of the [[Chemistry:Lanthanide|lanthanide]] series, terbium is a fairly electropositive metal that reacts with water, evolving [[Chemistry:Hydrogen|hydrogen]] gas. Terbium is never found in nature as a free element, but it is contained in many [[Earth:Mineral|mineral]]s, including [[Chemistry:Cerite|cerite]], [[Chemistry:Gadolinite|gadolinite]], [[Chemistry:Monazite|monazite]], [[Chemistry:Xenotime|xenotime]] and [[Chemistry:Euxenite|euxenite]].

Swedish chemist [[Biography:Carl Gustaf Mosander|Carl Gustaf Mosander]] discovered terbium as a chemical element in 1843. He detected it as an impurity in [[Chemistry:Yttrium(III) oxide|yttrium oxide]], {{chem2|Y2O3}}. [[Chemistry:Yttrium|Yttrium]] and terbium, as well as [[Chemistry:Erbium|erbium]] and [[Chemistry:Ytterbium|ytterbium]], are named after the village of [[Chemistry:Ytterby|Ytterby]] in Sweden. Terbium was not isolated in pure form until the advent of [[Chemistry:Ion exchange|ion exchange]] techniques.

Terbium is used to [[Chemistry:Dopant|dope]] [[Chemistry:Calcium fluoride|calcium fluoride]], calcium [[Chemistry:Tungstate|tungstate]] and [[Chemistry:Strontium|strontium]] [[Chemistry:Molybdate|molybdate]] in solid-state devices, and as a crystal stabilizer of [[Physics:Fuel cell|fuel cell]]s that operate at elevated temperatures. As a component of [[Chemistry:Terfenol-D|Terfenol-D]] (an alloy that expands and contracts when exposed to magnetic fields more than any other alloy), terbium is of use in [[Engineering:Actuator|actuator]]s, in naval sonar systems and in [[Engineering:Sensor|sensor]]s.

Most of the world's terbium supply is used in green [[Physics:Phosphor|phosphor]]s. Terbium [[Chemistry:Oxide|oxide]] is used in [[Physics:Fluorescent lamp|fluorescent lamp]]s and television and monitor [[Engineering:Cathode-ray tube|cathode-ray tube]]s (CRTs). Terbium green phosphors are combined with divalent [[Chemistry:Europium|europium]] blue phosphors and trivalent europium red phosphors to provide trichromatic lighting technology, a high-efficiency white light used for standard illumination in indoor lighting.

== Characteristics ==

=== Physical properties ===
Terbium is a silvery-white rare earth [[Chemistry:Metal|metal]] that is malleable, ductile and soft enough to be cut with a knife.<ref name="CRC" /> It is relatively stable in air compared to the earlier, more reactive lanthanides in the first half of the lanthanide series.<ref>{{cite web| url = http://www.elementsales.com/re_exp/index.htm |title = Rare-Earth Metal Long Term Air Exposure Test| access-date = 2009-05-05}}</ref> Terbium exists in two crystal [[Physics:Allotropy|allotropes]] with a transformation temperature of 1289&nbsp;°C between them.<ref name="CRC" /> The 65 electrons of a terbium atom are arranged in the [[Physics:Electron configuration|electron configuration]] [Xe]4f<sup>9</sup>6s<sup>2</sup>. The eleven 4f and 6s electrons are [[Physics:Valence electron|valence]]. Only three electrons can be removed before the nuclear charge becomes too great to allow further ionization, but in the case of terbium, the stability of the half-filled [Xe]4f<sup>7</sup> configuration allows further ionization of a fourth electron in the presence of very strong oxidizing agents such as [[Chemistry:Fluorine|fluorine]] gas.<ref name="CRC" />

The terbium(III) cation is brilliantly [[Biology:Fluorescence|fluorescent]], in a bright lemon-yellow color that is the result of a strong green emission line in combination with other lines in the orange and red. The yttrofluorite variety of the mineral [[Chemistry:Fluorite|fluorite]] owes its creamy-yellow fluorescence in part to terbium. Terbium easily oxidizes, and is therefore used in its elemental form specifically for research. Single terbium atoms have been isolated by implanting them into [[Chemistry:Fullerene|fullerene]] molecules.<ref>{{cite journal|last1=Shimada|first1=T.|last2=Ohno|first2=Y.|last3=Okazaki|first3=T.|last4=Sugai|first4=T.|last5=Suenaga|first5=K.|last6=Kishimoto|first6=S.|last7=Mizutani|first7=T.|last8=Inoue|first8=T.|last9=Taniguchi|first9=R.|last10=Fukui|display-authors=3 | first10=N.|last11=Okubo | first11=H.|last12=Shinohara | first12=H.|title=Transport properties of C<sub>78</sub>, C<sub>90</sub> and Dy@C<sub>82</sub> fullerenes – nanopeapods by field effect transistors|journal=Physica E: Low-dimensional Systems and Nanostructures|year=2004|volume=21|issue=2–4|pages=1089–1092|doi=10.1016/j.physe.2003.11.197|bibcode = 2004PhyE...21.1089S}}</ref>

