Indium: Difference between revisions

'''Indium''' is a [[chemical element]]; withit thehas [[Symbol (chemistry)|symbol]] '''In''' and [[atomic number]] 49. Indium is the softest metal that is not an [[alkali metal]]. It is a silvery-white metal that resembles [[tin]] in appearance. It is a [[post-transition metal]] thatand makes up 0.21 [[parts per million]]one of the Earth's crust. Indium has a melting point higher than [[sodium]] and [[gallium]], but lower than [[lithium]] andsoftest tinelements. Chemically, indium is similar to [[gallium]] and [[thallium]], and itits isproperties are largely intermediate between the two in terms of its properties.<ref name="Ph.D.Lide2010">{{cite book |author1=W. M. Haynes |editorurl=David Rhttps://archive.org/details/crchandbookofche00davi Lide|title=CRC Handbook of Chemistry and Physics: A Ready-reference Book of Chemical and Physical Data|url=https://archive.org/details/crchandbookofche00davi|url-access=registration |date=2010 |publisher=CRC Press |isbn=978-1-4398-2077-3 |editor=David R. Lide |url-access=registration}}</ref> IndiumIt was discovered in 1863 by [[Ferdinand Reich]] and [[Hieronymous Theodor Richter]] by [[spectroscope|spectroscopic methods]]. Theyand named it for the [[indigo]] blue line in its spectrum.<ref Indiumname="Venetskii" was isolated the next year./>

Indium has no biological role. Itsand its compounds are toxic when inhaled or injected into the bloodstream. Most occupational exposure is through ingestion, fromalthough which indium compoundsthey are notpoorly absorbed well,following andingestion.<ref inhalation,name="Sauler" from/><ref whichname="toxic" they are moderately absorbed./>

Indium is a shiny silvery-white, highly [[ductile]] [[post-transition metal]] with a bright [[Lustre (mineralogy)|luster]].<ref name="InProcess">{{cite journal|last=Alfantazi|first=A. M.|date=2003|title=Processing of indium: a review|journal=Minerals Engineering|volume=16|issue=8|pages=687–694|doi=10.1016/S0892-6875(03)00168-7|author2=Moskalyk, R. R.|bibcode=2003MiEng..16..687A }}</ref> It is so soft ([[Mohs hardness]] 1.2) that like sodium, it can be cut with a knife. It alsoand leaves a visible line like a pencil when rubbed on paper.<ref name="Binder">{{cite book |last=Binder |first=Harry H. |date=1999 |title=Lexicon der chemischen Elemente |publisher=S. Hirzel Verlag |isbn=978-3-7776-0736-8 |language=de }}</ref> It is a member of [[boron group|group 13]] on the [[periodic table]] and its properties are mostly intermediate between its vertical neighboursneighbors [[gallium]] and [[thallium]]. Like [[tin]], a high-pitched [[tin cry|cry]] is heard when indium is bent – a crackling sound due to [[crystal twinning]].<ref name="InProcess" /> Like gallium, indium is able to [[wetting|wet]] glass. Like both, indium has a low [[melting point]], 156.60&nbsp;°C (313.88&nbsp;°F); higher than its lighter homologue, gallium, but lower than its heavier homologue, thallium, and lower than tin.<ref name="Lange">{{cite book |last=Dean |first=John A. |title=Lange's handbook of chemistry |publisher=McGraw-Hill, Inc.|date=523|isbn=978-0-07-016190-0|edition=Fifteenth }}</ref> The boiling point is 2072&nbsp;°C (3762&nbsp;°F), higher than that of thallium, but lower than gallium, conversely to the general trend of melting points, but similarly to the trends down the other post-transition metal groups because of the weakness of the metallic bonding with few [[Delocalized electron|electrons delocalized]].<ref name="Greenwood222">Greenwood and Earnshaw, p. 222</ref>

