Chemistry:Indium(III) sulfate

From HandWiki
Indium(III) sulfate
Other names
Indium sulfate
3D model (JSmol)
EC Number
  • 236-689-1
RTECS number
  • NL1925000
Molar mass 517.81 g/mol
Appearance white-gray odorless powder, hygroscopic, monoclinic crystals
Density 3.44 g/cm3, solid
Melting point decomposes at 600 °C[1]
soluble, (539.2 g/L at 20 °C)[2]
monoclinic (room temperature)
a = 8.57 Å[3], b = 8.908 Å, c = 14.66 Å
α = 90°, β = 124.72°, γ = 90°
a = 8.44 Å[3][4], b = 8.44 Å, c = 23.093 Å
α = 90°, β = 90°, γ = 120°
6 formula per cell
Safety data sheet tttmetalpowder
GHS pictograms GHS07: Harmful
GHS Signal word Warning
H315, H319, H335
P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P403+233, P405, P501
NFPA 704 (fire diamond)
0.1[6] (TWA), 0.3[6] (STEL)
NIOSH (US health exposure limits):
PEL (Permissible)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☑Y verify (what is ☑Y☒N ?)
Infobox references

Indium(III) sulfate (In2(SO4)3) is a sulfate salt of the metal indium. It is a sesquisulfate, meaning that the sulfate group occurs 11/2 times as much as the metal. It may be formed by the reaction of indium, its oxide, or its carbonate with sulfuric acid. An excess of strong acid is required, otherwise insoluble basic salts are formed.[8] As a solid indium sulfate can be anhydrous, or take the form of a pentahydrate with five water molecules[9] or a nonahydrate with nine molecules of water. Indium sulfate is used in the production of indium or indium containing substances. Indium sulfate also can be found in basic salts, acidic salts or double salts including indium alum.


In water solution, the indium ion forms a complex with water and sulfate, examples being In(H2O)5(SO4)+ and In(H2O)4(SO4)2.[10][11] Indium is unusual in forming a sulfate complex. The effect on the sulfate ion is revealed in the Raman spectrum.[8] The proportion of sulfate complex increases with temperature showing the reaction that forms it is endothermic. The proportion also increases with concentration of the solution and can be over a half.[12] The sulfate complex rapidly exchanges with water at a rate of over 10,000,000 per second, so that NMR cannot detect the difference that results from a complexed and noncomplexed indium ion.[12] An indium sulfate water solution is quite acidic with a 0.14 mol/liter solution having a pH of 1.85. If the pH rises above 3.4 then a precipitate will form.[13]

The Raman spectrum of the solution shows lines at 650, 1000 and 1125 cm−1 due to a sulfur–oxygen bonds in sulfate bound to indium. A line at 255 cm−1 is due to the indium-oxygen bond to the sulfate. The water attached to the indium atom causes a band at about 400 cm−1.[8]

Solid anhydrous indium sulfate has two crystalline forms. When formed by chlorine gas chemical transport at 848 K, it has a monoclinic form with unit cell dimensions a = 8.570 Å, b = 8.908 Å and c = 12.0521 Å, β = 91.05°, and four formulae per cell. A high temperature form deposited at 973K has a hexagonal (or rhombohedral) form with cell dimensions of a = 8.440 Å, c = 23.093 Å and six formulae per cell.[14]

During extraction of indium, a sulfate solution of mixed metals, including indium sulfate, has trivalent metals partitioned into a kerosene solution of di-2-ethylhexyl hydrogen phosphate. Isododecylphosphetanic and diisooctylphosphinic acids can also be used for this function. The kerosene mixture is then backwashed with an acid to recover the metals in a water solution and regenerate the extracting fluid.[15]


Indium metal reacts with cold concentrated sulfuric acid to produce Indium sulfate and hydrogen gas. If hot concentrated sulfuric acid is used indium will reduce the sulfuric acid to sulfur dioxide.[16]

Indium sulfate can also be produced from a reaction of sulfuric acid on indium oxide, indium carbonate, or indium hydroxide.


