Chemical element

Applications:

Cody'sLab had a nice 5 video series on making it at home! But the United States Government asked him to take it down as suggested at Video "What's Been Going On With Cody'sLab? by Cody'sLab (2019)" at youtu.be/x1mv0vwb08Y?t=84.

Here's a copy online as of 2020: www.youtube.com/watch?v=bCXB6BdMh9Y

Used in:

4 K. Enough for to make "low temperature superconductors" like regular metals superconducting, e.g. the superconducting temperature of aluminum if 1.2 K.

Contrast with liquid nitrogen, which is much cheaper but only goes to 77K.

Surprisingly, it can also become a superfluid even though each atom is a fermion! This is because of Cooper pair formation, just like in superconductors, but the transition happens at lower temperatures than superfluid helium-4, which is a boson.

aps.org/publications/apsnews/202110/history.cfm: October 1972: Publication of Discovery of Superfluid Helium-3 contains comments on the seminal paper and a graph which we must steal.

Also sometimes called helium II, in contrast to helium I, which is the non-superfluid liquid helium phase.

The layered one.

A single layer of graphite.

77K. Low enough for "high temperature superconductors" such as yttrium barium copper oxide, but for "low temperature superconductors", you need to go much lower, typically with liquid helium, which is likely much more expensive. TODO by how much?

piezoelectric, and notably used in quartz clock.

An alloy of iron and carbon. Because such allys have had such incredible historical importance due to their different properties, different phases of Fe-C have well known names such as steel

A phase of Fe-C characterized by the low ammount of carbon.

This is apparently the most important III-V semiconductor, it seems to actually have some applications, see also: gallium arsenide vs silicon.

Trying to use gallium arsenide was Seymour Cray's fatal last flaw as mentioned at The Supermen: The Story of Seymour Cray by Charles J. Murray (1997).

The Supermen: The Story of Seymour Cray by Charles J. Murray (1997) page 4 mentions:

Cray wanted his new machine to employ circuits made from a material called gallium arsenide. Gallium arsenide had achieved limited success, particularly in satellite communications and military electronics. But no one had succeeded with it in anything so complicated as a computer. In the computer industry, engineers had developed a saying: "Gallium arsenide is the technology of the future," they would say. "And it always will be."

Second most important superconducting material: applications of superconductivity.

Stable isotope.

Highly radioactive isotope of caesium with half-life of 30.17 y. Produced from the nuclear fission of uranium, TODO exact reaction, not found in nature.

The fucked thing about this byproduct is that it is in the same chemical family as sodium, and therefore forms a salt that looks like regular table salt, and dissolves in water and therefore easily enters your body and sticks to things.

Another problem is that its half-life is long enough that it doesn't lose radioactivity very quickly compared to the life of a human person, although it is short enough to make it highly toxic, making it a terrible pollutant when released.

This is why for example in the goiânia accident a girl ended up ingesting Caesium-137 after eating an egg after touching the Caesium with her hands.

Not "Yt" because that is already "Yttrium". God.

There are no stable isotopes.

The least unstable isotope, occurs as part of the uranium 238 decay chain.

Discovered by Marie Curie when she noticed that there was some yet unknown more radioactive element in their raw samples, after uranium had already been separated.

The uranium 238 decay chain is the main source of naturally occurring radium.

Vs plutonium: uranium vs plutonium Quora answer by Ciro Santilli.