What Is Indium?
Indium is a metallic element belonging to genus 13 of the periodic table, with the element symbol In and atomic number 49.
It has a density of 7.3 and a melting point of 156.4°C, which is quite low for a metal. Indium is named after the word Indigo because of the dark blue color of its emission spectrum.
It does not occur naturally as a single mineral but is found in small amounts in sulfides, primarily in flash zinc ore, and is recovered as a byproduct of zinc and lead smelting. It is one of the rarest and most precious metals. Despite its scarcity, its demand is growing, making its availability and cost an issue.
| Chemical Formula | In |
| Atomic Number | 49 |
| English Name | Indium |
| Molecular Weight | 114.818 |
| Melting Point | 156.6°C |
Uses of Indium
The main applications of Indium are liquid crystal displays and touch panels. Due to its structure, LCD panels require transparent electrodes, and indium tin oxide is used for these transparent electrodes. Indium tin oxide, commonly known as ITO, is a compound of indium oxide (In2O3), an oxide of indium, and tin oxide (SnO2).
Thin films (ITO films) made of indium tin oxide (ITO) have both visible light transmittance and electrical conductivity and are often used as transparent electrodes in LCD panels. In addition, indium can be doped into silicon and germanium to make p-type semiconductors.
Indium is also soft and ductile even at room temperature, making it very easy to bond to glass and metals. This makes it useful as a sealing material that can be used in low-temperature environments and as a solder for low-melting-point alloys.
Properties of Indium
Physical properties are band blue-white or silver-gray and soft enough to be cut with a knife. It is very stable in air at room temperature. Chemically, it is easily attacked by acids but is stable against alkalis.
Compounds of indium include indium oxide, indium phosphide, indium arsenide, and indium antimonide. Indium also exists in two mass numbers, 113 and 115, with 113 being a stable isotope and 115 being a radioactive isotope.
However, in nature, indium with a mass number of 115 accounts for about 95% of the total mass of indium, making it an unusual element in that it is more abundant as a radioactive isotope than as a stable isotope. However, radioactive isotopes with a mass number of 115 have an extremely long half-life of 441 trillion years and can almost be called stable isotopes.
Indium is therefore used in a wide variety of electronic components, but its radioactivity has never been a problem.
Other Information About Indium
1. Dangers of Indium
Deaths from interstitial pneumonia have previously been reported for ITO made from indium, and several cases of interstitial pneumonia have been reported among workers who handle ITO. In response, the Ministry of Health, Labour and Welfare (MHLW) announced in 2010 measures to prevent health problems due to work involving the handling of indium and tin oxides.
2. Production of Indium
Mines in Hokkaido, Japan, used to be the world’s largest producer of indium, but now China is the largest producer. Other countries with significant production include South Korea, Canada, and Japan.
However, the rapid increase in the number of indium mining sites and processing plants to meet modern demand has led to environmental destruction. Therefore, measures are being taken in Japan to promote the recycling of indium and the use of alternative materials.