The density of indium, 7.31&nbsp;g/cm³, is also greater than gallium, but lower than thallium. Below the [[critical temperature]], 3.41&nbsp;[[kelvin|K]], indium becomes a [[superconductor]]. Indium crystallizes in the body-centered [[tetragonal crystal system]] in the [[space group]] ''I''4/''mmm'' ([[lattice parameter]]s:&nbsp;''a''&nbsp;=&nbsp;325&nbsp;[[picometer|pm]], ''c''&nbsp;=&nbsp;495&nbsp;pm):<ref name="Lange" /> this is a slightly distorted [[face-centered cubic]] structure, where each indium atom has four neighbours at 324&nbsp;pm distance and eight neighbours slightly further (336&nbsp;pm).<ref name="Greenwood252">Greenwood and Earnshaw, p. 252</ref> Indium has greater solubility in liquid mercury than any other metal (more than 50 mass percent of indium at 0&nbsp;°C).<ref>{{Cite journal|title=Hg-In phase diagram|journal=Journal of Phase Equilibria and Diffusion|volume=33|issue=2|pages=159–160|doi=10.1007/s11669-012-9993-3|year=2012|last1=Okamoto|first1=H.|s2cid=93043767}}</ref> Indium displays a ductile [[Viscoplasticity|viscoplastic]] response, found to be size-independent in tension and compression. However it does have a [[Size effect on structural strength|size effect]] in bending and indentation, associated to a length-scale of order 50–100&nbsp;µmμm,<ref>{{Cite journal|last1=Iliev|first1=S. P.|last2=Chen|first2=X.|last3=Pathan|first3=M. V.|last4=Tagarielli|first4=V. L.|date=2017-01-23|title=Measurements of the mechanical response of Indium and of its size dependence in bending and indentation|journal=Materials Science and Engineering: A|volume=683|pages=244–251|doi=10.1016/j.msea.2016.12.017|hdl=10044/1/43082|hdl-access=free}}</ref> significantly large when compared with other metals.

Indium has 49 electrons, with an electronic configuration of &#91;[[krypton|Kr]]&#93;4d¹⁰5s²5p¹. In compounds, indium most commonly donates the three outermost electrons to become indium(III), In³⁺. In some cases, the pair of 5s-electrons are not donated, resulting in indium(I), In⁺. The stabilization of the [[valence (chemistry)|monovalent]] state is attributed to the [[inert pair effect]], in which [[relativistic quantum chemistry|relativistic effects]] stabilize the 5s-orbital, observed in heavier elements. Thallium (indium's heavier [[homologyHomologous (chemistry)series|homolog]]) shows an even stronger effect, causing [[Redox|oxidation]] to thallium(I) to be more probable than to thallium(III),<ref>{{cite book|publisher = Walter de Gruyter|date = 1985|edition = 91–100|pages = 892–893|isbn = 978-3-11-007511-3|title = Lehrbuch der Anorganischen Chemie|first = Arnold F.|last = Holleman|author2 = Wiberg, Egon |author3 = Wiberg, Nils|chapter =Thallium|language=de}}</ref> whereas gallium (indium's lighter homolog) commonly shows only the +3 oxidation state. Thus, although thallium(III) is a moderately strong [[oxidizing agent]], indium(III) is not, and many indium(I) compounds are powerful [[reducing agent]]s.<ref name="G&E">{{Greenwood&Earnshaw2nd}}</ref> While the energy required to include the s-electrons in chemical bonding is lowest for indium among the group 13 metals, bond energies decrease down the group so that by indium, the energy released in forming two additional bonds and attaining the +3 state is not always enough to outweigh the energy needed to involve the 5s-electrons.<ref name="Greenwood256">Greenwood and Earnshaw, p. 256</ref> Indium(I) oxide and hydroxide are more basic and indium(III) oxide and hydroxide are more acidic.<ref name="Greenwood256" />

Indium has 39 known [[isotope]]s, ranging in [[mass number]] from 97 to 135. Only two isotopes occur naturally as [[primordial nuclide]]s: indium-113, the only [[stable isotope]], and indium-115, which has a [[half-life]] of 4.41{{e|14}} years, four orders of magnitude greater than the [[age of the Universe]] and nearly 30,000 times greater than half life of [[thorium-232]].<ref name="Audi">{{NUBASE 2003}}</ref> The half-life of ¹¹⁵In is very long because the [[beta decay]] to ¹¹⁵[[tin|Sn]] is [[selection rule|spin-forbidden]].<ref>{{cite journal |last1=Dvornický |first1=R. |last2=Šimkovic |first2=F. |date=13–16 June 2011 |title=Second unique forbidden β decay of ¹¹⁵In and neutrino mass |journal=AIP Conf. Proc. |volume=1417 |issue=33 |pagespage=33 |doi=10.1063/1.3671032|series=AIP Conference Proceedings |bibcode=2011AIPC.1417...33D }}</ref> Indium-115 makes up 95.7% of all indium. Indium is one of three known elements (the others being [[tellurium]] and [[rhenium]]) of which the stable isotope is less abundant in nature than the long-lived primordial radioisotopes.<ref>{{cite web |url=http://www.ciaaw.org/pubs/Periodic_Table_Isotopes.pdf |title=IUPAC Periodic Table of the Isotopes |date=1 October 2013 |website=ciaaw.org |publisher=[[IUPAC]] |access-date=21 June 2016 |archive-date=14 February 2019 |archive-url=https://web.archive.org/web/20190214115238/http://www.ciaaw.org/pubs/Periodic_Table_Isotopes.pdf |url-status=live }}</ref>

