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Properties

General data

Name, symbol, atomic number 

Gallium, Ga, 31

Element category

Metal

Melting point 

302.9 K (29.8 °C)

Boiling point 

2477 K (2204 °C)

Crystal structure 

Orthorhombic 

Density

5.904 g/cm³ (at 20 °C)

Mohs hardness

approx. 1.5

Physical properties

Stable semiconductor for numerous applications

Gallium is a silvery, shiny, soft metal from the boron group in the periodic table. It melts at just over 29.8 °C, i.e. a few degrees above room temperature. In its solid state, it is relatively soft and brittle. An unusual density distribution is also typical of gallium, as the density in the solid state is lower than in the liquid state. It forms stable semiconductor compounds such as gallium arsenide (GaAs) and gallium nitride (GaN). These have a high electron mobility and direct band gaps. This allows electronic and optoelectronic properties to be specifically controlled. These properties make gallium compounds particularly suitable for a wide range of applications: From light-emitting diodes (LEDs), photodetectors and solar cells to high-frequency transistors. This makes gallium indispensable for modern semiconductor and communication technologies.

Characteristic properties

Rare metal with unusual melting behavior

Gallium has a very low melting point of around 29.8 °C and therefore becomes liquid just above room temperature. This property is extremely unusual for metals and is one of the most striking characteristics of the element. 

In addition, the density of gallium is lower in the solid state than in the liquid state. This means that gallium expands during solidification and takes up more space in the solid state than in the molten state. Only a few elements exhibit this rare behavior, including antimony, bismuth, silicon, lithium and tellurium. 

Meaning and applications

Key raw material for modern semiconductor technologies

Today, gallium plays an important role in numerous civil, industrial and military technologies. Its semiconductor compounds such as gallium arsenide and gallium nitride, which are used in modern electronics, are particularly important. Gallium compounds offer advantages over the classic semiconductor material silicon, especially in high-frequency and power electronics: they enable higher frequencies, temperatures and voltages. With the expansion of 5G networks and other modern communication technologies, the importance of gallium continues to grow. The element is therefore now considered a strategically important raw material for the global semiconductor industry.