Indium is a chemical element with symbol In and atomic number 49. It is a post-transition metal that makes up 0.21 parts per million of the Earth’s crust. Very soft and malleable, indium has a melting point higher than sodium and gallium, but lower than lithium and tin. Chemically, indium is similar to gallium and thallium, and it is largely intermediate between the two in terms of its properties.
Indium is a minor component in zinc sulfide ores and is produced as a byproduct of zinc refinement. It is most notably used in the semiconductor industry, in low-melting-point metal alloys such as solders, in soft-metal high-vacuum seals, and in the production of transparent conductive coatings of indium tin oxide (ITO) on glass.
Indium has no biological role, though its compounds are somewhat toxic when injected into the bloodstream. Most occupational exposure is through ingestion, from which indium compounds are not absorbed well, and inhalation, from which they are moderately absorbed.
|Thermal neutron cross section||196 barns/atom|
|Electrode potential||-0.340 V|
|Ionic radius||0.810 Å|
|X-ray absorption edge||0.44397 Å|
|Electrochemical equivalent||1.4 g/A/h|
|Density||6.916 g/cm3||0.2499 lb/in3|
|Tensile strength||4.50 MPa||653 psi|
|Modulus of elasticity||12.7 GPa||1840 ksi|
|Shear modulus||4.40 GPa||638 ksi|
|Hardness, Vickers||≤ 10||≤ 10|
|Thermal expansion co-efficient (@20-100°C/68-212°F)||33 µm/m°C||18.3 µin/in°F|
|Thermal conductivity||83.7 W/mK||581 BTU in/hr.ft².°F|
- Solar cells
- To dope germanium to make transistors
- To make mirrors, and low melting alloys
- To coat the bearings of high speed motors
- Alloying for low temperature solders and fuses
- As light filter in low-pressure sodium vapor lamps
- Electroplating for high-performance engine components.
- Used in the manufacturing of automobile bearings, which improves anti-seizure properties and moisture resistance.
- Used in semiconductor industries in the manufacturing of transistors, rectifiers, and diodes.
- Used in plating applications.
- Used in manufacturing of corrosive resistant mirrors.