Ice 19

[Recusant]

If you've read Cat's Cradle by Kurt Vonnegut Jr. you're aware of ice-nine. Scientists have apparently discovered a 19th form of ice crystal.

"Exotic crystals of 'ice 19' discovered" | Live Science

Scientists have identified the 19th form of water ice. The exotic, four-sided crystals of this rare ice variety, now dubbed ice XIX, form at ultra-low temperatures and ultra-high pressures.

It only exists in laboratory experiments, but researchers say it reveals more about other forms of ice, which can be found deep in the Earth's mantle and on very cold planets and moons.

"To name a new ice form, one needs to elucidate exactly what the crystal structure is," said lead researcher Thomas Loerting, a professor of physical chemistry at the University of Innsbruck in Austria. That means figuring out the simplest repeating structure of the crystal, where all of the atoms are located within that structure, and what the symmetry of the crystal structure is, Loerting said.

"Only if all of these are known, you are allowed to name your ice ... Ice XIX is now the name for the new ice phase discovered in our work," he told Live Science in an email.

[. . .]

Almost everyone is familiar with the beautiful six-sided variety of snowflakes, which mirrors the hexagonal arrangement of oxygen atoms in the crystals of water ice that make them.

But regular six-sided crystals of ice — ice I — are actually just one of its many forms, which are known as polymorphs. And until recently, 18 different polymorphs of water ice had been formally identified — although only six-sided ice is common on Earth.Although ice might seem simple, it is complicated stuff. For instance, only the oxygen atoms in the water molecules of six-sided ice crystals form a hexagonal shape, while their hydrogen atoms are randomly oriented around them. This makes ice I a "disordered" or "frustrated" ice in the terminology of ices. One of the properties of such disordered ices is that they can deform under pressure: "This is the reason why glaciers flow," Loerting said.

In contrast, the hydrogen atoms in several of the other polymorphs of ice also have their own crystal patterns, and they are called "hydrogen-ordered" or "H-ordered" as a result. Unlike disordered ices, H-ordered ices are very brittle and will shatter, rather than deform, he said.

In those terms, the newly identified 19th form of ice is an H-ordered ice; in fact, it's an H-ordered form of a disordered ice, called ice VI, which has a random pattern of hydrogen atoms. And ice VI also has yet another H-ordered polymorph, ice XV, in which the hydrogen atoms are aligned in an entirely different pattern.

[Continues . . .]

The paper is open access: "Structural characterization of ice XIX as the second polymorph related to ice VI" | Nature Communications

[Randy]

I would have never thought that there are other types of ice crystals although it makes perfect sense. Good find Recusant!

[Dark Lightning]

That is quite interesting! More Ice-

[hermes2015]

Vonnegut was required reading when I was in my twenties.

[billy rubin]

still should be.

his stuff has a razor edge to it.

[Tank]

Fascinating.

[Icarus]

 crystal structures are fascinating.  So little time, so much to learn.

[hermes2015]

crystal structures are fascinating.  So little time, so much to learn.

And at the atomic level X-ray crystallography is pure magic. The technique vindicated me when I was still a chemist, but that story is for another day.

[Icarus]

Tell us the story Hermes.  You are among interested friends.

[hermes2015]

Tell us the story Hermes.  You are among interested friends.

Ha, I didn't want to bore anyone, Icarus, although that has never stopped me here. When I was doing my Masters degree research, I obtained a curious white crystalline compound, with a high melting point, from one of my reactions. After all the usual structural elucidation steps, I  concluded that it was 9-triptycyl iodoformate, which is triptycene with an iodoformate group at the bridgehead on the 9-position.

triptycene

I reported the result to my professor, who laughed and took a book from his shelf. The book stated that iodoformates were very unstable compounds and that they could not survive after forming. He said that my stable molecule couldn't possibly exist if it were an iodoformate. All my elemental composition, UV spectra, NMR, IR spectra, and other results, led me to believe that it was in fact 9-triptycyl iodoformate. The clincher was X-ray crystallography, which unambiguously proved that I was correct, and had indeed made the first stable iodoformate.

[Tank]

Tell us the story Hermes.  You are among interested friends.

Ha, I didn't want to bore anyone, Icarus, although that has never stopped me here. When I was doing my Masters degree research, I obtained a curious white crystalline compound, with a high melting point, from one of my reactions. After all the usual structural elucidation steps, I  concluded that it was 9-triptycyl iodoformate, which is triptycene with an iodoformate group at the bridgehead on the 9-position.

triptycene

I reported the result to my professor, who laughed and took a book from his shelf. The book stated that iodoformates were very unstable compounds and that they could not survive after forming. He said that my stable molecule couldn't possibly exist if it were an iodoformate. All my elemental composition, UV spectra, NMR, IR spectra, and other results, led me to believe that it was in fact 9-triptycyl iodoformate. The clincher was X-ray crystallography, which unambiguously proved that I was correct, and had indeed made the first stable iodoformate.

Did you tell your professor 

[hermes2015]

Tell us the story Hermes.  You are among interested friends.

Ha, I didn't want to bore anyone, Icarus, although that has never stopped me here. When I was doing my Masters degree research, I obtained a curious white crystalline compound, with a high melting point, from one of my reactions. After all the usual structural elucidation steps, I  concluded that it was 9-triptycyl iodoformate, which is triptycene with an iodoformate group at the bridgehead on the 9-position.

triptycene

I reported the result to my professor, who laughed and took a book from his shelf. The book stated that iodoformates were very unstable compounds and that they could not survive after forming. He said that my stable molecule couldn't possibly exist if it were an iodoformate. All my elemental composition, UV spectra, NMR, IR spectra, and other results, led me to believe that it was in fact 9-triptycyl iodoformate. The clincher was X-ray crystallography, which unambiguously proved that I was correct, and had indeed made the first stable iodoformate.

