Indium(III) oxide

Amorphous indium oxide is insoluble in water but soluble in acids, whereas crystalline indium oxide is insoluble in both water and acids. The crystalline form exists in two phases, the cubic (bixbyite type) and rhombohedral (corundum type). Both phases have a band gap of about 3 eV.{{cite journal|author=Walsh, A|title=Nature of the Band Gap of In₂O₃ Revealed by First-Principles Calculations and X-Ray Spectroscopy|pmid=18518246|display-authors=1|year=2008|last2=Da Silva|first2=JL|last3=Wei|first3=SH|last4=Körber|first4=C|last5=Klein|first5=A|last6=Piper|first6=LF|last7=Demasi|first7=A|last8=Smith|first8=KE|last9=Panaccione|first9=G|volume=100|issue=16|pages=167402|journal=Physical Review Letters|doi=10.1103/PhysRevLett.100.167402|bibcode=2008PhRvL.100p7402W |url=http://people.bath.ac.uk/aw558/publications/2008/prl_in2o3_08.pdf|access-date=2016-11-25|archive-date=2017-12-15|archive-url=https://web.archive.org/web/20171215094231/http://people.bath.ac.uk/aw558/publications/2008/prl_in2o3_08.pdf|url-status=dead}}{{cite journal|last1=King|title=Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In₂O₃|doi=10.1103/PhysRevB.79.205211 |first1=P. D. C. |display-authors=2 |year=2009 |last2=Fuchs |first2=F. |last3=Wang |first3=Ch. |last4=Payne |first4=D. |last5=Bourlange |first5=A. |last6=Zhang |first6=H. |last7=Bell |first7=G. |last8=Cimalla |first8=V. |last9=Ambacher |first9=O. |last10=Egdell |first10=R. |last11=Bechstedt |first11=F. |last12=McConville |first12=C. |journal=Physical Review B|volume=79|issue=20|page=205211 |bibcode=2009PhRvB..79t5211K |s2cid=53118924|url=http://pdfs.semanticscholar.org/0343/3764b328ac71dea8f32f6c06f717bae2f9e0.pdf|archive-url=https://web.archive.org/web/20191231012553/http://pdfs.semanticscholar.org/0343/3764b328ac71dea8f32f6c06f717bae2f9e0.pdf|url-status=dead|archive-date=2019-12-31}} The parameters of the cubic phase are listed in the infobox.

The rhombohedral phase is produced at high temperatures and pressures or when using non-equilibrium growth methods.{{cite book|author1=The Minerals Metals & Materials Society (Tms)|author2=The Minerals, Metals & Materials Society (TMS)|title=TMS 2011 140th Annual Meeting and Exhibition, General Paper Selections|url=https://books.google.com/books?id=2WKwuVASXjEC&pg=PA51|access-date=23 September 2011|date=6 April 2011|publisher=John Wiley and Sons|isbn=978-1-118-06215-9|pages=51–}} It has a space group R{{overline|3}}c No. 167, Pearson symbol hR30, a = 0.5487 nm, b = 0.5487 nm, c = 1.4510 nm, Z = 6 and calculated density 7.31 g/cm³.{{cite journal|doi=10.1021/ic50079a033|title=C rare earth oxide-corundum transition and crystal chemistry of oxides having the corundum structure|year=1969|last1=Prewitt|first1=Charles T.|last2=Shannon|first2=Robert D.|last3=Rogers|first3=Donald Burl|last4=Sleight|first4=Arthur W.|journal=Inorganic Chemistry|volume=8|issue=9|pages=1985–1993}}

Thin films of chromium-doped indium oxide (In_2−xCr_xO₃) are a magnetic semiconductor displaying high-temperature ferromagnetism, single-phase crystal structure, and semiconductor behavior with high concentration of charge carriers. It has possible applications in spintronics as a material for spin injectors.{{cite journal|doi=10.2345/i0899-8205-40-4-267.1|url=https://news.mit.edu/2006/spintronics-0524|title=New Material Puts Its Own Spin on Electronics|journal=Biomedical Instrumentation & Technology|volume=40|issue=4|pages=267|year=2006}}

Thin polycrystalline films of indium oxide doped with Zn²⁺ are highly conductive (conductivity ~10⁵ S/m) and even superconductive at liquid helium temperatures. The superconducting transition temperature T_c depends on the doping and film structure and is below 3.3 K.{{cite journal|doi=10.1088/1468-6996/9/4/044208 |pmid=27878025|title=Superconductivity in transparent zinc-doped In₂O₃ films having low carrier density|year=2008|last1=Makise|first1=Kazumasa|last2=Kokubo|first2=Nobuhito|last3=Takada|first3=Satoshi|last4=Yamaguti|first4=Takashi|last5=Ogura|first5=Syunsuke|last6=Yamada|first6=Kazumasa|last7=Shinozaki|first7=Bunjyu|last8=Yano|first8=Koki|last9=Inoue|first9=Kazuyoshi|last10=Nakamura|first10=Hiroaki|journal=Science and Technology of Advanced Materials|volume=9|issue=4|pages=044208|display-authors=8|pmc=5099639|bibcode=2008STAdM...9d4208M }}

