Indium (In) - Properties, Applications

Topics Covered

Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties


Indium is a chemical element with ‘In’ as its symbol. It belongs to group 13 and has the atomic number 49.

Indium is very soft with high plasticity, malleability and ductility. It has good corrosion resistance to water and alkalis. It generally occurs within iron, lead, zinc, and copper ores. It is stable in air but dissolves in acids. It burns with a violet flame when heated above its melting point.

Canada is the leading producer of indium.

Chemical Properties

The chemical properties of indium are provided in the table below.

Chemical Data
CAS number 7440-74-6
Thermal neutron cross section 196 barns/atom
Electrode potential -0.340 V
Ionic radius 0.810 Å
Electronegativity 1.78
X-ray absorption edge 0.44397 Å
Electrochemical equivalent 1.4 g/A/h

Physical Properties

The following table discusses the physical properties of indium.

Properties Metric Imperial
Density 6.916 g/cm3 0.2499 lb/in3
Melting point 156°C 313°F
Boiling point 2000°C 3632°F

Mechanical Properties

The mechanical properties of indium are tabulated below.

Properties Metric Imperial
Tensile strength 4.50 MPa 653 psi
Modulus of elasticity 12.7 GPa 1840 ksi
Shear modulus 4.40 GPa 638 ksi
Hardness, Brinell 0.9 0.9
Hardness, Vickers ≤ 10 ≤ 10

Thermal Properties

The thermal properties of indium are tabulated below.

Properties Metric Imperial
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


The following are the application areas of indium:

  • Rectifiers
  • Solar cells
  • Thermistors
  • Semiconductors
  • Photoconductors
  • 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.

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