Goldene Stumbled Upon
quietus writes:
Remember graphene, the single-atom-thick material nobody has managed to bring to production scale (yet)?
Problem with graphene -- and other 2D materials -- is that their atoms have always tended to cluster together to make nanoparticles instead. Instead of a clean sheet of material, you'll get a 3D blob, and a mournful look at the Star Trek poster on your lab wall.
Now scientists have managed to make such a 2D, single-atom, layer, using a fairly simple technique. This opens up the possibility of having a valid candidate for mass production.
The new technique was discovered through the well-honed scientific process of trying (and failing) to do something else. In this case, the investigators started out with a material containing atomic monolayers of silicon sandwiched between titanium carbide. The researchers' aim was to coat this electrically conductive ceramic with a thin layer of gold, at a high temperature, to make a contact. (Maybe someone of the team had plumbing problems at home.)
To their surprise, instead of a nice golden coat they ended up with intercalation, where one material in a layered structure is replaced by another. In this case, the silicon atoms were replaced with gold atoms. Some smart-ass noted that this meant they effectively had a 2D layer of gold atoms sandwiched in between layers of something else. Maybe, if we remove the titanium carbide?
How they got the idea is not clarified (an iaido practitioner in the ranks, one presumes), but the team turned to an etching technique used by ancient Japanese blacksmiths. While the process immediately showed promise, the researchers said that finding the exact formula involved months of trial and error, but no limbs were lost.
In the end, what was crucial was the solution and duration of application of the reagent (Murakami's etch) used, as well as complete darkness. That's because light hitting Murakami's reagent can produce cyanide, which dissolves gold. When trying to create a 2D gold sheet, having it dissolve is clearly an unwanted result.
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