Room Temperature Superconductor Material

Wow! As soon as they fix that 39 million psi problem, I want some!

Simple density problem, should work that out with molecular matching or spin or something...somebody will stumble across the answer someday...

I guess the high pressure is necessary to get the hydrogen dense enough to form a metallic superconducting lattice.

"Researchers have spent decades searching for a superconductor whose Cooper pairs tango tightly enough to withstand the heat of everyday environments. In 1968, Neil Ashcroft, a solid-state physicist at Cornell University, proposed that a lattice of hydrogen atoms would do the trick. Hydrogen’s diminutive size lets electrons get closer to the nodes of the lattice, augmenting their interactions with the vibrations. Hydrogen’s lightness also allows those guiding ripples to vibrate faster, further strengthening the glue that binds the Cooper pairs.

Impractically high pressures are needed to squash hydrogen into a metallic lattice. Still, Ashcroft’s work raised hopes that some “hydride”— a mixture of hydrogen and a second element — might deliver metallic hydrogen’s superconductivity at more accessible pressures."

https://www.quantamagazine.org/physicists-discover-first-room-temperature-superconductor-20201014/

The illustration in your really interesting link looks like a cellphone held between two vey large glass anvils.

I've never seen even an image or diagram of the diamond anvils they actually use, but I imagine that they would have to be formed into a male and female matching pair, something like a very miniature hydraulic piston and chamber. Otherwise, I'd think the material being compressed would simply squish out the sides.

I doubt if these diamond anvils have any facets.

Actually, it looks like they do have some facets and are transparent for viewing the sample with visible light as well as xrays. A gasket keeps the sample from squishing out. I'm impressed -- I have a hard time fixing a faucet without it leaking...

The Diamond Anvil Cell (DAC) was developed at the National Bureau of Standards (NBS). A lot of the diamonds were confiscated illegal diamonds.

From Wiki:

"Components[edit]

There are many different DAC designs but all have four main components:

Force-generating device[edit]

Relies on the operation of either a lever arm, tightening screws, or pneumatic or hydraulic pressure applied to a membrane. In all cases the force is uniaxial and is applied to the tables (bases) of the two anvils.

Two opposing diamond anvils[edit]

Made of high gem quality, flawless diamonds, usually with 16 facets, they typically weigh ​¹⁄₈ to ​¹⁄₃ carat (25 to 70 mg). The culet (tip) is ground and polished to a hexadecagonal surface parallel to the table. The culets of the two diamonds face one another, and must be perfectly parallel in order to produce uniform pressure and to prevent dangerous strains. Specially selected anvils are required for specific measurements – for example, low diamond absorption and luminescence is required in corresponding experiments.

Gasket[edit]

A gasket used in a diamond anvil cell experiment is a thin metal foil, typically 0.3 mm in thickness, which is placed in between the diamonds. Desirable materials for gaskets are strong, stiff metals such as rhenium or tungsten. Steel is frequently used as a cheaper alternative for low pressure experiments. The above-mentioned materials cannot be used in radial geometries where the x-ray beam must pass through the gasket. Since they are not transparent to X-rays, if X-ray illumination through the gasket is required, lighter materials such as beryllium, boron nitride,^[16] boron^[17] or diamond^[18] are used as a gasket. Gaskets are preindented by the diamonds and a hole is drilled in the center of the indentation to create the sample chamber.

Pressure-transmitting medium[edit]

The pressure transmitting medium is the compressible fluid that fills the sample chamber and transmits the applied force to the sample. Hydrostatic pressure is preferred for high-pressure experiments because variation in strain throughout the sample can lead to distorted observations of different behaviors. In some experiments stress and strain relationships are investigated and the effects of non-hydrostatic forces are desired. A good pressure medium will remain a soft, compressible fluid to high pressure.

Pressure-transmitting medium

https://en.wikipedia.org/wiki/Diamond_anvil_cell

Thanks. I know very little about the properties of bulk solid shapes, but after thinking about it, I do know that ridged corners are stiffer than smooth curved surfaces, at least in sheet fabrications, so facets make sense.

My biggest surprise in reading your posted material is the use of a pressure-transmitting fluid surrounding the sample, especially when that fluid is a gas. I had assumed there was nothing but the sample being compressed.

It seems to me that it must be somewhat difficult to determine how much of the compressive force is compressing the sample and how much of it is compressing the gasket. Testing an identical gasket with no sample or pressure-transmitting fluid would give an approximation.

The fluid converts the uniaxial force to pure compression, the same as in a hydraulic system, P = F/A, where A is the area of the diamond anvil face.

It seems to me that it must be somewhat difficult to determine how much of the compressive force is compressing the sample and how much of it is compressing the gasket.

That's true, either a salt (NaCl) crystal or a Ruby crystal is included in the cell for calibration.

"Measuring pressure[edit]

The two main pressure scales used in static high-pressure experiments are X-ray diffraction of a material with a known equation of state and measuring the shift in ruby fluorescence lines. The first began with NaCl, for which the compressibility has been determined by first principles in 1968. The major pitfall of this method of measuring pressure is that you need X-rays. Many experiments do not require X-rays and this presents a major inconvenience to conduct both the intended experiment and a diffraction experiment. In 1971, the NBS high pressure group was set in pursuit of a spectroscopic method for determining pressure. It was found that the wavelength of ruby fluorescence emissions change with pressure, this was easily calibrated against the NaCl scale.^[19][20]"

https://en.wikipedia.org/wiki/Diamond_anvil_cell

"...where A is the area of the diamond anvil face."

or the area of the hole in the gasket, and F must be diminished by the force deforming the gasket.

But since you've pointed out that they are able to determine the pressure optically, thos become moot points. Thanks again!

The diamonds supposedly cost $3k, and their yearly diamond budget is $50k....they break a lot I guess...I suppose they use the diamond dust for drills eh....

$50k/$3k is only 16 or 17 sets. That's only replacing them once every three weeks or so. That sounds quite reasonable to me.

Well that took some time but viola! Give it another 40 years and we might make something useful out of it. (probably wont take that long this tech is in demand.)

Oh, wow. This is good news. We may yet see a room temperature Josephson junction voltage standard replacement.

https://www.sculpteo.com/blog/2017/12/13/top-7-of-the-best-molecular-modeling-software-for-chemistry/