One of the characteristic properties of gallium is a long period of liquid state: the metal melts at t = 29.76°C and boils at t = 2,203.85°C. Thus, it retains its liquid form in a very wide temperature range of 2,174.09°C. At room temperature, the metal is resistant to oxidation, but when heated, it reacts actively with oxygen, as well as with iodine and sulfur. It slowly reacts with nitric and perchloric acid, and quickly dissolves in sulfuric and hydrochloric acid.
When in contact with aluminum and his alloys gallium penetrates the intercrystalline lattice of the metal, which leads to the destruction of the metal. For example, if an aluminum can is partially covered with Ga, it will not only begin to oxidize immediately, but also, after a short reaction, it will easily crumble in the hands. Moreover, gallium will act as a classic catalyst here: like mercury, it will turn aluminum into liquid amalgam, but it will not be consumed during the reaction process.
The unique characteristics of gallium were not in demand for many years, but after the discovery of its semiconductor properties, the situation changed dramatically. Back in 1990, global gallium production was only 6.5 tons per year, in 2008 it was already 270 tons, and in 2022 it was more than 430 tons. The sharpest increase in demand for Ga occurred in the early 2000s, when mobile phone production and fiber-optic communications began to develop rapidly. It was during this period that most of the gallium production facilities were built. It is surprising that despite the continuous growth in demand for metal, the world's Ga mining and processing capacity is considered excessive: according to the US Geological Research Survey, existing enterprises can produce more than 480 tons per year (which exceeds consumption by more than 10%).
Without Ga, technologies like Wi-Fi, Bluetooth, and mobile communication would not exist. Gallium arsenide (GaAs) chips are widely used in wireless networks, and gallium nitride (GaN) chips are widely used in chargers and electric vehicles. Microprocessor electronics are the main application of Ga — it consumes 96.7% of the world's metal production.
Gallium arsenide is a semiconductor like silicon, but when working at ultra-high frequencies, it provides better communication and reduces noise. In addition, gallium electrons move five times faster than silicon, which makes it possible to significantly increase the speed of signal transmission. Until some time, GaAs was used to make only unique, expensive parts, for example, solar cells for space stations. But with the advent of 3G and 4G communication standards, the demand for Ga has increased by more than 10 times (and the development of 5G without it would be impossible at all, since only gallium can provide the required data exchange rate). Today, more than half of the gallium produced is spent on the production of 3G/4G chips.
Another area of application is the production of LEDs. Ga compounds with other elements make it possible to obtain “radiant” elements with a different color spectrum. For example, gallium arsenide or its alloy with aluminum (AlGaAs) is used for infrared radiation, gallium phosphide with aluminum and indium (AlGaP and AlGaInP) is used for green radiation, and indium gallium nitride (InGaN) is used for violet radiation.
Gallium nitride is widely used in the manufacture of liquid crystal displays, components for electrical switchgears, industrial control systems, microwave sources, and base stations for wireless networks.
The production of thin-film photovoltaic cells, including those used to absorb solar radiation, is considered to be a potentially growing market for gallium. But in addition, there is another industry that can provide Ga with another sharp jump in demand: so-called wearable electronics — devices that can create a whole with the human body.
To manufacture such products, liquid wires are needed, which in this state will not only retain their electrical conductivity, but also will not prevent the penetration of light, heat and moisture. And if it is sufficient to use a transparent polymer base to achieve the required water and light transmittance, then only metal is suitable for the desired heat dissipation. The solution was gallium, placed in an elastic shell of polymers.
Single devices with liquid wires are already available to some users. Unfortunately, so far it is mainly for their developers and interested scientists. For example, in prototyped elements of virtual reality systems, gallium encapsulated in a polymer shell is used to transmit information about tactile sensations.
.jpg)