When heated to 710 K (437 °C) or above, indium sulfate decomposes by giving off sulfur trioxide vapour, yielding indium oxide.[17]

[math]\ce{ In2(SO4)3 -> In2O3 + 3SO3 }[/math]

Alkalis added to indium sulfate solutions precipitate basic salts. For example, potassium hydroxide produces either a basic sulfate, 2In2O3.SO3·nH2O, or KIn3(OH)6(SO4)2 depending on pH.[18] Sodium pyrophosphate causes a slimy precipitate of indium pyrophosphate, In4(P2O7)3·3H2O. Potassium periodate causes a precipitate of a basic indium periodate, 2InO5·In(OH)3·6H2O .[19] Oxalic acid causes a precipitate of indium oxalate, In2(C2O4)3·10H2O. Alkali oxalates cause a precipitate of the alkali dioxalatoindate to form MIn(C2O4)2·3H2O, where M = Na, K or NH4.[20]

Related compounds

Hydrogen sulfates

An acid sulfate, indium hydrogensulfate tetrahydrate with the formula HIn(SO4)2·4H2O crystallises in the orthorhombic system with unit cell dimensions a = 9.997 Å, b = 5.477 Å, c = 18.44 Å, with four of the formula per cell. The density is 2.50 cm−3. In the acid sulfate, two water molecules are linked to the indium atom and a hydronium ion H5O2 takes care of the proton. This is part of an acid sulfate family that includes Al, Ga, In, Tl(III), Fe(III) and Ti(III). HIn(SO4)2 is made by evaporating an indium sulfate in 40% sulfuric acid solution[21] or cooling indium sulfate in a 60% sulfuric acid solution.[22] As the acid tetrahydrate is heated it gives off water yielding a trihydrate, monohydrate, and an anhydrous form at 370, 385 and 482K. Above 505K it gives out more water and sulfur dioxide yielding the neutral indium sulfate.[22] Indium hydrogensulfate is a proton conductor with conductivity 0.0002Ω−1cm−1.[22]

Basic sulfates

A basic indium sulfate is made by adding ethanol to a water solution of indium sulfate. Crystals can be formed by using a 0.05 molar solution with twice the volume of ethanol, and waiting for several weeks for crystals to form.[23] InOHSO4·(H2O)2 has monoclinic crystals with a=6.06 Å b=7.89 Å c=12.66 Å and β=107.5°. Cell volume is 577.6 Å3.[23] Another basic indium sulfate InOHSO4 with rhombohedral crystals is made by heating an indium sulfate solution at 160 °C or over for about a week in a sealed tube.[24] This insoluble basic salt also forms if indium sulfate solution is diluted below 0.005 molar. So a precipitate forms from diluted solutions as well as from heated solutions.[12]

Anhydrous double sulfates

Two different types of anhydrous double indium sulfates have been made. One is from the family MI3MIII(XO4)3, with MI being a large singly positive ion such as K, Rb, Cs, Tl or NH3; MIII is triply charged and can be Al, Ga, In, Tl, V, Cr, Fe, Sc and other rare earths; and X is S or Se.[25] Most of these have a rhombohedral crystal structure. However, triammonium indium trisulfate, (NH4)3In(SO4)3 converts from rhombohedral to monoclinic as the temperature drops below 80 °C, and converts back into a rhombohedral form with space group R3c as the temperature rises above 110 °C.[25] The low temperature monoclinic form has space group P21/c, a=8.96, b=15.64 c=9.13 β=108.28° Z=4[25] The high temperature form is termed "β-". An explanation for this transition is that ammonium (and also thallium) is a non-spherical ion and thus has lower symmetry. However, when it is heated enough, dynamical disorder causing random orientations makes the ions on average spherically symmetric. Alkali metal ions are spherical in shape at all temperatures and form rhombohedral structures.[25] Double sulfates of this form exist of indium with the alkali metals sodium, potassium, rubidium, and cesium. These can be formed by heating a solid mixture of the individual sulfates to 350 °C.[9]