Did you tell your professor 

Yes, of course! I made sure to rub it in. He was actually very pleased; I was his student, after all.

[Recusant]

Hypothesizing that part of the interior of gas giant planets is ice 19, and may be involved in producing the unusual magnetic fields around such planets. It is unclear to me whether this latest paper is making a claim to have produced a different ice phase which it's calling ice 19, or is merely building on and possibly confirming the findings of the earlier paper.

"Strange Form of Ice Found That Only Melts at Extremely Hot Temperatures" | Science Alert

Odd things happen inside planets, where familiar materials are subjected to extreme pressures and heat.

Iron atoms probably dance within Earth's solid inner core, and hot, black, heavy ice – that's both solid and liquid at the same time – likely forms within the water-rich gas giants, Uranus and Neptune.

Five years ago, scientists recreated this exotic ice, called superionic ice, for the first time in lab experiments; and four years ago they confirmed its existence and crystalline structure.

Then just last year, researchers at several universities in the United States and the Stanford Linear Accelerator Center laboratory in California (SLAC) discovered a new phase of superionic ice.

Their discovery deepens our understanding as to why Uranus and Neptune have such off-kilter magnetic fields with multiple poles.

[Continues . . .]

The paper is open access.

"Dynamic compression of water to conditions in ice giant interiors" | Nature Scientific Reports

Abstract:

Recent discoveries of water-rich Neptune-like exoplanets require a more detailed understanding of the phase diagram of H2O at pressure–temperature conditions relevant to their planetary interiors. The unusual non-dipolar magnetic fields of ice giant planets, produced by convecting liquid ionic water, are influenced by exotic high-pressure states of H2O—yet the structure of ice in this state is challenging to determine experimentally.

Here we present X-ray diffraction evidence of a body-centered cubic (BCC) structured H2O ice at 200 GPa and ~ 5000 K, deemed ice XIX, using the X-ray Free Electron Laser of the Linac Coherent Light Source to probe the structure of the oxygen sub-lattice during dynamic compression.

Although several cubic or orthorhombic structures have been predicted to be the stable structure at these conditions, we show this BCC ice phase is stable to multi-Mbar pressures and temperatures near the melt boundary. This suggests variable and increased electrical conductivity to greater depths in ice giant planets that may promote the generation of multipolar magnetic fields.

[Recusant]

Will just stick with this thread for the various exotic ices.

Listening to the most recently released episode of The Infinite Monkey Cage in podcast form ("Adventures on Ice") I was surprised to hear the statement that there are 20 known phases. I looked and didn't find much about ice XX (one of the articles) though according to Wikipedia there are now 21 observed phases. Apparently a fast-moving field these days.

In the programme a guest scientist (who has discovered three phases himself) mentioned that according to one hypothesis there are possibly around 19,000 phases, so this thread could go on for some time. 

Not sure if I've noted The Infinite Monkey Cage in the podcast thread, but it's not bad for a comedy/science listen. A half-hour, so not a huge investment.

Onward, with a plastic variant phase of ice VII.  Little did I know when I read that Vonnegut story ages ago that in due time I'd be following the scientific exploration of actual exotic ices. 

"Weird Ice That Could Form on Alien Planets Observed For First Time" | Science Alert

Previously predicted by theoretical models, we now have the first experimental observation of plastic Ice VII. That might sound like a low-budget franchise movie, but it's actually an exotic phase of water that scientists think could form in oceans on alien planets.

How exotic are we talking? Well, plastic Ice VII needs incredibly high temperatures and pressures to form. As temperatures and pressures rise, water molecules are forced into a variety of configurations and dynamics.

An international team of researchers created Ice VII by squeezing water up to pressures of 6 gigapascal and heating it to temperatures as high as 327 °C (620 °F), using high-caliber instruments at the Institut Laue-Langevin (ILL) in France to watch closely as it changed phase.

[Continues . . .]

The paper is behind a paywall.

Abstract:

Water is the third most abundant molecule in the universe and a key component in the interiors of icy moons, giant planets, and Uranus- and Neptune-like exoplanets. Owing to its distinct molecular structure and flexible hydrogen bonds that readily adapt to a wide range of pressures and temperatures, water forms numerous crystalline and amorphous phases.

Most relevant for the high pressures and temperatures of planetary interiors is ice VII, and simulations have identified along its melting curve the existence of a so-called plastic phase where individual molecules occupy fixed positions as in a solid yet are able to rotate as in a liquid. Such plastic ice has not yet been directly observed in experiments.

Here, we present quasi-elastic neutron scattering (QENS) measurements, conducted at temperatures between 450 and 600 K and pressures up to 6 GPa, that reveal the existence of a body centered cubic (bcc) structure, as found in ice VII, with water molecules exhibiting picosecond rotational dynamics typical for liquid water.

Comparison with molecular dynamics simulations indicates that this plastic ice VII does not conform to a free rotor phase but rather exhibits rapid orientational jumps, as observed in jump-rotor plastic crystals. We anticipate that our observation of plastic ice VII will impact our understanding of the geodynamics of icy planets and the differentiation processes of large icy moons.