Terbium has a simple [[Physics:Ferromagnetic|ferromagnetic]] ordering at temperatures below 219 K. Above 219 K, it turns into a [[Physics:Helimagnetism|helical antiferromagnetic]] state in which all of the atomic moments in a particular basal plane layer are parallel, and oriented at a fixed angle to the moments of adjacent layers. This unusual antiferromagnetism transforms into a disordered [[Physics:Paramagnetic|paramagnetic]] state at 230 K.<ref>{{cite journal| author =Jackson, M. | title =Magnetism of Rare Earth| url =http://www.irm.umn.edu/quarterly/irmq10-3.pdf | journal = The IRM Quarterly | volume =10| issue = 3| page = 1| date = 2000}}</ref>

=== Chemical properties ===
Terbium metal is an electropositive element and oxidizes in the presence of most acids (such as sulfuric acid), all of the halogens, and even water.<ref name="reactions" />
:{{chem2|2 Tb (s) + 3 H2SO4 → 2 Tb(3+) + 3 SO4(2-) + 3 H2↑}}
:{{chem2|1=2 Tb + 3 X2 → 2 TbX3 (X = [[Chemistry:Fluorine|F]], [[Chemistry:Chlorine|Cl]], [[Chemistry:Bromine|Br]], [[Chemistry:Iodine|I]])}}
:{{chem2|2 Tb (s) + 6 H2O → 2 Tb(OH)3 + 3 H2↑}}
Terbium also oxidizes readily in air to form a mixed [[Chemistry:Terbium(III,IV) oxide|terbium(III,IV) oxide]]:<ref name="reactions">{{cite web| url =https://www.webelements.com/terbium/chemistry.html| title =Chemical reactions of Terbium| publisher=Webelements| access-date=2009-06-06}}</ref>
:{{chem2|8 Tb + 7 O2 → 2 Tb4O7}}

The most common oxidation state of terbium is +3 (trivalent), such as {{chem|Tb||Cl|3}}. In the solid state, tetravalent terbium is also known, in compounds such as {{chem2|TbO2}} and {{chem2|TbF4}}.<ref>{{cite journal|title=Higher Oxides of the Lanthanide Elements: Terbium Dioxide|author=Gruen, D. M. |author2=Koehler, W. C. |author3=Katz, J. J. |date=April 1951|pages=1475–1479|volume=73|journal=Journal of the American Chemical Society|doi=10.1021/ja01148a020|issue=4}}</ref> In solution, terbium typically forms trivalent species, but can be oxidized to the tetravalent state with [[Chemistry:Ozone|ozone]] in highly basic aqueous conditions.<ref>{{cite journal |title=Stabilization of Praseodymium(IV) and Terbium(IV) in Aqueous Carbonate Solution |author1=Hobart, D. E. |author2= Samhoun, K. |author3= Young, J. P. |author4=Norvell, V. E. |author5= Mamantov, G. |author6= Peterson, J. R. |date=1980 |pages=321–328 |volume=16 |journal=Inorganic and Nuclear Chemistry Letters |doi=10.1016/0020-1650(80)80069-9 |issue=5}}</ref>

The coordination and organometallic chemistry of terbium is similar to other lanthanides. In aqueous conditions, terbium can be coordinated by nine [[Chemistry:Water|water]] molecules, which are arranged in a [[Physics:Tricapped trigonal prismatic molecular geometry|tricapped trigonal prismatic molecular geometry]]. Complexes of terbium with lower coordination number are also known, typically with bulky ligands like [[Chemistry:Metal bis(trimethylsilyl)amides|bis(trimethyl-silylamide)]], which forms the three-coordinate {{chem2|Tb[N(SiMe3)2]3}} complex.