name formula molecular weight a Å c Å α volume Å3 density
trisodium indium trisulfate [math]\ce{ Na3In(SO4)3 }[/math] 471.97 13.970 8.771 109°00′ 494 3.172
tripotassium indium trisulfate [math]\ce{ K3In(SO4)3 }[/math] 520.30 14.862 8.960 109°45′ 571 3.026
trirubidium indium trisulfate [math]\ce{ Rb3In(SO4)3 }[/math] 659.41 15.413 9.136 110°03′ 626 3.498
tricesium indium trisulfate [math]\ce{ Cs3In(SO4)3 }[/math] 801.72 16.068 9.211 110°36′ 687 3.876
triammonium indium trisulfate [math]\ce{ (NH4)3In(SO4)3 }[/math] 361.06 15.531 9.163 120° 1914.1 1.88
ammonium indium disulfate [math]\ce{ NH4In(SO4)2 }[/math] 324.98 4.902 8.703 73.643 171.27 3.15
rubidium indium disulfate [math]\ce{ RbIn(SO4)2 }[/math] 392.41 4.908 8.7862 73.781 173.50 3.75
cesium indium disulfate [math]\ce{ CsIn(SO4)2 }[/math] 439.85 4.956 9.2567 74.473 187.26 3.90
thallium indium disulfate [math]\ce{ TlIn(SO4)2 }[/math] 511.33 4.919 8.7882 73.748 174.27 4.87

Another series of anhydrous rhombohedral double salts in the same series of TlFe(SO4)2 exists. These can be made by heating a mixture of anhydrous sulfates at 350 °C, or by dehydrating hydrous double alum type salts at 300 °C. The substances in this series are RbIn(SO4)2, CsIn(SO4)2, TlIn(SO4)2 and NH4In(SO4)2. Although KIn(SO4)2 exists it has a different crystalline form.[26]

Hydrated double sulfates

Hydrated double salts of indium in an alum structure exist with formula MIIn(SO4)2·12H2O. All alums have a cubic crystal structure with space group Pa3.[27] The indium cesium alum CsIn(SO4)2•12H2O[12] has formula weight 656.0, unit cell width 12.54 Å, cell volume 1972 Å3 and density 2.20 g/cm3.[27] It has the β alum structure.[28] The cesium alum can be used in the analysis of indium. It precipitates when cesium nitrate is added to indium sulfate solution with extra sulfuric acid added.[29]

Indium ammonium alum NH4In(SO4)2·12H2O[30] is fairly unstable at room temperature and must be crystallised below 5 °C.[31] It decomposes at 36 °C to a tetrahydrate.[32] It changes to a ferroelectric phase below 127K.[33] The alum methyl ammonium indium sulfate dodecahydrate CH3NH3In(SO4)2·12H2O becomes ferroelectric below 164K.[34] Potassium indium alum has not been crystallised.[35] Rubidum indium alum is highly efflorescent very easily losing its water.[36]

Another series of monoclinic hydrated double salts have four water molecules MIn(SO4)2·4H2O, with five formulae per unit cell, where M is NH4, K or Rb and the point group is P21/c. The prototype substance for the series is (NH4)Sm(SO4)2(H2O)4.

formula weight a Å b Å c Å β volume Å3 density ref
NH4In(SO4)2•4H2O 397.04 10.651 10.745 9.279 102.67° 1036.08 3.182 [37]
KIn(SO4)2•4H2O 418.10 10.581 10.641 9.224 101.93° 1016.1 3.416 [38]
RbIn(SO4)2•4H2O 464.47 10.651 10.745 9.279 102.67° 1036.1 3.722 [39]

Cadmium can also form a double sulfate, Cd3In2(SO4)6·26H2O.[40]

Crystals with less water also exist like KIn(SO4)2·H2O.[41]

