Editing Terbium (section)

=== Compounds ===
{{Main article|Terbium compounds}}
{{multiple image | direction = vertical | width = 200
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|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|[[terbium(III) nitride|TbN]]}}.<ref name="patnaik" /> In these compounds, terbium mainly exhibits the oxidation state +3, with the +2 state appearing rarely. Terbium(II) halides are obtained by [[annealing (materials science)|annealing]] terbium(III) halides in presence of metallic terbium in [[tantalum]] containers. Terbium also forms the sesquichloride {{chem2|Tb2Cl3}}, which can be further reduced to terbium(I) chloride ({{Chem2|TbCl}}) by annealing at 800&nbsp;°C; this compound 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>

[[Terbium(IV) fluoride]] ({{Chem2|TbF4}}) is the only halide that tetravalent terbium can form. It has strong oxidizing properties and is a strong [[halogenation|fluorinating agent]], emitting relatively pure atomic [[fluorine]] when heated, rather than the mixture of fluoride vapors emitted from [[cobalt(III) fluoride]] or [[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 [[terbium(III) chloride]] or [[terbium(III) fluoride]] with [[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 {{Chem2|TbF4}} and [[caesium fluoride]] (CsF) is mixed in a stoichiometric ratio in a fluorine gas atmosphere, caesium pentafluoroterbate ({{Chem2|CsTbF5}}) is obtained. It is an [[orthorhombic crystal system|orthorhombic]] crystal with [[space group]] ''Cmca'' and 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 barium hexafluoroterbate ({{Chem2|BaTbF6}}), an orthorhombic crystal with space group ''Cmma'', can be prepared in a similar method. The terbium fluoride ion [TbF<sub>8</sub>]<sup>4−</sup><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> also exists in the structure of potassium terbium fluoride crystals.<ref>{{Cite journal |last1=Balodhi |first1=Ashiwini |last2=Chang |first2=Kelvin |last3=Stevens |first3=Kevin T. |last4=Chakrapani |first4=Sunil K. |last5=Ennaceur |first5=Susan M. |last6=Migliori |first6=Albert |last7=Zevalkink |first7=Alexandra |date=2020-10-26 |title=Determination of single crystal elastic moduli of KTb<sub>3</sub>F<sub>10</sub> by resonant ultrasound spectroscopy |url=https://pubs.aip.org/aip/jap/article/128/16/165104/568450/Determination-of-single-crystal-elastic-moduli-of |journal=Journal of Applied Physics |volume=128 |issue=16 |doi=10.1063/5.0024723 |bibcode=2020JAP...128p5104B |issn=0021-8979}}</ref><ref>{{Cite journal |last1=Valiev |first1=Uygun V. |last2=Karimov |first2=Denis N. |last3=Ma |first3=Chong-Geng |last4=Sultonov |first4=Odiljon Z. |last5=Pelenovich |first5=Vasiliy O. |date=2022-11-12 |title=Tb<sup>3+</sup> Ion Optical and Magneto-Optical Properties in the Cubic Crystals KTb<sub>3</sub>F<sub>10</sub> |journal=Materials |language=en |volume=15 |issue=22 |pages=7999 |doi=10.3390/ma15227999 |issn=1996-1944 |pmc=9693278 |pmid=36431487 |doi-access=free|bibcode=2022Mate...15.7999V }}</ref>

[[Terbium(III) oxide]] or terbia is the main oxide of terbium, and appears as a dark brown water-insoluble solid. It is slightly hygroscopic<ref name=":02">{{Cite book |last1=Larrañaga |first1=Michael D. |url=https://onlinelibrary.wiley.com/doi/book/10.1002/9781119312468 |title=Hawley's Condensed Chemical Dictionary |last2=Lewis |first2=Richard J. |last3=Lewis |first3=Robert A. |date=September 2016 |publisher=Wiley |isbn=978-1-118-13515-0 |edition=16th |pages=1310 |language=en |doi=10.1002/9781119312468}}</ref> and is the main terbium compound found in rare earth-containing minerals and clays.<ref name=":2" />

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