Most coordination and organometallic complexes contain terbium in the trivalent oxidation state.
Divalent (Tb<sup>2+</sup>) complexes are also known, usually with bulky cyclopentadienyl-type ligands.<ref>{{cite journal |title=Tetramethylcyclopentadienyl Ligands Allow Isolation of Ln(II) Ions across the Lanthanide Series in [K(2.2.2-cryptand)][(C5Me4H)3Ln] Complexes |author1=Jenkins, T. F. |author2= Woen, D. H |author3= Mohanam, L. N. |author4=Ziller, J. W. |author5=Furche, F. |author6=Evans, W. J. |date=2018|pages=3863–3873|volume=141 |journal=Organometallics |doi=10.1021/acs.organomet.8b00557 |issue=21|s2cid=105379627 }}</ref><ref>{{cite journal |title=Completing the Series of +2 Ions for the Lanthanide Elements: Synthesis of Molecular Complexes of Pr2+, Gd2+, Tb2+, and Lu2+ |author1=Macdonald, M. R. |author2= Bates, J. E. |author3= Ziller, J. W. |author4=Furche, F. |author5=Evans, W. J. |date=2013|pages=9857–9868|volume=135|journal=Journal of the American Chemical Society|doi=10.1021/ja403753j|issue=21|pmid=23697603 }}</ref><ref>{{Cite journal|last1=Gould|first1=C. A.|last2=McClain|first2=K. R. |last3=Yu|first3=J. M.|last4=Groshens|first4=T. J.|last5=Furche|first5=F. P.|last6=Harvey|first6=B. G.|last7=Long|first7=J. R.|date=2019-08-21|title=Synthesis and Magnetism of Neutral, Linear Metallocene Complexes of Terbium(II) and Dysprosium(II)|journal=Journal of the American Chemical Society|volume=141|issue=33|pages=12967–12973|doi=10.1021/jacs.9b05816|pmid=31375028|s2cid=199388151|issn=0002-7863}}</ref> A few coordination compounds containing terbium in its tetravalent state are also known.<ref>{{cite journal |title=Molecular Complex of Tb in the +4 Oxidation State |author1=Palumbo, C. T. |author2=Zivkovic, I. |author3=Scopelliti, R. |author4=Mazzanti, M. |date=2019 |pages=9827–9831 |volume=141 |journal=Journal of the American Chemical Society |doi=10.1021/jacs.9b05337 |pmid=31194529 |issue=25 |s2cid=189814301 |url=http://infoscience.epfl.ch/record/268286/files/Palumbo%20ja-2019-05337d%20manuscriptR1.pdf }}{{Dead link|date=April 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{Cite journal|last1=Rice|first1=N. T.|last2=Popov|first2=I. A.|last3=Russo|first3=D. R.|last4=Bacsa|first4=J.|last5=Batista|first5=E. R.|last6=Yang|first6=P.|last7=Telser|first7=J.|last8=La Pierre|first8=H. S.|date=2019-08-21|title=Design, Isolation, and Spectroscopic Analysis of a Tetravalent Terbium Complex|journal=Journal of the American Chemical Society|volume=141|issue=33|pages=13222–13233|doi=10.1021/jacs.9b06622|pmid=31352780|osti=1558225|s2cid=207197096|issn=0002-7863|url=https://figshare.com/articles/journal_contribution/9450461 }}</ref><ref>{{cite journal |title= Stabilization of the Oxidation State + IV in Siloxide-Supported Terbium Compounds |author1=Willauer, A. R. |author2=Palumbo, C. T. |author3=Scopelliti, R. |author4=Zivkovic, I. |author5=Douair, I. |author6=Maron, L.  |author7=Mazzanti, M. |date=2020 |pages=3549–3553|volume=59 |journal=Angewandte Chemie International Edition |issue=9 |doi=10.1002/anie.201914733|pmid=31840371 |s2cid=209385870 |url=https://infoscience.epfl.ch/record/275738/files/Mazzanti_et_al-2019-Angewandte_Chemie_International_Edition-2.pdf }}</ref>

==== Oxidation states ====
Like most rare-earth elements and lanthanides, terbium is usually found in the +3 oxidation state. Like [[Chemistry:Cerium|cerium]] and [[Chemistry:Praseodymium|praseodymium]], terbium can also form a +4 oxidation state, although it is unstable in water.<ref>{{Greenwood&Earnshaw2nd}}</ref> However, it is possible for terbium to also be found in the 0, +1 and +2 oxidation states.

=== Compounds ===
{{Main article|Chemistry:Terbium compounds}}
{{multiple image | direction = vertical | width = 200
|align=right
|image1=Tb-sulfate.jpg
|image2=Tb-sulfate-luminescence.jpg
|caption2=Terbium sulfate, {{chem2|Tb2(SO4)3}} (top), fluoresces green under ultraviolet light (bottom)}}

Terbium combines with nitrogen, carbon, sulfur, phosphorus, boron, selenium, silicon and arsenic at elevated temperatures, forming various binary compounds such as {{chem2|TbH2}}, {{chem2|TbH3}}, {{chem2|TbB2}}, {{chem2|Tb2S3}}, {{chem2|TbSe}}, {{chem2|TbTe}} and {{chem2|TbN}}.<ref name="patnaik" /> In those compounds, Tb mostly exhibits the oxidation states +3 and sometimes +2. Terbium(II) halides are obtained by [[Physics:Annealing (materials science)|annealing]] Tb(III) halides in presence of metallic Tb in [[Chemistry:Tantalum|tantalum]] containers. Terbium also forms sesquichloride {{chem2|Tb2Cl3}}, which can be further reduced to TbCl by annealing at 800&nbsp;°C. This terbium(I) chloride forms platelets with layered graphite-like structure.<ref>{{cite book| page=1128| url=https://books.google.com/books?id=U3MWRONWAmMC&pg=PA1128| title =Advanced inorganic chemistry| edition =6th| author= Cotton| publisher= Wiley-India| date = 2007| isbn =978-81-265-1338-3}}</ref>