Organic double sulfates

Organic base double sulfates of indium include the guanidinium salt [C(NH2)3][In(H2O)2(SO4)2], which crystallises in a monoclinic system with space group P21/c a = 4.769 Å, b = 20.416 Å, c = 10.445 Å, β = 93.39°, cell volume 1015.3 Å3, 4 formulas per cell and density 2.637. [H2(4,4'-bi-py)][In2(H2O)6(SO4)4]·2H2O crystallises in the triclinic system with a = 7.143 Å, b = 7.798 Å, c = 12.580 Å, α = 107.61°, β = 98.79°, γ = 93.89°, cell volume 655.2 Å3, one formula per cell and density 2.322.[42] [H(2,2'-bipy)][In(H2O)(SO4)2]·2H2O, the hexamethylenediamine salt [H3N(CH2)6NH3][In(H2O)2(SO4)2]2·2H2O and [H2(Py(CH2)3Py)][In(H2O)2(SO4)2]2·2H2O also exist.[42] Yet other organic derivatives include those of triethylenetetramine,[43] and amylammonium.[30] Tri-μ-sulfato-κ6O:O'-bis[aqua(1,10-phenanthroline-κ2N,N')indium(III)] dihydrate, [In2(SO4)3(C12H8N2)2(H2O)2]·2H2O, has a 1,10-phenanthroline molecule linked to each indium ion. Two indium ions are linked via three sulfate groups. It forms triclinic crystals with two formulas per unit cell. The density is 2.097 g/cm3.[44]

Dimethylindium sulfate [(CH3)2In]2SO4 can be made by reacting trimethylindium with dry sulfuric acid.[45]


A double indium sulfate chloride salt has formula In2(SO4)3·InCl3·(17±1)H2O.[46]


Indium(I) sulfate, In2SO4 can be made in a solid state by heating indium metal with indium(III) sulfate,[47] but when dissolving in water or sulfuric acid, In+ reacts to produce hydrogen gas.[48] The mixed valence salt InIInIII(SO4)2 is also made by heating indium metal with indium(III) sulfate.[49]


Philco surface-barrier transistor developed and produced in 1953

Indium sulfate is a commercially available chemical. It can be used to electroplate indium metal,[50] as a hardening agent in gold electroplating[51] or to prepare other indium containing substances such as copper indium selenide. It has been sold as a health supplement, even though there is no evidence of benefit to humans, and it is toxic.[52]

The first high-frequency transistor was the surface-barrier germanium transistor developed by Philco in 1953, capable of operating up to 60 MHz.[53] These were made by etching depressions into an N-type germanium base from both sides with jets of indium sulfate until it was a few ten-thousandths of an inch thick. Indium electroplated into the depressions formed the collector and emitter.[54][55]


