Tuesday, October 21, 2008

Ice IX

This afternoon, I stumbled upon this phase diagram of water, showing the different phases of ice. Depending on temperature and pressure, solid water can have a large variety of crystal structures.

I couldn't avoid having a closer look: Ice-Nine exists!

from Landolt-Börnstein: "Physical properties of ice"
(DOI: 10.1007/10201909_90 - free PDF preview)

Fortunately, unlike its mythical cousin, the real Ice-Nine (labelled "IX" in the lower left corner of the diagram) cannot occur at ambient conditions, but exists as a metastable phase only below about -100 centigrade (170 K), and at pressures of a few kbar.

So, no danger that it may accidentally solidify all liquid water...


  1. If I recall Cat's Cradle correctly, the destruction of the world was not "accidental". The creator of ice nine knew exactly what he was doing.

  2. Since his brother was an expert on ice, I think Vonnegut also Knew what he was doing.

  3. Hi Stefan,

    Thanks for the insight as I’ve always found it fascinating how solids are often more complicated then first considered with not only having one temperature defining them. The one that fascinates me personally the most is carbon, which many consider as being simply a lump of coal yet is found in forms so diverse in qualities ranging being naturally the hardest substance as with diamond or so soft as with soot and still other forms so strong being the extended Fullerenes recently discovered. With all those types of solid water you’ve pointed to I also wonder how many when actually first observed would present themselves as initially recognizable for what they are?



  4. Bee - been away a few so missed this.. Did you catch the Physics World from this past winter with the article on snowflakes? I've actually got the book by the same author (no shock there!). Snowflakes are really amazing.

  5. Hi Snowboarder,

    Nice to see you around. We had the first snow today, how is it in Vermont? No, I didn't read the article, but come to think of it last year's Physics Today issues are probably somewhere in the pile on my desk. Best,



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