[[Chemistry:Terbium(IV) fluoride|Terbium(IV) fluoride]] is the only halide that tetravalent terbium can form, and has strong oxidizing properties. It is also a strong [[Chemistry:Halogenation|fluorinating agent]], emitting relatively pure atomic [[Chemistry:Fluorine|fluorine]] when heated, rather than the mixture of fluoride vapors emitted from [[Chemistry:Cobalt(III) fluoride|cobalt(III) fluoride]] or [[Chemistry:Cerium(IV) fluoride|cerium(IV) fluoride]].<ref>{{cite journal |last1=Rau |first1=J. V. |last2=Chilingarov |first2=N. S. |last3=Leskiv |first3=M. S. |last4=Sukhoverkhov |first4=V. F. |last5=Rossi Albertini |first5=V. |last6=Sidorov |first6=L. N. |title=Transition and rare earth metal fluorides as thermal sources of atomic and molecular fluorine |journal=Le Journal de Physique IV |date=August 2001 |volume=11 |issue=PR3 |pages=Pr3–109–Pr3-113 |doi=10.1051/jp4:2001314}}</ref> It can be obtained by reacting [[Chemistry:Terbium(III) chloride|terbium(III) chloride]] or [[Chemistry:Terbium(III) fluoride|terbium(III) fluoride]] with [[Chemistry:Fluorine|fluorine]] gas at 320&nbsp;°C:<ref>{{Cite book|author=G. Meyer |author2=Lester R. Morss |title= Synthesis of Lanthanide and Actinide Compounds. |publisher=Springer Science & Business Media|year= 1991|page=60|isbn= 978-0-7923-1018-1 |url = https://books.google.com/books?id=bnS5elHL2w8C&pg=PA60}}</ref>
: 2 TbF<sub>3</sub> + F<sub>2</sub> → 2 TbF<sub>4</sub>
When TbF<sub>4</sub> and [[Chemistry:Caesium fluoride|CsF]] is mixed in a stoichiometric ratio, in a fluorine gas atmosphere, CsTbF<sub>5</sub> is obtained. It is an [[Physics:Orthorhombic crystal system|orthorhombic]] crystal, with [[Space group|space group]] ''Cmca'', with a layered structure composed of [TbF<sub>8</sub>]<sup>4−</sup> and 11-coordinated Cs<sup>+</sup>.<ref>{{cite journal|last1=Gaumet|first1=V.|last2=Avignant|first2=D.|title=Caesium Pentafluoroterbate, CsTbF<sub>5</sub>|journal=Acta Crystallographica Section C: Crystal Structure Communications|volume=53|issue=9|year=1997|pages=1176–1178 |doi=10.1107/S0108270197005556|bibcode=1997AcCrC..53.1176G }}</ref> The compound BaTbF<sub>6</sub> can be prepared in a similar method. It is an orthorhombic crystal, with space group ''Cmma''. The compound [TbF<sub>8</sub>]<sup>4−</sup> also exists.<ref>{{cite journal|last1=Largeau|first1=E.|last2=El-Ghozzi|first2=M.|last3=Métin|first3=J.|last4=Avignant|first4=D.|title=β-BaTbF6|journal=Acta Crystallographica Section C: Crystal Structure Communications|volume=53|issue=5|year=1997|pages=530–532 |doi=10.1107/S0108270196014527|bibcode=1997AcCrC..53..530L }}</ref>

Other compounds include 
* [[Chemistry:Chloride|Chloride]]s: {{chem2|[[Chemistry:Terbium(III) chloride|TbCl3]]}}
* [[Chemistry:Bromide|Bromide]]s: {{chem2|[[Chemistry:Terbium(III) bromide|TbBr3]]}}
* [[Chemistry:Iodide|Iodide]]s: {{chem2|[[Chemistry:Terbium(III) iodide|TbI3]]}}
* [[Chemistry:Fluoride|Fluoride]]s: {{chem2|[[Chemistry:Terbium(III) fluoride|TbF3]]}}, {{chem2|[[Chemistry:Terbium(IV) fluoride|TbF4]]}}

