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Comment by onetimeuse92304 | Hacker News Reader

> One major problem that Re6Se8Cl2 faces is that rhenium is one of the rarest elements on Earth. This makes Re6Se8Cl2 very expensive and unlikely to ever make its way into a commercial product.

I call BS. It is rare, true. But it is found in reasonable concentrations in some minerals (alongside molybdenum) that are already being mined and we just need to learn to extract rhenium out of it. For high perf semiconductors you only need microscopic amounts of it anyway.

As to costs, majority of the costs are not in substrates anyway, however costly they are. The costs are in IP and in processing. I suspect even if silicon was as expensive as gold it would not meaningfully change the cost of current high-end CPUs that go into our phones.

(edited, I mistakenly wrote ruthenium where I meant rhenium)

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Its concentration in minerals is not reasonable, but extremely small.

The yearly production per human is a barely visible grain with a volume of about a quarter of a cubic millimeter. If each human would want to have a ring of rhenium, that would need all the global production accumulated during one thousand years.

All of it is heavily contended for various applications like gas turbine blades, so the price is in the same range as for platinum-group elements, which are in fact much more abundant.

If the semiconductor layers would have thicknesses in the tens of nanometer range, i.e. they would be deposited on some crystallographically compatible substrate, then such a semiconductor might be usable for expensive devices.

Nevertheless, developing a deposition method that can recycle all the non-deposited rhenium may be not easy. The deposition methods normally used frequently deposit far more substance on the equipment walls than on the semiconductor wafer. When depositing pure inert metals like gold or platinum, there are relatively easy methods to recover them, e.g. by dissolving in acid everything else. Such a complex substance containing rhenium might be obtained from a chemical reaction during the deposition, but it may be difficult to find precursors that are also easy to recycle.

> All of it is heavily contended for various applications like gas turbine blades […]

Then why does it only cost $1 per gram?

[1] https://pubs.usgs.gov/periodicals/mcs2021/mcs2021-rhenium.pd...

That low price was only in 2020, as a result of the huge air traffic decrease caused by COVID-19.

The price of rhenium fluctuates wildly and a few years ago there was a maximum at $10 per gram.

It is unlikely that it will ever return to the COVID-19 price.

The problem with rhenium is not the current price, but the minuscule production, for which there is very little hope that it could be increased much.

If instead of being used in a few military and commercial airplanes and in a few industrial applications, like thermocouples or catalysts, there would be demand to use it in something used by everybody, the price would increase quickly.

Why do you think there's little hope on increasing production?

At $10/gram, of course there isn’t much production?

Price of gold is ~$60/gram, so this is not especially expensive in the grand scheme of rare metals even if it's significantly more expensive than copper.

Considering its rarity and industrial usage, it’s quite a steal even.

> If instead of being used in a few military and commercial airplanes and in a few industrial applications [...]

Wait, above you said it's heavily contended...

Presumably given its scarcity any application makes it heavily contended

53 tons of it are produces annually... Surely not "any application" uses up 53 tons per year.

Here, I see the problem with your logic.

> The price of rhenium fluctuates wildly and a few years ago there was a maximum at $10 per gram.

You lost sight of the simple fact I mentioned, you only need a very small amount of it and you add it to a CPU that costs hundreds of dollars already. So the impact on the cost of the CPU would be negligible.

Even at the highest cost of rhenium you have mentioned, even if you needed a full gram of it (which I don't believe, this is going to be more like milligrams or even micrograms), you still only change the cost of the CPU slightly, at most.

This before you account for inevitable improvements in obtaining the Rhenium itself.

The GP's point is that if people start using enough of it, the price will easily explode into several thousands or even millions per gram.

It all depends on a lot of details that haven't yet been quantified here. And the recycling the GP talks about is a huge one.

My intuition matches yours. It's abundant enough to find its way into alloys for jet engine blades at single digit percentages: https://www.thenakedscientists.com/articles/science-features... And if used in chips, you don't need to make the full substrate with this material, just a few hundred nanometers at the top, in the active area.

Exactly my point, you said it better than I did.

People don't have understanding of what expensive is. Even at hundreds or thousands of dollars per gram it could be pretty much irrelevant to the end result cost if you only need a layer that is couple nanometers in width.

The cost of the raw materials is a rounding error compared to all other aspects of semiconductor manufacturing.

The entire industry is a game of "value-add". The blank silicon wafers start out with effectively zero (or negative) value. The raw materials are worthless to the business. Only once validated features (process layers) begin to accumulate do those raw materials begin to inherit some sense of value.

Ruthenium is a bit different than Rhenium. But either way you can get it online. https://www.rwmmint.com/products/rhenium-metal

I meant rhenium. Don't know why I wrote ruthenium, that is obviously a mistake. Thanks for pointing it out.

I am glad you did because it led me on a Wiki chase and I learned new things :-)

Did you see some dishes no longer moldy?

Why would someone buy this? What can you do with a Rhenium ingot?

You can build the fastest semiconductor yet

You can be amazed of its density, but that is safer to do with the lighter, but much cheaper, tungsten.

Most chemical elements with atomic numbers equal or greater than that of lutetium are very slightly radioactive (with a few exceptions like iridium, gold, mercury and lead). Rhenium is one of the most radioactive of them, but it is several orders of magnitude less radioactive than thorium and uranium.

Nevertheless, its radioactivity is so weak that it can be handled safely with bare hands. Even so, making some jewelry kept permanently on the skin is unlikely to be a good idea.

> Rhenium is one of the most radioactive of them, but it is several orders of magnitude less radioactive than thorium and uranium.

Rhenium does have one stable isotope, which comprises 37,4% of naturally ocurring Rhenium. 62,6% is radioactive Rh-187 with a half-life of 10^10 years. That's a bit longer than U-235 or U-238.

But unlike uranium, Rh-187 decays into stable osmium.

Yeah, rhenium radioactivity is pretty much irrelevant for health.

I would worry more about radioactivity as a failure mode for these transistors. Given how fast these are and how few atoms are supposed to be there, the question is if a single atom in the lattice undergoing fission can

a) blow up the lattice enough to disrupt it

b) make it no longer perform the function because the atom that is there has different chemical properties

Once you have a periodic table display case, you would be amazed at how compelling it becomes to shop for element samples.

Hodl in case it becomes the next great semiconductor substrate?

Are you discounting the cost of development of technology to support the new semiconductor material? that along with it's rarity is what I suspect they're talking about.

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