The stablest [[synthetic radioisotope|artificial]] isotope is [[indium-111]], with a half-life of approximately 2.8&nbsp;days. All other isotopes have half-lives shorter than 5 hours. Indium also has 47 meta states, among which indium-114m1 (half-life about 49.51&nbsp;days) is the most stable, more stable than the ground state of any indium isotope other than the primordial. All decay by [[isomeric transition]]. The indium isotopes lighter than ¹¹⁵¹¹³In predominantly decay through [[electron capture]] or [[positron emission]] to form [[cadmium]] isotopes, while the other indium isotopes fromheavier than ¹¹⁵¹¹³In and greater predominantly decay through beta-minus decay to form tin isotopes.<ref name="Audi" />

{{Category seeSee also|Indium chalcogenides|Category:Indium compounds}}

The analogous sesquichalcogenidessesqui-chalcogenides with [[sulfur]], [[selenium]], and [[tellurium]] are also known.<ref name="Greenwood286">Greenwood and Earnshaw, p. 286</ref> Indium forms the expected [[indium halides|trihalides]]. Chlorination, bromination, and iodination of In produce colorless [[indium(III) chloride|InCl₃]], [[indium(III) bromide|InBr₃]], and yellow InI₃. The compounds are [[Lewis acid]]s, somewhat akin to the better known aluminium trihalides. Again like the related aluminium compound, InF₃ is polymeric.<ref name="Greenwood263">Greenwood and Earnshaw, pp. 263–7</ref>

In 1863, the German chemists [[Ferdinand Reich]] and [[Hieronymous Theodor Richter]] were testing ores from the mines around [[Freiberg, Saxony]]. They dissolved the minerals [[pyrite]], [[arsenopyrite]], [[galena]] and [[sphalerite]] in [[hydrochloric acid]] and distilled raw [[zinc chloride]]. Reich, who was [[color-blind]], employed Richter as an assistant for detecting the colored spectral lines. Knowing that ores from that region sometimes contain [[thallium]], they searched for the green thallium emission spectrum lines. Instead, they found a bright blue line. Because that blue line did not match any known element, they hypothesized a new element was present in the minerals. They named the element indium, from the [[indigo]] color seen in its spectrum, after the Latin ''indicum'', meaning 'of [[India]]'.<ref>{{cite journal|title = Ueber das Indium|author = Reich, F.|author2 = Richter, T.|journal = Journal für Praktische Chemie|volume = 90|issue = 1|pages = 172–176|date = 1863|doi = 10.1002/prac.18630900122|s2cid s2cid=94381243 94381243|language = de|url = https://zenodo.org/record/1427838|access-date = 2019-06-30|archive-date = 2020-02-02|archive-url = https://web.archive.org/web/20200202154729/https://zenodo.org/record/1427838|url-status = live}}</ref><ref name="Venetskii">{{cite journal|title = Indium|last = Venetskii|first = S.|journal = Metallurgist|volume = 15|issue = 2|pages = 148–150|date = 1971|doi = 10.1007/BF01088126}}</ref><ref name="Greenwood244">Greenwood and Earnshaw, p. 244</ref><ref name="Weeks">{{cite journal|author=Weeks, Mary Elvira |author-link=Mary Elvira Weeks |title=The Discovery of the Elements: XIII. Some Spectroscopic Studies |journal=Journal of Chemical Education |volume=9 |issue=8 |pages=1413–1434 |url=http://search.jce.divched.org/JCEIndex/FMPro?-db=jceindex.fp5&-lay=wwwform&combo=weeks&-find=&-format=detail.html&-skip=27&-max=1&-token.2=27&-token.3=10 |doi=10.1021/ed009p1413 |year=1932 |bibcode=1932JChEd...9.1413W }}{{dead link|date=April 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

