Ice 9 - Astronomy News

Blobrana

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Posts: 131433

Date: Jan 18 00:27 2012

Quantum liquid Ice	Permalink

Scientists predict an out-of-this-world kind of ice Cornell scientists are boldly going where no water molecule has gone before -- that is, when it comes to pressures found nowhere on Earth. Exploring what Cornell's Neil Ashcroft calls the "utterly fundamental" transition from insulating to conducting, or metallic, matter, the researchers have combined high-powered computing and "chemical intuition" to discover new phases of water -- specifically, ice at extremely high pressures nonexistent on Earth but probably abundant elsewhere in the solar system. The research, published online Dec. 29 in Proceedings of the National Academy of Sciences, was conducted by Ashcroft, the Horace White Professor of Physics Emeritus; Roald Hoffmann, the 1981 chemistry Nobel laureate and Frank H.T. Rhodes Professor in Humane Letters Emeritus; and Andreas Hermann, a postdoctoral associate in chemistry and physics. Read more __________________

Blobrana

L

Posts: 131433

Date: Sep 22 01:09 2010

Superionic water	Permalink

What glows yellow and behaves like a liquid and a solid at the same time? Water - at least in the strange form it appears to take deep within Uranus and Neptune. This exotic stuff might help explain why both planets have bizarre magnetic fields. Simulations in 1999 and an experiment in 2005 hinted that water might behave like both a solid and a liquid at very high pressures and temperatures. Under such conditions, the oxygen and hydrogen atoms in the water molecules would become ionised, with the oxygen ions forming a lattice-like crystal structure and the hydrogen ions able to flow through the lattice like a liquid. This "superionic" water, forming at temperatures above 2000 °C or so, should glow yellow. Read more __________________

Blobrana

L

Posts: 131433

Date: Apr 8 12:43 2009

Pentagon-shaped Ice	Permalink

Water usually crystallises as hexagonal rings but scientist at the University of Liverpool have discovered a five-sided ice chain that breaks the usual rules. Researchers, in collaboration with University College London and the Fritz-Haber Institut in Berlin, created the first moments of water condensing on matter - a process vital for the formation of clouds in the atmosphere - by analysing how the two interact on a flat copper surface. Ice has rarely been viewed at the nanoscale before and the team discovered a one-dimensional chain structure built from pentagon-shaped rings, rather than the more commonly seen hexagonal structures of ice formations like those seen in snowflakes. This discovery could lead to scientists developing new materials for seeding clouds and causing rain. Cloud seeding is a form of weather modification, where the amount or type of precipitation that falls from clouds is altered by dispersing substances into the air which modify cloud particles. This process can increase amounts of rain and snow but can also be used to suppress hail and fog. The substances currently used to seed clouds are chosen to bind to hexagonal ice, but this work suggests that the process could work equally well with materials which bind to other structures. Read more __________________

Blobrana

L

Posts: 131433

Date: Sep 24 10:40 2008

High-pressure ice	Permalink

The deep interior of Neptune, Uranus and Earth may contain some solid ice. Through first-principle molecular dynamics simulations, Lawrence Livermore National Laboratory scientists, together with University of California, Davis collaborators, used a two-phase approach to determine the melting temperature of ice VII (a high-pressure phase of ice) in pressures ranging from 100,000 to 500,000 atmospheres. For pressures between 100,000 and 400,000 atmospheres, the team, led by Eric Schwegler, found that ice melts as a molecular solid (similar to how ice melts in a cold drink). But in pressures above 450,000 atmospheres, there is a sharp increase in the slope of the melting curve due to molecular disassociation and proton diffusion in the solid, prior to melting, which is typically referred to as a superionic solid phase. Read more __________________

Blobrana

L

Posts: 131433

Date: Sep 29 07:50 2007

Ht Ice	Permalink

Physicists have shown that specially treated diamond coatings can keep water frozen at body temperature, a finding that may have applications in future medical implants. Researchers spent a year building and examining computer models that showed that a layer of diamond coated with sodium atoms will keep water frozen up to 108 degrees Fahrenheit. In ice, water molecules are arranged in a rigid framework that gives the substance its hardness. The process of melting is somewhat like a building falling down: pieces that had been arranged into a rigid structure move and flow against one another, becoming liquid water. Read more __________________

Blobrana

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Posts: 131433

Date: Jun 21 13:24 2007

The formation of ice	Permalink

Collaborative research between scientists in the UK and Germany (published in this weeks Nature Materials) has led to a breakthrough in the understanding of the formation of ice. Dr Angelos Michaelides of the London Centre for Nanotechnology (formerly of the Fritz-Haber Institut der Max-Planck Gesellschaft in Berlin) and Professor Karina Morgenstern of the Leibniz University Hannover have combined experimental observations with theoretical modelling to reveal with unprecedented resolution the structures of the smallest pieces of ice that form on hydrophobic metal surfaces. The results provide information about the process of ice nucleation at a molecular level and take science a significant step closer to understanding the mysterious process through which ice forms around microscopic dust particles in the upper atmosphere. Because this is the basis of cloud formation, knowing how different particles promote ice formation is crucial for climate change models. Read more __________________

Blobrana

L

Posts: 131433

Date: Apr 29 16:34 2005

Ice 9	Permalink

A new form of ice may exist at high pressures and when temperatures are near absolute zero, between minus 4 to 50 Kelvin, according to researchers at the National Synchrotron Radiation Research Centre. Density functional theory (DFT) calculations under these conditions correctly accounts for the pre-edge feature of ice. However, quite unexpectedly, new data indicates substantial spectral changes from ice IX, suggesting a significant change of the H2O framework in this P-T regime. In short, the exciting prospect of the formation of a possible new ice phase. Read more __________________

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