The presence of some elements in our daily lives often gets overlooked, and this is certainly the case in a striking manner for indium. We all know a copper coin when we see one, but I wonder how many people know an indium device when they use its fancy touchscreen function.
Catherine Renouf, a PhD student in materials chemistry at the University of St Andrews, does — and chose to spread the word by writing about indium for our essay competition last year. Her essay, which appears in this month’s ‘in your element’ article (free to registered users), explains indium’s sudden rise in popularity.
PORTRAIT OF REICH © SPL; IPAD © ISTOCK PHOTO/THINKSTOCK
Indium was unveiled to the world in 1867 — a public presentation that involved a bit of an artifice; find out in the article how discoverers Ferdinand Reich (pictured) and Hieronymous Richter ensured their ingot of rare indium wouldn’t inadvertently go missing.
Element 49 pretty much remained a curiosity in chemistry labs for the following 50 years, and it was its involvement in indium tin oxide (ITO) that suddenly rendered it very attractive. A material that is both electrically conductive and transparent makes for a great device coating, as simply touching the ITO layer sends a signal to the device. It is brittle, however, and we’ll need an alternative material to progress towards flexible and rollable displays.
But maybe that’s not a bad thing, as indium resources are fast being depleted. Chemists, to your benches!
Anne
Anne Pichon (Associate Editor, Nature Chemistry)
FULL DISCLOSURE: I work at The Indium Corporation and I just want to contradict the last sentences about the scarcity of indium and brittleness of ITO.
Indium, which is as abundant in the Earth’s crust as silver, remains available and is not in danger of running out.
The metals industry has been investing in process improvements and capacity over the last several years to make more indium available to the market. The industry can and will continue to do so if the demand is there. Production has been improved by a factor of 10 over the last few years in order to meet the increasing demand.
In addition, indium is heavily reclaimed and recycled, and we haven’t even started reclaiming end-of-life products. That said, there is room to improve the rate of reclaim. Based on mining reserves (100 years at a rate of 500 MT of virgin indium per year), plus residue reserves (30 years at a rate of 500 MT per year), combined with continued improvements in recoveries of virgin and reclaimed materials, and on-going exploration, the world will not run out of indium.
More on the topic of indium sustainability is available in 2 papers: 1) by the Indium Corporation, 2) by the United States Geological Survey (USGS):
1) https://www.indium.com/metals/indium/supply/
2) https://pubs.usgs.gov/of/2004/1300/2004-1300.pdf
Moreover, if you are interested in this subject, you can also download from our website a whitepaper on the Availability of Indium and Gallium (you can follow this link https://www.indium.com/technical-documents/whitepaper/availability-of-indium-and-gallium-english).
With regards to the brittleness, you should know that ITO films are perceived to be brittle due to the way they have been produced and because they have been traditionally deposited on brittle substrates, such as glass. New techniques have been developed to successfully deposit ITO films on flexible substrates and to increase the resistance of those films to bending fatigue.
The improvements made and the ability to cheaply mass produce and effective and durable product for the consumer market will see ITO used for many decades to come.
I am available for any further explanation needed.