=== Isotopes ===
{{Main|Physics:Isotopes of terbium}}
Naturally occurring terbium is composed of its only stable [[Physics:Isotope|isotope]], terbium-159; the element is thus [[Mononuclidic element|mononuclidic]] and [[Monoisotopic element|monoisotopic]]. Thirty-six radioisotopes have been characterized, with the heaviest being terbium-171 (with an [[Physics:Atomic mass|atomic mass]] of 170.95330(86) [[Dalton (unit)|u]]) and lightest being terbium-135 (exact mass unknown).{{NUBASE2016|ref}} The most stable [[Physics:Synthetic radioisotope|synthetic radioisotope]]s of terbium are terbium-158, with a [[Physics:Half-life|half-life]] of 180 years, and terbium-157, with a half-life of 71 years. All of the remaining [[Physics:Radioactive|radioactive]] isotopes have half-lives that are much less than a quarter of a year, and the majority of these have half-lives that are less than half a minute.{{NUBASE2016|ref}} The primary decay mode before the most abundant stable isotope, <sup>159</sup>Tb, is [[Physics:Electron capture|electron capture]], which results in production of [[Chemistry:Gadolinium|gadolinium]] isotopes, and the primary mode after is beta minus decay, resulting in [[Chemistry:Dysprosium|dysprosium]] isotopes.{{NUBASE2016|ref}}

The element also has 27 [[Physics:Nuclear isomer|nuclear isomer]]s, with masses of 141–154, 156, and 158 (not every mass number corresponds to only one isomer). The most stable of them are terbium-156m, with a half-life of 24.4 hours, and terbium-156m2, with a half-life of 22.7 hours; this is longer than half-lives of most ground states of radioactive terbium isotopes, except those with mass numbers 155–161.{{NUBASE2016|ref}}

Terbium-149, with a half-life of 4.1 hours, is a promising candidate in targeted alpha therapy and [[Physics:Positron emission tomography|positron emission tomography]].<ref>{{cite journal | last1=Müller | first1=Cristina | last2=Vermeulen | first2=Christiaan | last3=Köster | first3=Ulli | last4=Johnston | first4=Karl | last5=Türler | first5=Andreas | last6=Schibli | first6=Roger | last7=van der Meulen | first7=Nicholas P. | title=Alpha-PET with terbium-149: evidence and perspectives for radiotheragnostics | journal=EJNMMI Radiopharmacy and Chemistry | publisher=Springer Science and Business Media LLC | volume=1 | issue=1 | date=2016-03-28 | page=5 | issn=2365-421X | doi=10.1186/s41181-016-0008-2| pmid=29564382 | pmc=5843804 | doi-access=free }}</ref><ref>{{cite journal | last1=Eychenne | first1=Romain | last2=Chérel | first2=Michel | last3=Haddad | first3=Férid | last4=Guérard | first4=François | last5=Gestin | first5=Jean-François | title=Overview of the Most Promising Radionuclides for Targeted Alpha Therapy: The "Hopeful Eight" | journal=Pharmaceutics | publisher=MDPI AG | volume=13 | issue=6 | date=2021-06-18 | issn=1999-4923 | doi=10.3390/pharmaceutics13060906 | page=906 | pmid=34207408 | pmc=8234975 | doi-access=free }}</ref>

== History ==
[[File:Mosander Carl Gustav bw.jpg|thumb|right|Carl Gustaf Mosander, the scientist who discovered terbium, lanthanum and erbium.]]
Swedish [[Chemist|chemist]] [[Biography:Carl Gustaf Mosander|Carl Gustaf Mosander]] discovered terbium in 1843. He detected it as an impurity in yttrium oxide, {{chem2|Y2O3}}. Yttrium is named after the village of [[Chemistry:Ytterby|Ytterby]] in Sweden. Terbium was not isolated in pure form until the advent of [[Chemistry:Ion exchange|ion exchange]] techniques.<ref name="James">{{cite book |last1=Marshall |first1=James L. |last2=Marshall |first2=Virginia R. |title=Science history: a traveler's guide|chapter=Northern Scandinavia: An Elemental Treasure Trove |date=October 31, 2014 |publisher=ACS Symposium Series|volume= 1179 |isbn=978-0-8412-3020-0 |pages=209–257 |doi=10.1021/bk-2014-1179.ch011 }}</ref><ref name="history" /><ref name="Weeks">{{cite book |last1=Weeks |first1=Mary Elvira |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |location=Easton, PA |url=https://archive.org/details/discoveryoftheel002045mbp |edition=6th }}</ref>{{rp|701}}<ref name="XVI">{{cite journal | author = Weeks, Mary Elvira | title = The discovery of the elements: XVI. The rare earth elements | journal = Journal of Chemical Education | year = 1932 | volume = 9 | issue = 10 | pages = 1751&ndash;1773 | doi = 10.1021/ed009p1751 | bibcode=1932JChEd...9.1751W}}</ref><ref name="James" /><ref name="Beginnings">{{cite journal |last1=Marshall |first1=James L. Marshall |last2=Marshall |first2=Virginia R. Marshall |title=Rediscovery of the elements: The Rare Earths–The Beginnings |journal=The Hexagon |date=2015 |pages=41–45 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/rare%20earths%20I.pdf |access-date=30 December 2019}}</ref><ref name="Virginia">{{cite journal |last1=Marshall |first1=James L. Marshall |last2=Marshall |first2=Virginia R. Marshall |title=Rediscovery of the elements: The Rare Earths–The Confusing Years |journal=The Hexagon |date=2015 |pages=72–77 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/rare%20earths%20II.pdf |access-date=30 December 2019}}</ref>

