 Discovery Information
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| Who: Ferdinand Reich, H. Richter |
| When: 1863 |
| Where: Germany |
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| Name Origin
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| From the indigo blue it shows in a spectroscope. |
| "Indium" in different languages. |
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| Sources
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| Found in certain zinc, copper, iron and lead ores. Canada is the leading producer of indium.
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| Around 75 tons are produced every year. |
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| Abundance
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| Universe: 0.0003 ppm (by weight) |
| Sun: 0.004 ppm (by weight) |
| Carbonaceous meteorite: 0.45 ppm |
| Earth's Crust: 0.049 ppm |
| Seawater: 1 x 10-7 ppm
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| Uses
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| The first large-scale application for indium was as a coating for bearings in high-performance aircraft engines during World
War II. Afterwards, production gradually increased as new uses were found in fusible alloys, solders, and electronics. In
the 1950s, tiny beads of it were used for the emitters and collectors of alloy junction transistors. In the middle and late
1980s, the development of indium phosphide semiconductors and indium tin oxide thin films for liquid crystal displays (LCD)
aroused much interest. By 1992, the thin-film application had become the largest end use.
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| Used to coat high speed bearings, in solar cells, mirrors, regulators in nuclear power, photo cells, the production of LCDs
(this accounts for the majority of world-wide usage), transistors and blood and lung research. Used in the manufacture of
low-melting-temperature alloys. An alloy consisting of 24% indium and 76% gallium is liquid at room temperature.
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| Indium cano be plated onto metals and evaporated onto glass which forms a mirror which is as good as those made with silver but has higher corrosion resistance.
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| History
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| Indium (named after the indigo line in its atomic spectrum) was discovered by Ferdinand Reich and Hieronymous Theodor Richter in 1863 while they were testing zinc ores with a spectrograph in search of thallium. It is interesting to note that most elements were discovered while searching for other elements. Richter went on to isolate
the metal in 1867.
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| Notes
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| The Earth is estimated to contain about 0.1 ppm of indium which means it is about as abundant as silver, although indium is in fact nearly three times more expensive by weight.
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| One unusual property of indium is that its most common isotope is slightly radioactive; it very slowly decays by beta emission to tin. This radioactivity is not considered hazardous, mainly because its half-life is 4.41 x 1014 years, four orders of magnitude larger than the age of the universe and nearly 50,000 times longer than that of natural thorium.
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| As a pure metal indium emits a high-pitched "cry" when it is bent. |
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| Hazards
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| Pure indium in metal form is considered non-toxic. However, all indium compounds should be regarded as highly toxic. Indium compounds damage the heart, kidney, and liver, and may be teratogenic. Indium trichloride (anhydrous) (InCl3) is quite toxic, while indium phosphide (InP) is both toxic and a suspected carcinogen.
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