  1. Perry D, Phillips S (1995) Handbook of Inorganic Compounds: Version 2.0, An Electronic Database, CRC Press ISBN:0-8493-8671-3
  2. Indium Sulfate. Product Data Sheet Indium Cooperation
  3. 3.0 3.1 Villars, Pierre; Cenzual, Karin; Gladyshevskii, Roman (2015). Handbook of Inorganic Substances 2015. Walter de Gruyter. p. 654. ISBN 9783110311747. 
  4. Pallister, Peter J.; Moudrakovski, Igor L.; Enright, Gary D.; Ripmeester, John A. (2013). "Structural assessment of anhydrous sulfates with high field 33S solid state NMR and first principles calculations". CrystEngComm 15 (43): 8808. doi:10.1039/C3CE41233D. 
  5. Nilson, L. F.; Pettersson, Otto (1 January 1880). "On the Molecular Heat and Volume of the Rare Earths and Their Sulphates". Proceedings of the Royal Society of London 31 (206–211): 46–51. doi:10.1098/rspl.1880.0005. Bibcode1880RSPS...31...46N. 
  6. 6.0 6.1 6.2 "MSDS OF Indium Sulfate". 
  7. "Sfety Data Sheet Indium sulfate anhydrous 99.99%". Pfaltz & Bauer, Inc.. 
  8. 8.0 8.1 8.2 Hester, Ronald E.; Plane, Robert A.; Walrafen, George E. (1963). "Raman Spectra of Aqueous Solutions of Indium Sulfate, Nitrate, and Perchlorate". The Journal of Chemical Physics 38 (1): 249. doi:10.1063/1.1733470. Bibcode1963JChPh..38..249H. 
  9. 9.0 9.1 Perret, R; Tudo, J; Jolibois, B; Couchot, P (July 1974). "Préparation et caractérisation cristallographique de quelques sulfates doubles d'indium(III) et de thallium(III), MI3MIII (SO4)3 (MI = Na, K, Rb et Cs)" (in fr). Journal of the Less Common Metals 37 (1): 9–12. doi:10.1016/0022-5088(74)90003-4. 
  10. Caminiti, R.; Paschina, G. (September 1981). "An X-ray diffraction study of the structure of the aqua indium(III) ion in indium sulphate solution". Chemical Physics Letters 82 (3): 487–491. doi:10.1016/0009-2614(81)85425-5. Bibcode1981CPL....82..487C. 
  11. Cotton, F. Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry. John Wiley & Sons. p. 438. 
  12. 12.0 12.1 12.2 12.3 Rudolph, Wolfram W.; Fischer, Dieter; Tomney, Madelaine R.; Pye, Cory C. (2004). "Indium(iii) hydration in aqueous solutions of perchlorate, nitrate and sulfate. Raman and infrared spectroscopic studies and ab-initio molecular orbital calculations of indium(iii)-water clusters". Physical Chemistry Chemical Physics 6 (22): 5145. doi:10.1039/b407419j. Bibcode2004PCCP....6.5145R. Retrieved 31 May 2015. 
  13. Busev, A.I. (22 October 2013). The Analytical Chemistry of Indium. Elsevier. p. 30. ISBN 9781483149554. 
  14. Krause, M.; Gruehn, R. (January 1995). "Contributions on the thermal behaviour of sulphates XVII. Single crystal structure refinements of In2(SO4)3 and Ga2(SO4)3". Zeitschrift für Kristallographie 210 (6): 427–431. doi:10.1524/zkri.1995.210.6.427. Bibcode1995ZK....210..427K. 
  15. Travkin, V. F.; Kubasov, V. L.; Glubokov, Yu. M.; Busygina, N. S.; Kazanbaev, L. A.; Kozlov, P. A. (October 2004). "Extraction of indium(III) from sulfate solutions with organophosphorus acids". Russian Journal of Applied Chemistry 77 (10): 1613–1617. doi:10.1007/s11167-005-0082-9. 
  16. Geckler, Robert P.; Marchi, Louis E. (August 1944). "Indium". Journal of Chemical Education 21 (8): 407. doi:10.1021/ed021p407. Bibcode1944JChEd..21..407G. 
  17. Zhou, Huijuan; Cai, Weiping; Zhang, Lide (April 1999). "Synthesis and structure of indium oxide nanoparticles dispersed within pores of mesoporous silica". Materials Research Bulletin 34 (6): 845–849. doi:10.1016/S0025-5408(99)00080-X. 