Bulk samples can be prepared by heating indium(III) hydroxide or the nitrate, carbonate or sulfate.{{Cite book| title = Chemistry of aluminium, gallium, indium, and thallium| author = Downs, Anthony John | publisher = Springer| year = 1993| isbn = 0-7514-0103-X}}

Thin films of indium oxide can be prepared by sputtering of indium targets in an argon/oxygen atmosphere. They can be used as diffusion barriers ("barrier metals") in semiconductors, e.g. to inhibit diffusion between aluminium and silicon.{{cite journal|title = Indium oxide diffusion barriers for Al/Si metallizations|author = Kolawa, E. and Garland, C. and Tran, L. and Nieh, C. W. and Molarius, J. M. and Flick, W. and Nicolet, M.-A. and Wei, J.|year = 1988|journal = Applied Physics Letters|volume = 53|issue = 26|pages = 2644–2646|doi = 10.1063/1.100541|bibcode = 1988ApPhL..53.2644K|doi-access = free}}

Monocrystalline nanowires can be synthesized from indium oxide by laser ablation, allowing precise diameter control down to 10 nm. Field effect transistors were fabricated from those.{{cite journal|doi=10.1196/annals.1292.007|title=Synthesis, Electronic Properties, and Applications of Indium Oxide Nanowires|year=2003|last1=Li|first1=C|last2=Zhang|first2=D|last3=Han|first3=S|last4=Liu|first4=X|last5=Tang|first5=T|last6=Lei|first6=B|last7=Liu|first7=Z|last8=Zhou|first8=C|journal=Annals of the New York Academy of Sciences|volume=1006|issue=1 |pages=104–21|pmid=14976013|bibcode=2003NYASA1006..104L |s2cid=5176429}} Indium oxide nanowires can serve as sensitive and specific redox protein sensors.{{cite web|url = http://www.foresight.org/Conferences/MNT11/Abstracts/Rouhanizadeh/index.html|title = Applying Indium Oxide Nanowires as Sensitive and Specific Redox Protein Sensors|publisher = Foresight Nanotech Institute|access-date = 2008-10-29|archive-date = 2008-08-08|archive-url = https://web.archive.org/web/20080808115137/http://www.foresight.org/Conferences/MNT11/Abstracts/Rouhanizadeh/index.html|url-status = dead}} The sol–gel method is another way to prepare nanowires.{{Citation needed|date=March 2021}}

Indium oxide can serve as a semiconductor material, forming heterojunctions with p-InP, n-GaAs, n-Si, and other materials. A layer of indium oxide on a silicon substrate can be deposited from an indium trichloride solution, a method useful for manufacture of solar cells.Feng, Tom and Ghosh, Amal K. (1984) "Method for forming indium oxide/n-silicon heterojunction solar cells" {{US Patent| 4436765}}

When heated to 700 °C, indium(III) oxide forms In₂O, (called indium(I) oxide or indium suboxide), at 2000 °C it decomposes.

It is soluble in acids but not in alkali.

With ammonia at high temperature indium nitride is formed:Wiberg, Egon and Holleman, Arnold Frederick (2001) Inorganic Chemistry, Elsevier {{ISBN|0123526515}}

: In₂O₃ + 2 NH₃ → 2 InN + 3 H₂O

With K₂O and indium metal the compound K₅InO₄ containing tetrahedral InO₄⁵⁻ ions was prepared.{{cite journal|last1=Lulei|first1=M.|last2=Hoppe|first2=R.|title=Über "Orthoindate" der Alkalimetalle: Zur Kenntnis von K₅[InO₄]|journal=Zeitschrift für anorganische und allgemeine Chemie|volume=620|issue=2|year=1994|pages=210–224|doi=10.1002/zaac.19946200205}}

Reacting with a range of metal trioxides produces perovskites{{cite journal|last1=Shannon|first1=Robert D.|title=Synthesis of some new perovskites containing indium and thallium|journal=Inorganic Chemistry|volume=6|issue=8|year=1967|pages=1474–1478|issn=0020-1669|doi=10.1021/ic50054a009}} for example:

:In₂O₃ + Cr₂O₃ → 2InCrO₃

Indium oxide is used in some types of batteries, thin film infrared reflectors transparent for visible light (hot mirrors), some optical coatings, and some antistatic coatings. In combination with tin dioxide, indium oxide forms indium tin oxide (also called tin doped indium oxide or ITO), a material used for transparent conductive coatings.

In semiconductors, indium oxide can be used as an n-type semiconductor used as a resistive element in integrated circuits.{{cite web|url=http://www.ceramic-materials.com/cermat/oxide/in2o3.html|title = In₂O₃ (Indium Oxide)|publisher = CeramicMaterials.info|access-date = 2008-10-29 |archive-url = https://web.archive.org/web/20080630082830/http://ceramic-materials.com/cermat/oxide/in2o3.html |archive-date = 2008-06-30}}

In histology, indium oxide is used as a part of some stain formulations.

• Indium
• Indium tin oxide
• Magnetic semiconductor

{{Reflist|30em}}

{{Indium compounds}}

{{Oxides}}

{{oxygen compounds}}

Category:Indium compounds

Category:Semiconductor materials

Category:Sesquioxides