Richter went on to isolate the metal in 1864.<ref>{{cite journal|title = Ueber das Indium|author = Reich, F.|author2=Richter, T.|journal = Journal für Praktische Chemie|volume = 92 |issue = 1 |pages = 480–485 |date = 1864|doi = 10.1002/prac.18640920180|language=de}}</ref> An ingot of {{convert|0.5|kg|lb|abbr=on}} was presented at the [[Exposition Universelle (1867)|World Fair]] 1867.<ref name="SchSch">{{cite book|title = Indium: Geology, Mineralogy, and Economics|first = Ulrich|last = Schwarz-Schampera|author2=Herzig, Peter M.|publisher = Springer|date = 2002|isbn = 978-3-540-43135-0|url = https://books.google.com/books?id=k7x_2_KnupMC&pg=PA1}}</ref> <!-- Until 1924, only approximately a gram of indium constituted the world's supply.<ref name=g1>{{cite journal|doi =10.1063/1.1769802|title =New Materials|year =1941|last1 =Olpin|first1 = A. R.|journal =Review of Scientific Instruments|volume =12|pagespage =560|issue =11|bibcode = 1941RScI...12..560O }}</ref><ref name=g2>{{cite book|url=https://books.google.com/books?id=QdU-lRMjOsgC&pg=PA24|title=Infectious diseases and pathology of reptiles: color atlas and text|author=Jacobson, E. R.|page=24|publisher=CRC Press|year=2007|isbn=0-8493-2321-5}}</ref> --> Reich and Richter later fell out when the latter claimed to be the sole discoverer.<ref name="Weeks" />

Indium is the [[Abundance of elements in Earth's crust|68th most abundant element in Earth's crust]] at approximately 50 [[parts per billion|ppb]]. This is similar to the crustal abundance of [[silver]], [[bismuth]] and [[Mercury (element)|mercury]]. It very rarely forms its own minerals, or occurs in elemental form. Fewer than 10 indium minerals such as [[roquesite]] (CuInS₂) are known, and none occur at sufficient concentrations for economic extraction.<ref name=":0Frenzel-2016">{{Cite journal|url=https://www.researchgate.net/publication/309583931|title=The distribution of gallium, germanium and indium in conventional and non-conventional resources - Implications for global availability (PDF Download Available)|website=ResearchGate|doi=10.13140/rg.2.2.20956.18564|access-date=2017-06-02|year=2016|last1=Frenzel|first1=Max|archive-date=2018-10-06|archive-url=https://web.archive.org/web/20181006235214/https://www.researchgate.net/publication/309583931|url-status=live}}</ref> Instead, indium is usually a trace constituent of more common ore minerals, such as [[sphalerite]] and [[chalcopyrite]].<ref>{{Cite journal|last1=Frenzel|first1=Max|last2=Hirsch|first2=Tamino|last3=Gutzmer|first3=Jens|date=July 2016|title=Gallium, germanium, indium, and other trace and minor elements in sphalerite as a function of deposit type — A meta-analysis|journal=Ore Geology Reviews|volume=76|pages=52–78|doi=10.1016/j.oregeorev.2015.12.017|bibcode=2016OGRv...76...52F }}</ref><ref>{{Cite journal|last1=Bachmann|first1=Kai|last2=Frenzel|first2=Max|last3=Krause|first3=Joachim|last4=Gutzmer|first4=Jens|date=June 2017|title=Advanced Identification and Quantification of In-Bearing Minerals by Scanning Electron Microscope-Based Image Analysis|journal=Microscopy and Microanalysis|volume=23|issue=3|pages=527–537|doi=10.1017/S1431927617000460|pmid=28464970|issn=1431-9276|bibcode=2017MiMic..23..527B|s2cid=6751828}}</ref> From these, it can be extracted as a [[by-product]] during smelting.<ref name=":1Frenzel-2017">{{Cite journal|last1=Frenzel|first1=Max|last2=Mikolajczak|first2=Claire|last3=Reuter|first3=Markus A.|last4=Gutzmer|first4=Jens|date=June 2017|title=Quantifying the relative availability of high-tech by-product metals – The cases of gallium, germanium and indium|journal=Resources Policy|volume=52|pages=327–335|doi=10.1016/j.resourpol.2017.04.008|bibcode=2017RePol..52..327F |doi-access=free}}</ref> While the enrichment of indium in these deposits is high relative to its crustal abundance, it is insufficient, at current prices, to support extraction of indium as the main product.<ref name=":0Frenzel-2016" />