  18. Grimes, S. M. (1984). "Chapter 4. Al, Ga, In, Tl". Annual Reports on the Progress of Chemistry, Section A 81: 90. doi:10.1039/IC9848100075. 
  19. Busev, A.I. (22 October 2013). The Analytical Chemistry of Indium. Elsevier. pp. 67–68. ISBN 9781483149554. 
  20. Busev, A.I. (22 October 2013). The Analytical Chemistry of Indium. Elsevier. pp. 111–112. ISBN 9781483149554. 
  21. Tudo, J.; Jolibois, B.; Laplace, G.; Nowogrocki, G.; Abraham, F. (15 July 1979). "Structure cristalline du sulfate acide d'indium(III) hydraté" (in fr). Acta Crystallographica Section B 35 (7): 1580–1583. doi:10.1107/s0567740879007172. 
  22. 22.0 22.1 22.2 Voropaeva, E. Yu.; Stenina, I. A.; Yaroslavtsev, A. B. (January 2007). "Proton conduction in indium hydrogensulfate and hydrous zirconia composites". Russian Journal of Inorganic Chemistry 52 (1): 1–6. doi:10.1134/S0036023607010019. 
  23. 23.0 23.1 Johansson, Georg (1961). "The Crystal Structure of [math]\displaystyle{ \scriptstyle\ce{InOHSO4(H2O)2} }[/math]". Acta Chemica Scandinavica 15 (7): 1437–1453. doi:10.3891/acta.chem.scand.15-1437. Retrieved 31 May 2015. 
  24. Johansson, Georg (1962). "The Crystal Structure of FeOHSO4 and InOHSO4". Acta Chemica Scandinavica 16 (5): 1234–1244. doi:10.3891/acta.chem.scand.16-1234. Retrieved 31 May 2015. 
  25. 25.0 25.1 25.2 25.3 Jolibois, B.; Laplace, G.; Abraham, F.; Nowogrocki, G. (15 November 1980). "The low-temperature forms of some M1/3MIII(XO4)3 compounds: structure of triammonium indium(III) trisulfate". Acta Crystallographica Section B 36 (11): 2517–2519. doi:10.1107/S0567740880009338. 
  26. Perret, R.; Couchot, P. (June 1972). "Preparation et caracterisation cristallographique des sulfates et seleniates doubles anhydres d'indium M1In(XO4)2" (in fr). Journal of the Less Common Metals 27 (3): 333–338. doi:10.1016/0022-5088(72)90065-3. 
  27. 27.0 27.1 Beattie, James K.; Best, Stephen P.; Skelton, Brian W.; White, Allan H. (1981). "Structural studies on the caesium alums, CsM III [SO4]2•12H2O". Journal of the Chemical Society, Dalton Transactions (10): 2105–2111. doi:10.1039/DT9810002105. 
  28. Armstrong, Robert S.; Berry, Andrew J.; Cole, Bradley D.; Nugent, Kerry W. (1997). "Chromium luminescence as a probe of site effects in the alum lattice". Journal of the Chemical Society, Dalton Transactions (3): 363–366. doi:10.1039/A605705E. 
  29. Busev, A.I. (22 October 2013). The Analytical Chemistry of Indium. Elsevier. p. 5. ISBN 9781483149554. 
  30. 30.0 30.1 Ekeley, John B.; Potratz, Herbert A. (June 1936). "Some Double Salts of Indium and Organic Bases". Journal of the American Chemical Society 58 (6): 907–909. doi:10.1021/ja01297a016. 
  31. Fimland, B. O.; Svare, I (1 September 1987). "NMR and dielectric studies of NH4+ motion in some ammonium alums". Physica Scripta 36 (3): 559–562. doi:10.1088/0031-8949/36/3/031. Bibcode1987PhyS...36..559F. 
  32. The Encyclopædia Britannica: A Dictionary of Arts, Sciences, and General Literature. 5. 1888. p. 533. Retrieved 3 June 2015. 
  33. Bailey, W. C.; Story, H. S. (1973). "Nuclear quadrupole coupling of 115In in NH4In(SO4)2•12H2O". The Journal of Chemical Physics 58 (3): 1255–1256. doi:10.1063/1.1679317. Bibcode1973JChPh..58.1255B. 
  34. Navalgund, R. R.; Gupta, L. C. (1 September 1975). "EPR of Cr3+ in Methyl Ammonium Indium Sulfate Dodecahydrate". Physica Status Solidi B 71 (1): K87–K90. doi:10.1002/pssb.2220710161. Bibcode1975PSSBR..71...87N. 
