Deep freezing iron-based materials makes them both magnetic and superconducting
phys.org
phys.org
According to the sometimes ever-reliable Wikipedia [0], the cost of this material is probably dominated by the Rubidium at $15,500/kg.
It is a real privilege to watch the ever-quickening march of science in the 21st century. We're surrounded by so many miracles it is easy to overlook them.
[0] https://en.wikipedia.org/wiki/Prices_of_chemical_elements
When thinking about materials science, it is worth reflecting that the periodic table is very large but we produce very small amounts of most of it. In a bad year a country's annual consumption on Osmium could be smuggled in a small suitcase.
Now they decay into Neptunium. Funnily the more stable Americium delays into the less stable Neptunium, which has a half-life of 2.5 days before by alpha-decay decay into Plutonium with a half-life of 24,000 years. The stable Neptunium has a half-life of 2,144,000 years so that's safe.
Really throw a dental apron over it and the radioactivity should be fine (IAMNAD!!!), and a lead lined box should make it completely harmless. I think your sleep hygiene will have a larger effect on your health.
Now, as a trade good, I don't know how liquid the market is for Americium and how much purity matters, but it is definitely storable.
PS- lead if it can absorb alpha particle becomes Radon, which while not great for you, in trace amounts isn't terrible as many homes have it and their are limits for it etc.
[1] https://www.epa.gov/radtown/americium-ionization-smoke-detec...
That decay also emits a gamma ray as a byproduct.
The energy given off by these gamma rays is actually significant at 59.5 keV. For example, let's assume you have $1500 in americium-241 in your mattress. At $1500/gram, that's one gram. With a specific activity of 3.43 Ci/g, that gram has about 3.66×10^15 decays in a 8 hour night. At 59.5 keV per decay the total gamma ray energy is about 35 J, or 500 mSv for a 70kg person. That's equal to 25 full body CT scans, or the yearly occupational dose limit, every night.
Smoke detectors typically contain about a microgram of americium-241, so that translates to a nightly dose of 0.5 μSv, or a yearly dose of 550 μSv. That's about a quarter of the natural background dose. It's also the amount of radiation emitted by the smoke detector, not what you receive. At an average distance of 8 meters, you'll receive just 1/100th of that.
Although these inventions seem to rarely get much actual use. Although I can't find it, I saw an HN comment a few months ago about how ~dozens of interesting inventions hit the HN frontpage every year...and barely any of them turn into anything resembling a product.
So, beyond "overlooking" them, there's a cynicism that comes from seeing hundreds of new developments announced and then never deployed.
It is often for similar reasons - seems promising, but once you really dig into it there is a more economical alternative, or there is some difficulty in scaling/productionizing the process somewhere, or no one involved is able to connect with the right manufacturer/funder/customer/sales person because life.
It does open up new ‘hmm, what if’ options for further research though (as unlike many startups the things learned are often written up and eventually shared in a way that can be used by others later). If patents are acquired, in 20-30 years that may make it a now solvable problem for someone else as they can leverage the work without paying the cost.
But yes, if you’re looking at any of these announcements as something useful to you in the future instead of like a startup talking about the cool product they’ll eventually build - it’s going to be a rough ride.
I'm a bit confused by this, I thought that superconductivity is a 'yes or no' property, but here it is 'weakened', what does it mean in this context ?
Is it that the material is either superconductor or magnetic, but not both at the same time and place, and that it can be reversed ?
The arXiv link to the original research is https://arxiv.org/abs/2010.09901v2, and from Fig. 1, it follows that they are talking about a Type II superconductor, which does allow some magnetic field to pass through the bulk of it, in the form of vortices. Obviously, the volume occupied by the vortices is not superconductive, but they are shunted by the remaining bulk of the material, and therefore the resistance of the whole specimen is still zero.
What you're talking about is applying a magnetic field, which I'd argue is you're doing something to fuck with it, but if we're talking just lower the temperature and check its resistivity, then superconductivity is a yes or no state.
It is common to have pockets of non-superconducting material in superconductors. If they get too big in the wrong places then you quench.
Applied magnetic fields are common because, unsurprisingly, superconductors often find themselves used to make large magnetic fields without having to pay the electric company or cooling ohmic losses. Some applications can get by with just one magnet. Many others cannot.
I'm talking about a material that doesn't have any kind of phase segregation. In that case, the superconductive phase it 100% a "yes or no" property and that's that.
You're wrong.
Superconductivity is generally a "yes or no" property like you said, there's no phase coexistence within the material of a superconductive and regular conductor phase (unless an applied magnetic field is present, in which case there is latent heat).
Trying to imagine how an object in space made mostly of iron moving around in the coldest parts of the universe might act or interact with other objects around it. Seems like if it is cold enough and there is enough metal around it might force some clumping of material.
Maybe nothing happens or it can't because where space is that cold there is also not much there to interact with? I am a casual consumer of science info, I don't know anything really. Just thinking out loud.
Not sure magnetic fields reach between planets, but between a planet and a moon?
Got me thinking about it again.
Sometimes the Hacker News "de-click-bait filter" removes meaning from titles.
"WHY deep freezing iron-based materials makes them both magnetic and superconducting"