Chemical Industry Tips – Indium

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In 1863, F. Reich and H.T. Richter in Germany discovered indium using spectroscopy. It is an element of group 3A in period 5, with the symbol In. Indium is one of the rare elements; it occurs in trace amounts mainly in cassiterite and sphalerite. It is a silver-white metal that is malleable, softer than aluminum, soluble in acids or bases, does not decompose water, and is quite stable in air. When burned, it produces a bright purple flame. Substances that can form covalent bonds rather than ionic bonds in chemical reactions are mainly compounds in the +III oxidation state and are non-toxic. Indium is commonly used as a coating for bearings; it can form brazed and low-temperature welded alloys with various metals, and is also frequently used as a material in electronic technologies such as semiconductors and electric light sources. Indium can be obtained from enriched sphalerite through chemical or electrolytic methods; Japan ranks first in indium production, followed by the United Kingdom, Colombia, and Peru.