Different estimates exist of the amounts of indium contained within the ores of other metals.<ref name="USGSCS2007">{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/indium/indiumcs07.pdf|title=Mineral Commodities Summary 2007: Indium|publisher=United States Geological Survey|access-date=2007-12-26|archive-date=2008-05-09|archive-url=https://web.archive.org/web/20080509184325/http://minerals.usgs.gov/minerals/pubs/commodity/indium/indiumcs07.pdf|url-status=live}}</ref><ref>{{Cite journal|last1=Werner|first1=T. T.|last2=Mudd|first2=G. M.|last3=Jowitt|first3=S. M.|date=2015-10-02|title=Indium: key issues in assessing mineral resources and long-term supply from recycling|journal=Applied Earth Science|volume=124|issue=4|pages=213–226|doi=10.1179/1743275815Y.0000000007|bibcode=2015AdEaS2015ApEaS.124..213W |s2cid=128555024|issn=0371-7453}}</ref> However, these amounts are not extractable without mining of the host materials (see Production and availability). Thus, the availability of indium is fundamentally determined by the ''rate'' at which these ores are extracted, and not their absolute amount. This is an aspect that is often forgotten in the current debate, e.g. by the Graedel group at Yale in their criticality assessments,<ref>{{Cite journal|last1=Graedel|first1=T. E.|last2=Barr|first2=Rachel|last3=Chandler|first3=Chelsea|last4=Chase|first4=Thomas|last5=Choi|first5=Joanne|last6=Christoffersen|first6=Lee|last7=Friedlander|first7=Elizabeth|last8=Henly|first8=Claire|last9=Jun|first9=Christine|date=2012-01-17|title=Methodology of Metal Criticality Determination|journal=Environmental Science & Technology|volume=46|issue=2|pages=1063–1070|doi=10.1021/es203534z|pmid=22191617|issn=0013-936X|bibcode=2012EnST...46.1063G}}</ref> explaining the paradoxically low depletion times some studies cite.<ref>{{Cite journal|last1=Harper|first1=E. M.|last2=Kavlak|first2=Goksin|last3=Burmeister|first3=Lara|last4=Eckelman|first4=Matthew J.|last5=Erbis|first5=Serkan|last6=Sebastian Espinoza|first6=Vicente|last7=Nuss|first7=Philip|last8=Graedel|first8=T. E.|date=2015-08-01|title=Criticality of the Geological Zinc, Tin, and Lead Family|journal=Journal of Industrial Ecology|volume=19|issue=4|pages=628–644|doi=10.1111/jiec.12213|bibcode=2015JInEc..19..628H |s2cid=153380535|issn=1530-9290|url=http://hdl.handle.net/10.1111/jiec.2015.19.issue-4}}{{Dead link|date=October 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name=":1Frenzel-2017" />

Indium is produced exclusively as a [[by-product]] during the processing of the ores of other metals. Its main source material are sulfidic zinc ores, where it is mostly hosted by sphalerite.<ref name=":1Frenzel-2017" /> Minor amounts are probably also extracted from sulfidic copper ores. During the [[Zinc smelting|roast-leach-electrowinning process of zinc smelting]], indium accumulates in the iron-rich residues. From these, it can be extracted in different ways. It may also be recovered directly from the process solutions. Further purification is done by [[electrolysis]].<ref name="Greenwood247">Greenwood and Earnshaw, p. 247</ref> The exact process varies with the mode of operation of the smelter.<ref name="InProcess" /><ref name=":1Frenzel-2017" />