Mosander first separated yttria into three fractions, all named for the ore: yttria, erbia, and terbia. "Terbia" was originally the fraction that contained the pink color, due to the element now known as [[Chemistry:Erbium|erbium]]. "Erbia" (containing what is now known as terbium) originally was the fraction that was essentially colorless in solution. The insoluble oxide of this element was noted to be tinged brown.

Later workers had difficulty in observing the minor colorless "erbia", but the soluble pink fraction was impossible to miss. Arguments went back and forth as to whether erbia even existed. In the confusion, the original names got reversed, and the exchange of names stuck, so that the pink fraction referred eventually to the solution containing erbium (which in solution, is pink). It is now thought that workers using double sodium or [[Chemistry:Potassium sulfate|potassium sulfate]]s to remove ceria from yttria inadvertently lost the terbium into the ceria-containing precipitate. What is now known as terbium was only about 1% of the original yttria, but that was sufficient to impart a yellowish color to the yttrium oxide. Thus, terbium was a minor component in the original fraction containing it, where it was dominated by its immediate neighbors, [[Chemistry:Gadolinium|gadolinium]] and [[Chemistry:Dysprosium|dysprosium]].

Thereafter, whenever other rare earths were teased apart from this mixture, whichever fraction gave the brown oxide retained the terbium name, until at last, the brown oxide of terbium was obtained in pure form. The 19th century investigators did not have the benefit of the UV fluorescence technology to observe the brilliant yellow or green Tb(III) fluorescence that would have made terbium easier to identify in solid mixtures or solutions.<ref name="history">{{cite book| page = 5| url=https://books.google.com/books?id=E1npz8pwmYwC&pg=PA5| title =Extractive metallurgy of rare earths| author =Gupta, C. K. | author2 =Krishnamurthy, Nagaiyar | publisher=CRC Press| date = 2004| isbn =978-0-415-33340-5}}</ref>

== Occurrence ==
[[Image:Xenotim mineralogisches museum bonn.jpg|thumb|Xenotime]]
Terbium is contained along with other rare earth elements in many minerals, including [[Chemistry:Monazite|monazite]] ({{chem2|(Ce,La,Th,Nd,Y)PO4}} with up to 0.03% terbium), [[Chemistry:Xenotime|xenotime]] ({{chem2|YPO4}}) and [[Chemistry:Euxenite|euxenite]] ({{chem2|(Y,Ca,Er,La,Ce,U,Th)(Nb,Ta,Ti)2O6}} with 1% or more terbium). The crust abundance of terbium is estimated as 1.2&nbsp;mg/kg.<ref name="patnaik">{{cite book | last =Patnaik | first =Pradyot | date = 2003 | title =Handbook of Inorganic Chemical Compounds | publisher = McGraw-Hill | pages = 920–921| isbn =978-0-07-049439-8 | url= https://books.google.com/books?id=Xqj-TTzkvTEC&pg=PA243 | access-date = 2009-06-06}}</ref> No terbium-dominant mineral has yet been found.<ref>
{{cite web |url=https://www.mindat.org/ |title=Mindat.org |author=Hudson Institute of Mineralogy |date=1993–2018 |website=www.mindat.org |access-date=14 January 2018}}</ref>

Currently, the richest commercial sources of terbium are the ion-adsorption [[Earth:Clay|clay]]s of southern China; the concentrates with about two-thirds yttrium oxide by weight have about 1% terbia. Small amounts of terbium occur in [[Chemistry:Bastnäsite|bastnäsite]] and monazite; when these are processed by solvent extraction to recover the valuable heavy lanthanides as [[Chemistry:Samarium|samarium]]-[[Chemistry:Europium|europium]]-[[Chemistry:Gadolinium|gadolinium]] concentrate, terbium is recovered therein. Due to the large volumes of bastnäsite processed relative to the ion-adsorption clays, a significant proportion of the world's terbium supply comes from bastnäsite.<ref name="CRC" />

