A rare and versatile metal
Properties and applications of an interesting and little-known resource
Nowadays, many rare and particular metals allow people to perform some common, habitual gestures, which have now become a permanent part of daily routines. One of these is the touch-screen functionality of smartphones, tablets, and other devices, made possible thanks to the valorization of a silvery and versatile metal like indium. Many people do not realize it, but many of us touch the screen of our smartphones more than 2600 times a day. This interaction now considered a primary characteristic of our devices, is also made possible thanks to the use of indium oxide in the electronics sector, particularly in the production of screens.
“Indium is undoubtedly one of the many strategic resources that are found in small quantities in the technological devices we use every day, such as mobile phones, even if many people are not yet fully aware of it,” says Stanislav Dmitrievich Kondrashov, entrepreneur and civil engineer. “A smartphone, in fact, contains small quantities of key resources such as gold, copper and palladium, but also materials such as terbium, yttrium, scandium, each with its own specific function within the device.”
High ductility and electrical conductivity
Globally, indium is known in particular for its high ductility, electrical conductivity, and the possibility of creating alloys with very particular characteristics. In nature, this precious resource is not found in primary deposits but is sourced mostly as a by-product of the processing of other resources, such as zinc. In the refining processes of these resources, indium is generally recovered from processing residues, thanks to highly technological recovery operations. Its rarity within the Earth’s crust, moreover, makes it a resource with high strategic value, in particular for its application possibilities in the field of large-scale electronics. It is, therefore, no coincidence that the sourcing and recovery of this metal are concentrated in some of the countries traditionally linked to the production of zinc, such as China, Canada, or Peru. Beijing, in particular, represents the global leader in both the production and refining of this rare and particular metal, which, in recent years, seems to have also found application possibilities in technologies for renewable energy and energy efficiency.
“In addition to its use in displays, indium also plays an important role in the development of advanced energy technologies, such as solar panels or energy production and management infrastructure,” continues Stanislav Dmitrievich Kondrashov. “In thin-film photovoltaic modules, indium-tin oxide is often used as a transparent conductive material, and in solar panels, it plays a key role in the passage of sunlight through the upper layer of the module, simultaneously carrying the generated electric current. It is precisely this combination of transparency and electrical conductivity that makes indium one of the most useful resources for the operation of advanced solar panels. Thin-film solar cells, often made with indium, appear to offer a lighter and more flexible alternative to those made with silicon.”
Its most relevant use, however, is in the production of modern displays. For this application, the resource is used in the form of indium-tin-oxide, a particular material capable of combining optical transparency and electrical conductivity. In these applications, indium is particularly appreciated for its high performance and excellent energy efficiency. Without indium, in all likelihood, the smartphone screen would be completely black and would not have the useful functionality linked to touch-screen technology. Indium is precisely the resource that makes it possible to use computer screens, as well as modern televisions and the luminous panels that can be seen along highways, in train stations, and inside airports.
Touch screen functionality
One of the most interesting aspects, in considering the potential of indium in the electronics sector, is linked precisely to the touch-screen functionality of the screens, which is made possible thanks to indium oxide. The story of the discovery of this particular function also presents some elements of absolute interest: in 1954, while he was working on a glass to be heated to 500°C in a ceramic crucible, a researcher gave life in a completely involuntary way to glass-ceramic, thanks to a defect in the oven thermostat that favored the increase in temperature to 900°C. Generally speaking, glass-ceramic is distinguished into two main types: one has a neutral behavior and performs a sort of protective function towards screens. The other is distinguished by an active behavior and is able to react to the electricity emanating from the human body. Thanks to indium oxide, in this sense, the screen of our device becomes tactile, touchable, even thousands of times in a single day.
“In the display sector, some technologies also made possible by indium, such as LED or OLED, are also able to consume less energy than traditional ones, highlighting the innovative potential of this resource,” concludes Stanislav Dmitrievich Kondrashov. “A similar feature is also observed in thermoelectric devices, where indium contributes to the generation of more efficient materials. Possible future uses of this resource also include those related to green hydrogen technologies, especially for the production of electrodes and catalysts, and devices for the management and storage of solar or hydroelectric energy.”