Its by-product status means that indium production is constrained by the amount of sulfidic zinc (and copper) ores extracted each year. Therefore, its availability needs to be discussed in terms of supply potential. The supply potential of a by-product is defined as that amount which is economically extractable from its host materials ''per year'' under current market conditions (i.e. technology and price).<ref>{{Cite journal|last1=Frenzel|first1=Max|last2=Tolosana-Delgado|first2=Raimon|last3=Gutzmer|first3=Jens|date=December 2015|title=Assessing the supply potential of high-tech metals – A general method|journal=Resources Policy|volume=46, Part 2|pages=45–58|doi=10.1016/j.resourpol.2015.08.002|bibcode=2015RePol..46...45F }}</ref> Reserves and resources are not relevant for by-products, since they ''cannot'' be extracted independently from the main-products.<ref name=":1Frenzel-2017" /> Recent estimates put the supply potential of indium at a minimum of 1,300 t/yr from sulfidic zinc ores and 20 t/yr from sulfidic copper ores.<ref name=":1Frenzel-2017" /> These figures are significantly greater than current production (655 t in 2016).<ref name=":2USGS-2017">{{Cite book|url=https://minerals.usgs.gov/minerals/pubs/commodity/indium/mcs-2017-indiu.pdf|title=Indium - in: USGS Mineral Commodity Summaries|publisher=United States Geological Survey|year=2017|access-date=2017-06-02|archive-date=2019-01-11|archive-url=https://web.archive.org/web/20190111092318/https://minerals.usgs.gov/minerals/pubs/commodity/indium/mcs-2017-indiu.pdf|url-status=live}}</ref> Thus, major future increases in the by-product production of indium will be possible without significant increases in production costs or price. The average indium price in 2016 was {{US$}}240/kg, down from {{US$}}705/kg in 2014.<ref>{{Cite web|url=https://minerals.usgs.gov/minerals/pubs/historical-statistics/index.html|title=Historical Statistics for Mineral and Material Commodities in the United States|last1=Kelly|first1=TD|last2=Matos|first2=GR|date=2015|access-date=2017-06-02|archive-date=2017-05-11|archive-url=https://web.archive.org/web/20170511080923/https://minerals.usgs.gov/minerals/pubs/historical-statistics/index.html|url-status=live}}</ref>

China is a leading producer of indium (290 tonnes in 2016), followed by South Korea (195 t), Japan (70 t) and Canada (65 t).<ref name=":2USGS-2017" /> The [[Teck Resources]] refinery in [[Trail, British Columbia]], is a large single-source indium producer, with an output of 32.5&nbsp;tonnes in 2005, 41.8&nbsp;tonnes in 2004 and 36.1&nbsp;tonnes in 2003.

The primary consumption of indium worldwide is [[Liquid crystal display|LCD]] production. Demand rose rapidly from the late 1990s to 2010 with the popularity of LCD computer monitors and television sets, which now account for 50% of indium consumption.<ref name=":0">{{cite web|title = Indium Price Supported by LCD Demand and New Uses for the Metal|work = Geology.com|format = PDF|url = http://geology.com/articles/indium.shtml|access-date = 2007-12-26|archive-url = https://web.archive.org/web/20071221130320/http://geology.com/articles/indium.shtml|archive-date = 2007-12-21|url-status = dead}}</ref> Increased manufacturing efficiency and recycling (especially in Japan) maintain a balance between demand and supply. According to the [[UNEP]], indium's end-of-life recycling rate is less than 1%.<ref name="USGS2011">{{cite web|title=USGS Mineral Commodity Summaries 2011|url=http://minerals.usgs.gov/minerals/pubs/mcs/2011/mcs2011.pdf|publisher=USGS and USDI|access-date=August 2, 2011|archive-date=January 11, 2019|archive-url=https://web.archive.org/web/20190111211631/https://minerals.usgs.gov/minerals/pubs/mcs/2011/mcs2011.pdf|url-status=live}}</ref>

In 1924, indium was found to have a valued property of stabilizing [[non-ferrous metals]], and that became the first significant use for the element.<ref name="dd">{{cite journal |doi = 10.1021/ed011p270 |title = A story of indium |date = 1934 |last1 = French |first1 = Sidney J. |journal = Journal of Chemical Education |volume = 11 |issue = 5 |page = 270|bibcode = 1934JChEd..11..270F }}</ref> The first large-scale application for indium was coating [[bearing (mechanical)|bearings]] in high-performance [[aircraft]] engines during [[World War II]], to protect against damage and [[corrosion]]; this is no longer a major use of the element.<ref name="Greenwood247" /> New uses were found in [[fusible alloy]]s, [[solder]]s, and [[electronics]]. In the 1950s, tiny beads of indium were used for the emitters and collectors of PNP [[alloy-junction transistor]]s. In the middle and late 1980s, the development of [[indium phosphide]] [[semiconductor]]s and [[indium tin oxide]] thin films for [[liquid-crystal display]]s (LCD) aroused much interest. By 1992, the thin-film application had become the largest end use.<ref name="USGSYB2007">{{cite web|title = Mineral Yearbook 2007: Indium|publisher = United States Geological Survey|first = Amy C.|last = Tolcin|url = http://minerals.usgs.gov/mineralofthemonth/indium.pdf|access-date = 2009-12-03|archive-date = 2016-12-31|archive-url = https://web.archive.org/web/20161231013853/https://minerals.usgs.gov/mineralofthemonth/indium.pdf|url-status = live}}</ref><ref name="Downs">{{cite book|title = Chemistry of Aluminium, Gallium, Indium, and Thallium |first =Anthony John|last = Downs|publisher = Springer|date = 1993|isbn = 978-0-7514-0103-5|pages = 89 and 106|url = https://books.google.com/books?id=v-04Kn758yIC}}</ref>