In 2018, a rich terbium supply was discovered off the coast of {{wipe|Japan}}'s Minamitori Island, with the stated supply being "enough to meet the global demand for 420 years".<ref name="Takaya Yasukawa Kawasaki Fujinaga 2018 p.">{{cite journal | last1=Takaya | first1=Yutaro | last2=Yasukawa | first2=Kazutaka | last3=Kawasaki | first3=Takehiro | display-authors=0 | title=The tremendous potential of deep-sea mud as a source of rare-earth elements | journal=Scientific Reports | volume=8 | issue=1 | date=2018-04-10 | issn=2045-2322 | doi=10.1038/s41598-018-23948-5 | page=5763| pmid=29636486 | pmc=5893572 | bibcode=2018NatSR...8.5763T }}</ref>

== Production ==
Crushed terbium-containing minerals are treated with hot concentrated [[Chemistry:Sulfuric acid|sulfuric acid]] to produce water-soluble sulfates of rare earths. The acidic filtrates are partially neutralized with caustic soda to pH 3–4. [[Chemistry:Thorium|Thorium]] precipitates out of solution as hydroxide and is removed. After that the solution is treated with [[Chemistry:Ammonium oxalate|ammonium oxalate]] to convert rare earths into their insoluble [[Chemistry:Oxalate|oxalate]]s. The oxalates are decomposed to oxides by heating. The oxides are dissolved in [[Chemistry:Nitric acid|nitric acid]] that excludes one of the main components, cerium, whose oxide is insoluble in {{chem2|HNO3}}. Terbium is separated as a [[Chemistry:Double salt|double salt]] with [[Chemistry:Ammonium nitrate|ammonium nitrate]] by crystallization.<ref name="patnaik" />

The most efficient separation routine for terbium salt from the rare-earth salt solution is [[Chemistry:Ion exchange|ion exchange]]. In this process, rare-earth ions are [[Chemistry:Adsorption|sorbed]] onto suitable ion-exchange resin by exchange with hydrogen, ammonium or cupric ions present in the resin. The rare earth ions are then selectively washed out by suitable complexing agents. As with other rare earths, terbium metal is produced by reducing the anhydrous chloride or fluoride with calcium metal. Calcium and [[Chemistry:Tantalum|tantalum]] impurities can be removed by vacuum remelting, distillation, amalgam formation or [[Physics:Zone melting|zone melting]].<ref name="patnaik" />

== Applications ==
Terbium is used as a [[Chemistry:Dopant|dopant]] in [[Chemistry:Calcium fluoride|calcium fluoride]], calcium [[Chemistry:Tungstate|tungstate]], and [[Chemistry:Strontium|strontium]] [[Chemistry:Molybdate|molybdate]], materials that are used in solid-state devices, and as a crystal stabilizer of [[Physics:Fuel cell|fuel cell]]s which operate at elevated temperatures, together with {{chem2|[[Chemistry:Zirconium(IV) oxide|ZrO2]]}}.<ref name="CRC">{{cite book | editor = Lide, D. R. | title = CRC Handbook of Chemistry and Physics | edition = 86th | location = Boca Raton (FL) | publisher = CRC Press | year = 2005 | isbn = 978-0-8493-0486-6 |author=Hammond, C. R. |chapter=The Elements}}</ref>

Terbium is also used in [[Chemistry:Alloy|alloy]]s and in the production of electronic devices. As a component of [[Chemistry:Terfenol-D|Terfenol-D]], terbium is used in [[Engineering:Actuator|actuator]]s, in naval sonar systems, [[Engineering:Sensor|sensor]]s, in the [[Engineering:SoundBug|SoundBug]] device (its first commercial application), and other magnetomechanical devices. Terfenol-D is a terbium alloy that expands or contracts in the presence of a magnetic field. It has the highest [[Physics:Magnetostriction|magnetostriction]] of any [[Chemistry:Alloy|alloy]].<ref>{{cite journal|doi=10.1016/j.sna.2008.11.026|title=New elastomer–Terfenol-D magnetostrictive composites|date=2009|author=Rodriguez, C|journal=Sensors and Actuators A: Physical|volume=149|page=251|last2=Rodriguez|first2=M.|last3=Orue|first3=I.|last4=Vilas|first4=J.|last5=Barandiaran|first5=J.|last6=Gubieda|first6=M.|last7=Leon|first7=L.|issue=2}}</ref>

Terbium [[Chemistry:Oxide|oxide]] is used in green [[Physics:Phosphor|phosphor]]s in fluorescent lamps and color TV tubes. [[Chemistry:Sodium|Sodium]] terbium [[Physics:Borate|borate]] is used in solid state devices. The brilliant fluorescence allows terbium to be used as a probe in biochemistry, where it somewhat resembles [[Chemistry:Calcium|calcium]] in its behavior. Terbium "green" phosphors (which fluoresce a brilliant lemon-yellow) are combined with divalent europium blue phosphors and trivalent europium red phosphors to provide the trichromatic lighting technology which is by far the largest consumer of the world's terbium supply. Trichromatic lighting provides much higher light output for a given amount of electrical energy than does incandescent lighting.<ref name="CRC" />

