Indium has several industrial applications due to its physical and chemical properties. The following article provides information on its uses.
Indium is a rare metallic element, which is almost three times as abundant as silver in the Earth’s crust. It was added to the periodic table as its 49th element, and was discovered in 1863 by German scientists, Ferdinand Reich and Hieronymous Theodor Richter.
The name ‘indium’ is derived from the indigo color spectrum of this element, as observed in the spectral line. Chemically represented by the symbol In, this element has a lustrous silvery-white color. Owing to its malleability and ductility properties, it is extensively used in fabricating works.
Even at temperatures close to absolute zero, it can easily retain its softness, which makes it an obvious choice for many cryogenics and vacuum applications. Over the years, its use has increased drastically in the consumer electronics industry. Here are some of its physical properties in a tabulated form.
| Physical Properties | |
| Atomic weight | 114.82 |
| Crystal structure | Face-centered Tetragonal |
| Melting point | 156.6°C |
| Boiling point | 2080°C |
| Coefficient of thermal expansion | 28.47 kJ/kg |
| Latent heat of vaporization | 1959.42 kJ/kg |
| Thermal conductivity | 83.7 W/m/K at 0°C |
| Electrochemical equivalent | Valence 3, 396.4 µg/C |
| Stable isotopes | 113In, 115In |
Uses
The boom in the semiconductor industry since the last few decades, created the demand for extensive usage of indium in a variety of products like chips, transistors, and electronic appliances. Indium tin oxide (ITO), an oxide of indium, is widely used in the manufacturing of LCD screens. In fact, 50% of this metal is used in the production of liquid crystal displays. Besides being an important part of computer screens, LCDs are also extensively used in GPS receivers, cameras, PDAs, answering machines, cell phones, and other various setups. Due to its increased demand in consumer electronics industry, the price of this metal has shot up by many hundreds of dollars per kilogram.
It is commonly used in electrical components such as infrared detectors, high speed transistors, and photo-voltaic devices. Due to its low melting point and the ability to conduct electricity, it is used in the making of solders and alloys.
This metal also finds extensive use in the coating of glasses. Although such coatings are transparent, they reflect the infrared rays. These are used in aircraft windows, architectural windows, doors, refrigerators, and ovens.
Indium tin oxide is popularly used in low pressure sodium lamps. In nuclear reactors, indium’s neutrons are used in the control rods of reactors. In the field of nuclear medicine, indium leukocyte scintigraphy is used for monitoring the function of white blood cells. Here are some other uses of this metallic element:
- Indium oxide and indium tin oxide are used as coatings for electroluminescent panels.
- Indium antimonide, indium phosphide, and indium nitride are some of the popular semiconductor materials in the industry.
- This element is also used in LED lights and laser diodes.
- It is used as a solder alloy due to its ability to fill the difference in coefficient of thermal expansion (CTE) of two different metals, which causes breakage between metal joints, due to contraction and expansion.
In the coming years, it can be predicted that this metal will be used extensively, owing to the popularity of LCD screens in every type of media setup. However, its supply, as well as the price would be dependent on its commercial availability. China accounts for 60% of the world’s production of this metal, and the US relies on it and other countries, for its indium requirements.