Indium(III) oxide and [[indium tin oxide]] (ITO) are used as a [[transparency (optics)|transparent]] [[electrical conductor|conductive]] coating on [[glass]] substrates in [[electroluminescent]] panels.<ref>{{cite web|title=The Electroluminescent Light Sabre |work=Nanotechnology News Archive |publisher=Azonano |date=June 2, 2005 |url=http://azonano.com/news.asp?newsID=1007 |access-date=2007-08-29 |url-status=dead |archive-url=https://web.archive.org/web/20071012003936/http://azonano.com/news.asp?newsID=1007 |archive-date=October 12, 2007 }}</ref> Indium tin oxide is used as a light filter in [[sodium-vapor lamp#Low-pressure sodium|low-pressure sodium-vapor lamps]]. The [[infrared radiation]] is reflected back into the lamp, which increases the temperature within the tube and improves the performance of the lamp.<ref name="Downs" />

Indium is one of many substitutes for mercury in [[alkaline batteries]] to prevent the [[zinc]] from corroding and releasing [[hydrogen]] gas.<ref>{{cite book|title=Minerals Yearbook, 2008, V. 1, Metals and Minerals|author=Geological Survey (U.S.)|date=2010|pages=35–2|publisher=Government Printing Office|isbn=978-1-4113-3015-3}}</ref> Indium is added to some [[dental amalgam]] alloys to decrease the [[surface tension]] of the mercury and allow for less mercury and easier amalgamation.<ref>{{cite journal|authorsauthor=Powell L. V., |author2=Johnson G. H., |author3=Bales D. J. |title=Effect of Admixed Indium on Mercury Vapor Release from Dental Amalgam|journal=Journal of Dental Research|volume=68|issue=8|pages=1231–3|doi=10.1177/00220345890680080301|pmid=2632609|year=1989|citeseerx=10.1.1.576.2654|s2cid=28342583}}</ref>

Indium's high neutron-capture cross-section for thermal neutrons makes it suitable for use in [[control rod]]s for [[nuclear reactors]], typically in an alloy of 80% [[silver]], 15% indium, and 5% [[cadmium]].<ref>{{cite book | chapter-url = https://books.google.com/books?id=9yzN-QGag_8C&pg=PA222 | page = 222 | chapter= Other types of cadmium alloys | title = Mercury, cadmium, lead: handbook for sustainable heavy metals policy and regulation | isbn = 978-1-4020-0224-3 | author1 = Scoullos, Michael J. | date = 2001-12-31| publisher = Springer }}</ref> In nuclear engineering, the (n,n') reactions of ¹¹³In and ¹¹⁵In are used to determine magnitudes of neutron fluxes.<ref>{{cite book | chapter-url = https://books.google.com/books?id=b1ZwQXdxAtUC&pg=PA50 | pages = 50–51 | chapter = Image Detectors for Other Neutron Energies | title = Practical applications of neutron radiography and gaging: a symposium | author1 = Berger, Harold | author2 = National Bureau Of Standards, United States | author3 = Committee E-7 On Nondestructive Testing, American Society for Testing and Materials | date = 1976}}</ref>

In 2009, Professor [[Mas Subramanian]] and associatesformer graduate student Andrew Smith at [[Oregon State University]] discovered that indium can be combined with [[yttrium]] and [[manganese]] to form an intensely [[blue]], non-toxic, inert, fade-resistant [[pigment]], [[YInMn blue]], the first new inorganic blue pigment discovered in 200 years.<ref name="Kupferschmidt pp. 424–429">{{cite journal | last=Kupferschmidt | first=Kai | title=In search of blue | journal=Science | publisher=American Association for the Advancement of Science (AAAS) | volume=364 | issue=6439 | date=2019-05-02 | issn=0036-8075 | doi=10.1126/science.364.6439.424 | pages=424–429| pmid=31048474 | bibcode=2019Sci...364..424K | s2cid=143434096 }}</ref>

| PPhrases = {{P-phrases|261|280|305+351+338}}<ref>{{cite web | url=https://www.sigmaaldrich.com/catalog/product/aldrich/57083?lang=en&region=US | title=Indium 57083 | access-date=2018-10-02 | archive-date=2018-10-02 | archive-url=https://web.archive.org/web/20181002172504/https://www.sigmaaldrich.com/catalog/product/aldrich/57083?lang=en&region=US | url-status=live }}</ref>