Terbium is also used to detect endospores, as it acts as an assay of [[Chemistry:Dipicolinic acid|dipicolinic acid]] based on [[Physics:Photoluminescence|photoluminescence]].<ref>{{cite journal|last1=Rosen|first1=D. L.|last2=Sharpless|first2=C.|last3=McGown|first3=L. B.|title=Bacterial Spore Detection and Determination by Use of Terbium Dipicolinate Photoluminescence|journal=Analytical Chemistry|date=1997|volume=69|issue=6|pages=1082–1085|doi=10.1021/ac960939w}}</ref>

In 2023, terbium compounds were used to create a lattice with one [[Chemistry:Iron|iron]] (Fe) atom, that was then examined by [[Physics:Synchrotron|synchrotron]] [[Physics:X-ray|x-ray]] beam, to examine one atom at sub-atomic levels for the first time.<ref name="2023-05-31_Nature">{{Cite journal |last1=Ajayi |first1=Tolulope M. |last2=Shirato |first2=Nozomi |last3=Rojas |first3=Tomas |last4=Wieghold |first4=Sarah |last5=Cheng |first5=Xinyue |last6=Latt |first6=Kyaw Zin |last7=Trainer |first7=Daniel J. |last8=Dandu |first8=Naveen K. |last9=Li |first9=Yiming |last10=Premarathna |first10=Sineth |last11=Sarkar |first11=Sanjoy |last12=Rosenmann |first12=Daniel |last13=Liu |first13=Yuzi |last14=Kyritsakas |first14=Nathalie |last15=Wang |first15=Shaoze |date=June 2023 |title=Characterization of just one atom using synchrotron X-rays |url=https://www.nature.com/articles/s41586-023-06011-w |journal=Nature |language=en |volume=618 |issue=7963 |pages=69–73 |doi=10.1038/s41586-023-06011-w |pmid=37259001 |bibcode=2023Natur.618...69A |s2cid=258992110 |issn=1476-4687}}</ref>

== Precautions ==
Handling of terbium, like other lanthanides, should be done with care. Terbium compounds show moderate toxicity, although there is limited data on the specific toxicity of the element. They can act as irritants to the skin and eyes upon contact. Ingestion of terbium compounds should be avoided due to their mildly toxic nature.<ref name="vedantu">{{Cite web |title=Harmful Effects of Terbium |url=https://www.vedantu.com/chemistry/terbium |access-date=2023-11-07 |website=Vedantu}}</ref><ref name="lanl">{{Cite web |title=Terbium |url=https://periodic.lanl.gov/65.shtml |access-date=2023-11-07 |website=Los Alamos National Laboratory}}</ref>

In the event of exposure:

* If inhaled: Move the person to fresh air, provide artificial respiration if breathing has stopped, and seek medical advice.
* In case of skin contact: Wash immediately with soap and water, then rinse thoroughly and seek medical advice.
* In case of eye contact: Rinse the eyes for several minutes under running water and consult a physician.
* If swallowed: Seek immediate medical treatment.<ref name="americanelements">{{Cite web |title=Terbium(III,IV) Oxide Safety Data Sheet |url=https://www.americanelements.com/terbium-iii-iv-oxide-12037-01-3 |access-date=2023-11-07 |website=American Elements}}</ref>

For safe handling and storage:

* Keep terbium compounds in tightly sealed containers stored in a cool, dry place away from oxidizing agents.
* Use personal protective equipment, such as impervious gloves and safety glasses, to prevent skin and eye contact.
* Ensure adequate ventilation in the working area and avoid releasing terbium compounds into the environment without proper permits.<ref name="americanelementsstorage"/>

Proper disposal of terbium compounds should be conducted in accordance with local environmental regulations.<ref name="sciencemadness">{{Cite web |title=Terbium(III) oxide - Handling and Storage |url=http://www.sciencemadness.org/smwiki/index.php/Terbium(III)_oxide |access-date=2023-11-07 |website=Sciencemadness Wiki}}</ref>

== See also ==
* [[Chemistry:Terbium compounds|Terbium compounds]]
* [[Chemistry:List of elements facing shortage|List of elements facing shortage]]

== References ==
{{Reflist}}

== External links ==
{{Commons|Terbium}}
* [http://www.webelements.com/webelements/elements/text/Tb/index.html WebElements.com&nbsp;– Terbium]
* [http://education.jlab.org/itselemental/ele065.html It's Elemental&nbsp;– Terbium]
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{{Terbium compounds}}


[[Category:Terbium| ]]
[[Category:Chemical elements]]
[[Category:Ferromagnetic materials]]
[[Category:Lanthanides]]
[[Category:Reducing agents]]

{{Sourceattribution|Terbium}}