I’ve been reading a bit about ice crystals at higher pressures, with more complex crystalline structures than Ice I (normal ice). The websites I’ve seen have lots of nifty graphics showing how these molecules arrange themselves, but nothing at the “macro” level.
If someone were to create a large quantity (say, a cubic foot) of complex ice, how would it look and feel? Would a more complex molecular structure make it distinguishable from regular ice? Or would it just explode at sea-level pressure?
Good question. I’ll point out that the twophases of solid carbon have radically different appearances and mechanical properties, so it’s not out of the realm of possibility that Ices II-XV would have different appearances and feels as well.
A bit of Googling pulled up this paper with theoretical calculations on the optical properties of Ices X, XI, and XV. Most of the interesting results are contained in the graphs at the end. Of note:
[ul][li]Figure 5: The absorption coefficients for all three phases are essentially zero below about 10 eV. Since the visible range of light tops out at about 3 eV, this means that a perfect crystal of these ices would not appear to have any color. (I think.)[/li][li]Figure 9: The refractive index for Ices X and XV are about 2 in the visible range, while that of Ice XI is about 1.4. This is to be compared with the refractive index for normal ice, which is about 1.3. This difference (for Ices X and XV) might be visually noticeable; the ice might appear to “sparkle” more as it bends light from unexpected directions. (Of course, the shape of the crystal itself greatly affects this as well.)[/li][*]Figure 10: Ices XI and XV are anisotropic, meaning that a single crystal of either would exhibit birefringence. If you looked through them at an angle, you would see multiple images of an object behind them.[/ul]The chromatic dispersion of these crystals (i.e., how much they “split” the spectrum via refraction, as a prism does) isn’t discussed in the paper, but I would expect that these properties would be somewhat different as well.
I don’t know if this helps, but I’ll point out that iron and steel have many different phases, each with different properties. But they all look pretty much the same to the naked eye. Maybe slightly different colors, but that’s about it.
Do these different phases of ice have any applicability in a practical sense? Such as, eg for the sake of silliness, a better highball? Or as precursors in some chemical or physical process?
Well, Ice-XI is the only “exotic” phase of ice that can exists at atmospheric pressure; you just need to get the water down to about -200 C (-330 F) to create it. So a cube of Ice-XI would cool your highball off fairly effectively.
Right, but we’re talking about pressures measured in megapascals… pressures thousands of times greater than normal Earth atmosphere. (Sea level pressure is about 100 kilopascals. Ice III, for example, forms at 300 megapascals and -10 degrees farenheit.)
By the way, the answer to they last question (except maybe for ice XI) is “Yes”. You’d need to look at through the wall of a (very, very) high pressure vessel.
Abstract
Water-rich regions in Earth’s deeper mantle are suspected to play a key role in the global water budget and the mobility of heat-generating elements. We show that ice-VII occurs as inclusions in natural diamond and serves as an indicator for such water-rich regions. Ice-VII, the residue of aqueous fluid present during growth of diamond, crystallizes upon ascent of the host diamonds but remains at pressures as high as 24 gigapascals; it is now recognized as a mineral by the International Mineralogical Association. In particular, ice-VII in diamonds points toward fluid-rich locations in the upper transition zone and around the 660-kilometer boundary.
Newspaper account.
ETA: 1) reason they call that stuff ice. 2) Somewhere theres a thread in GQ, if not elsewhere, on the Man of Steel making diamonds from coal and the strength and circs required. Does this add anything to that ever-rich topic?
If the Ice-XI is returned to a more reasonable out of the home freezer temperature of say -10C will it change back to normal ice? Diamonds don’t change back to graphite or something else when exposed to more human friendly temperatures.