}}</ref> though hydrated indium oxide is more than forty times as toxic when injected, measured by the quantity of indium introduced.<ref name="toxic" /> Radioactive indium-111 (in very small amounts on a chemical basis) is used in [[nuclear medicine]] tests, as a [[radiotracer]] to follow the movement of labeled proteins and [[indium leukocyte imaging|white blood cells]] in the body.<ref name="Indium-111 Radiochemical Indium Chloride Solution">{{cite web|title=IN-111 FACT SHEET|url=http://www.nordion.com/documents/products/In-111_Can.pdf|publisher=Nordion(Canada), Inc.|access-date=23 September 2012|url-status=dead|archive-url=https://web.archive.org/web/20111203082605/http://www.nordion.com/documents/products/In-111_Can.pdf|archive-date=3 December 2011}}</ref><ref>{{cite journal |last1=Van Nostrand |first1=D. |last2=Abreu |first2=S. H. |last3=Callaghan |first3=J. J. |last4=Atkins |first4=F. B. |last5=Stoops |first5=H. C. |last6=Savory |first6=C. G. |date=May 1988 |title=In-111-labeled white blood cell uptake in noninfected closed fracture in humans: prospective study |journal=Radiology |volume=167 |issue= 2|pages=495–498 |pmid=3357961 | doi = 10.1148/radiology.167.2.3357961}}</ref> Indium compounds are mostly not absorbed upon ingestion and are only moderately absorbed on inhalation; they tend to be stored temporarily in the [[muscle]]s, [[skin]], and [[bone]]s before being excreted, and the [[biological half-life]] of indium is about two weeks in humans.<ref>{{cite book |first1=Gunnar F. |last1=Nordberg |first2=Bruce A. |last2=Fowler |first3=Monica |last3=Nordberg |title=Handbook on the Toxicology of Metals |publisher=Academic Press |page=845 |edition=4th |date=7 August 2014 |isbn=978-0-12-397339-9}}</ref>

People can be exposed to indium in the workplace by inhalation, ingestion, skin contact, and eye contact. [[Indium lung]] is a lung disease characterized by pulmonary alveolar proteinosis and pulmonary fibrosis, first described by Japanese researchers in 2003. {{As of|2010}}, 10 cases had been described, though more than 100 indium workers had documented respiratory abnormalities.<ref name="Sauler">{{cite journal|last1=Sauler|first1=Maor|last2=Gulati|first2=Mridu|title=Newly Recognized Occupational and Environmental Causes of Chronic Terminal Airways and Parenchymal Lung Disease|journal=Clinics in Chest Medicine|date=December 2012|volume=33|issue=4|pages=667–680|doi=10.1016/j.ccm.2012.09.002|pmid=23153608|pmc=3515663}}</ref> The [[National Institute for Occupational Safety and Health]] has set a [[recommended exposure limit]] (REL) of 0.1&nbsp;mg/m³ over an eight-hour workday.<ref>{{Cite web|title = CDC – NIOSH Pocket Guide to Chemical Hazards – Indium|url = https://www.cdc.gov/niosh/npg/npgd0341.html|website = www.cdc.gov|access-date = 2015-11-06|archive-date = 2015-12-08|archive-url = https://web.archive.org/web/20151208163910/http://www.cdc.gov/niosh/npg/npgd0341.html|url-status = live}}</ref>

* [http://www.periodicvideos.com/videos/049.htm Indium] {{Webarchive|url=https://web.archive.org/web/20230313152040/http://www.periodicvideos.com/videos/049.htm |date=2023-03-13 }} at ''[[The Periodic Table of Videos]]'' (University of Nottingham)

* [https://www.organic-chemistry.org/chemicals/reductions/indiumlowvalent.shtm Reducing Agents > Indium low valent] {{Webarchive|url=https://web.archive.org/web/20230709174439/https://www.organic-chemistry.org/chemicals/reductions/indiumlowvalent.shtm |date=2023-07-09 }}

* [https://www.cdc.gov/niosh/npg/npgd0341.html NIOSH Pocket Guide to Chemical Hazards] {{Webarchive|url=https://web.archive.org/web/20151208163910/http://www.cdc.gov/niosh/npg/npgd0341.html |date=2015-12-08 }} (Centers for Disease Control and Prevention)