For those of you that want to produce thin-film deposits of strange materials, this could be just the thing you’ve been waiting for. Gallium is an interesting metal, given that it’s molten at around 29°C and doesn’t seem to be poisonous, unlike Mercury which is best to avoid (even though Mercury used to be an essential metal for tooth-filling before UV-setting resins came along). The full article is at Gizmodo so best read that and follow the links if you’re interested, but I’ll extract a few bits here.
The basic process, if I’ve understood it correctly, is that we need to get the target metal dissolved in the Gallium to make an alloy. If the metal is more active than Gallium (and a lot are) then that metal will preferentially oxidise at the surface of the (liquid) alloy making a layer that could be a few atoms thick up to several nm thick – basically the same sort of thickness as that metal would normally have on its surface. To transfer the oxide layer to a substrate, simply push the (squeaky-clean) substrate down on to the surface of the alloy and the oxide layer will preferentially stick to the substrate.
With scale-up, this could give better and cheaper PVs, batteries and indeed any technology where thin films of an oxide are required. With a change of atmosphere, it’s possible that this could also produce thin films of sulphides too. Since it doesn’t need vacuum or high temperatures, the process should be very cheap where it can be used.
Some quotes from the article:
Researchers from RMIT University have discovered a simple technique to make atomically thin flakes of material. The breakthrough, published in Science, is expected to lead to faster, more energy efficient electronics.
Using a surprisingly simple method, metals are dissolved in liquid metal and the resulting super-thin oxide layer is peeled off.
The technique is predicted to work with about one-third of the periodic table and some of those elements create semiconducting or dielectric materials as oxide layers.
Hafnium oxide, an insulating material used in semi-conductors, with a thickness of only three atoms has been produced with this technique. That’s approximately five to ten times thinner than hafnium oxide layers produced with previous techniques.
This research was led by Professor Kourosh Kalantar-zadeh and Dr Torben Daeneke from RMIT’s School of Engineering who experimented with the technique for the last 18 months.
The materials produced by this technique are useful for more than just electronics. Some of the oxide layers can be used in batteries or as catalysts.
The research is funded by the Australian Research Council Centre for Future Low-Energy Electronics Technologies (FLEET).
DOI (Science: 10.1126/science.aao4249)