Gallium

Gallium is a soft, silvery metal with the chemical symbol Ga and atomic number 31. It belongs to group 13 of the periodic table, lying between aluminium and indium. Although relatively rare in nature, gallium has become an essential element in modern technology due to its unique physical and chemical properties, such as its ability to melt just above room temperature and its role in semiconductor applications.

Physical and Chemical Characteristics

Gallium is notable for its low melting point of approximately 29.76°C, which allows it to melt in the human hand, while it boils at about 2400°C, demonstrating an exceptionally wide liquid range. It does not occur as a free element in nature but is extracted as a by-product from the processing of bauxite and zinc ores. In appearance, it is a silvery-white metal that can wet glass and other surfaces, forming a mirror-like coating.
Chemically, gallium is stable in air and water but reacts with strong acids and alkalis. It readily forms compounds such as gallium(III) oxide (Ga₂O₃) and gallium arsenide (GaAs), both of which are critical to electronic and optoelectronic industries. Its density increases upon melting — an unusual characteristic among metals.

Occurrence and Production

Gallium is found in trace amounts in various minerals such as sphalerite and bauxite, typically at concentrations of less than 0.01%. The major producers of gallium include China, Japan, South Korea, Germany, and Kazakhstan. The extraction process involves recovering gallium from the residues left after aluminium or zinc refining.
Global production of refined gallium is measured in tens of tonnes per year, reflecting its rarity and the complexity of its extraction. Secondary production through recycling from electronic waste and manufacturing residues is becoming increasingly significant, driven by the rising demand for gallium-based semiconductors.

Everyday Applications

Although gallium is not encountered in its metallic form in daily life, its compounds play a vital role in everyday technology. Gallium-based materials are used in numerous consumer and industrial products that underpin modern lifestyles.

• LEDs and Displays: Gallium arsenide (GaAs) and gallium nitride (GaN) are key components in light-emitting diodes (LEDs) found in mobile phones, televisions, traffic lights, and general lighting. Their energy efficiency and long lifespan have helped replace traditional incandescent bulbs.
• Solar Panels: Gallium is used in gallium arsenide solar cells, which offer high efficiency and durability, making them ideal for satellites, space probes, and high-end terrestrial solar panels.
• Smartphones and Electronics: Gallium compounds are essential in high-frequency and high-speed electronic circuits found in smartphones, radar systems, and Wi-Fi routers. Gallium nitride transistors allow faster processing and reduced heat generation compared to silicon-based alternatives.
• Medical Devices: Gallium salts have been used in radiopharmaceuticals, such as gallium-67 citrate, which helps detect inflammation, infections, and tumours through medical imaging.
• Thermometers and Heat Transfer: Due to its non-toxic nature and low melting point, gallium serves as a safer substitute for mercury in thermometers and as a component in heat-transfer alloys.

Industrial and Technological Uses

In industry, gallium is prized for its semiconducting, optical, and thermal properties. Its principal applications are concentrated in optoelectronics, power electronics, and communications.

• Semiconductor Industry: Gallium arsenide (GaAs) and gallium nitride (GaN) are critical semiconductors that outperform silicon in high-frequency and high-power applications. They are integral to satellite communications, 5G networks, and microwave devices.
• Aerospace and Defence: The robustness and high-temperature performance of gallium-based semiconductors make them ideal for radar systems, missile guidance, and spacecraft communications.
• Optoelectronics: Gallium phosphide (GaP) and gallium nitride (GaN) are widely used in the manufacture of laser diodes and light sensors, supporting applications in barcode scanners, Blu-ray devices, and fibre-optic communications.
• Alloys and Materials Science: Gallium forms low-melting alloys, such as galinstan (a mixture of gallium, indium, and tin), which remains liquid at room temperature. Such alloys serve as heat-transfer fluids, coolant agents in nuclear reactors, and substitutes for toxic liquid metals.

Economic Importance

The economic value of gallium lies in its strategic role in high-technology industries. Although the volume of global production is small, its impact is disproportionally large. Demand for gallium continues to rise due to the expansion of renewable energy, electronics, and telecommunications sectors.

• Price and Supply: Gallium prices fluctuate based on demand for LEDs and semiconductors. The majority of global gallium supply is controlled by a few countries, particularly China, which has a dominant position in refining capacity.
• Strategic Material: Many nations classify gallium as a critical material due to its limited availability and essential use in advanced electronics and defence technologies.
• Recycling and Sustainability: Efforts are ongoing to improve recycling technologies for gallium from LED manufacturing waste and obsolete electronic devices. This is crucial to mitigate supply risks and environmental impacts.

Environmental and Safety Considerations

Gallium is considered relatively safe and non-toxic in comparison with heavy metals like mercury or cadmium. However, gallium compounds, particularly gallium arsenide, pose environmental and health hazards due to the presence of arsenic, a toxic element. Strict safety measures are implemented during manufacturing and disposal to prevent contamination.
Recycling gallium from industrial residues and electronic waste also contributes to environmental sustainability by reducing the need for new mining and minimising hazardous waste.

Future Prospects and Research

Gallium’s role in next-generation electronics and clean energy technologies continues to expand. Research focuses on developing gallium nitride (GaN)-based power devices that can operate at higher voltages and temperatures, improving energy efficiency in electric vehicles, renewable energy systems, and consumer electronics. Additionally, gallium oxide (Ga₂O₃) is emerging as a potential semiconductor for ultra-high-power devices.
Advancements in quantum computing, photonics, and artificial intelligence hardware are also expected to increase the strategic importance of gallium. Its combination of electronic versatility, efficiency, and thermal stability ensures that gallium will remain a cornerstone of technological progress in the coming decades.