Iridium

Atomic no.
Relative Atomic Mass
Melting Point
Boiling Point
Density
Electrical Resistivity
Abundance 
Thermal Conductivity
77
192.217
2466°C
4130°C
22420 kgm-3
47.1 nΩm
0.001 ppm
147 W/m/K 

Iridium was first discovered in 1803 by Smithson Tennant, when he was dissolving a sample of platinum in strong acid and noticed some black solid left in the beaker. It was later found to be a mixture of osmium and iridium, the two densest elements.

One of iridium’s useful properties, is that it is extremely corrosion resistant, as shown in this experiment it did not react with a mixture of hydrochloric and nitric acid, which is so strong it dissolves platinum. Iridium also has a very high melting point of 2700 degrees celsius, and even at these high temperatures it still does not oxidise.

There are downsides to iridium though, being rarest naturally occuring metal on Earth, it isn’t cheap. Coming in at the same price as gold, we will only see it used in niche situations. 

Iridium has also found a use in electronic spin devices, such as hard drive disks, solid state drives are slowly taking over. On the other hand, a new form of RAM is being developed, which will be faster than our current RAM, that utilises spin electronics, and so iridium will be a key element used here.

Iridium has also found a use in creating an alloy used in the tips of spark plugs in petrol engines. The high temperatures required to ignite fuel, means that iridium is a great candidate to use here, and also the corrosion resistance at high temperatures means that iridium alloy spark plugs have a very long lifetime. With the aim of cutting down carbon emissions, electric cars will become more popular which do not require spark plugs, and so iridium’s demand will likely decrease for this use.

Iridium is also used to make crucibles for growing crystals of, for example yttrium aluminium garnet crystals used to make lasers for medical procedures and laser cutting. LEDs are also grown on sapphire wafers in these iridium crucibles.

Iridium has also found a use in spintronic devices, such as hard drive disks, but solid state drives, an alternative to these disks, are slowly taking over. On the other hand, a new form of RAM, magnetic RAM, is being developed, which will be faster than our current RAM, that utilises spintronics, and so iridium will likely be a key element used here.

It is clearly very difficult to predict the future of the demand and uses of iridium. However, with the EU funding a project with 2 million euros between 2013 and 2017 looking for alternative materials to use instead of iridium in many more spintronic devices, it is clear that some people think the future of iridium is important.

Ross Milverton

© 2020 Lipmann Walton & Co. Ltd

reach 1.png
iso.png