  35. Purkayastha, B.C.; Das, H.B. (1 February 1963). "A STUDY ON THE PROBABLE EXISTENCE OF POTASSIUM INDIUM ALUM WITH RADIOACTIVE NUCLEI. PART I". Journal of the Indian Chemical Society 40. 
  36. Ivanovski, Vladimir; Petruševski, Vladimir M.; Šoptrajanov, Bojan (April 1999). "Vibrational spectra of hexaaqua complexes.". Vibrational Spectroscopy 19 (2): 425–429. doi:10.1016/S0924-2031(98)00068-X. 
  37. "inorganic Materials Database". 
  38. "Inorganic Materials Database". 
  39. "Inorganic Materials Database". 
  40. Fedorov, P.I.; Lovetskaya, G.A.; Starikova, Z.A.; Vlaskin, O.I. (November 1983). "[Study of zinc- and cadmium sulfates interaction with indium sulfate in aqueous solution at 25 deg C]". Zhurnal Neorganicheskoj Khimii 28 (11): 2962–2965. 
  41. Mukhatarova, N. N.; Rastsvetaeva, R. K.; Ilyukhin, V. V.; Belov, N. V. (March 1979). "Crystal structure of KIn(SO4)2·H2O". Soviet Physics Doklady 24: 140. Bibcode1979SPhD...24..140M. 
  42. 42.0 42.1 Petrosyants, S. P.; Ilyukhin, A. B.; Ketsko, V. A. (November 2006). "Supramolecular compounds of indium sulfates with nitrogen-containing cations". Russian Journal of Coordination Chemistry 32 (11): 777–783. doi:10.1134/s1070328406110029. 
  43. Tian, Zhen-Fen (March 2009). "Solvothermal Synthesis and Characterization of One-dimensional Chained Indium-Sulfate". Chemical Journal of Chinese Universities. 
  44. Shen, Fwu Ming; Lush, Shie Fu (15 September 2010). "Tri-µ-sulfato-κ6O:O'-bis[aqua(1,10-phenanthroline- κ2N,N')indium(III) dihydrate"]. Acta Crystallographica Section E 66 (10): m1260–m1261. doi:10.1107/S1600536810036330. PMID 21587408. PMC 2983182. Retrieved 3 June 2015. 
  45. Olapinski, H.; Weidlein, J. (June 1973). "Bis(dialkylmetall)sulfate der elemente gallium, indium und thallium". Journal of Organometallic Chemistry 54: 87–93. doi:10.1016/s0022-328x(00)84995-5. 
  46. Kartzmark, Elinor M. (August 1977). "Double salts of indium trichloride with the alkali chlorides, with ammonium chloride, and with indium sulfate". Canadian Journal of Chemistry 55 (15): 2792–2798. doi:10.1139/v77-388. 
  47. Dmitriev, V.S.; Malinov, S.A.; Dubovitskaya, L.G.; Smirnov, V.A. (September 1986). "Vzaimodejstvie metallicheskogo indiya s sul'fatom indiya(3)" (in ru). Zhurnal Neorganicheskoj Khimii 31 (9): 2372–2377. ISSN 0044-457X. 
  48. Kozin, L.F.; Egorova, A.G. (May 1982). "Sul'fat odnovalentnogo indiya, ego sintez i svojstva" (in ru). Zhurnal Obshchej Khimii 52 (5): 1020–1024. ISSN 0044-460X. 
  49. Downs, A. J. (31 May 1993). Chemistry of Aluminium, Gallium, Indium, and Thallium. Springer. p. 211. ISBN 9780751401035. 
  50. Schwarz-Schampera, Ulrich; Herzig, Peter M. (14 March 2013). Indium: Geology, Mineralogy, and Economics. Springer Science & Business Media. p. 171. ISBN 9783662050767. 
  51. "Indium Corp. In2(SO4)3 Indium Sulfate Anhydrous". 
  52. Bradley, David (2 July 2008). "Health Benefits of Indium". 
  53. Bradley, W.E. (December 1953). "The Surface-Barrier Transistor: Part I-Principles of the Surface-Barrier Transistor". Proceedings of the IRE 41 (12): 1702–1706. doi:10.1109/JRPROC.1953.274351. 
  54. "Philco Claims Its Transistor Outperforms Others Now In Use". Wall Street Journal: p. 4. 4 December 1953. 
  55. "Electroplated Transistors Announced". Electronics Magazine. January 1954.