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Researchers from Argonne and Oak Ridge national laboratories discovered new forms of ice. Clockwise from lower left are Chris Tulk, Jacob Urquidi, Jorg Neuefeind and Chris Benmore. |
New ice forms reshape ice research world |
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New forms of ice, once deemed impossible by popular water theories, have been discovered by Argonne researchers and their Canadian colleagues. High-density and low-density amorphous, or non-crystalline, ice are among the more than one dozen known ice forms. Many scientists believe that these two ice forms are the low-temperature manifestations of two different states of liquid water, and that the transition between the two forms is sudden; that is, their density is discontinuous. But Argonne researcher Chris Benmore, Oak Ridge researcher Chris Tulk and their colleagues at Argonne, the University of Guelph and the National Research Council of Canada, have found at least three amorphous states of ice that exist between the high- and low-density forms. Results were reported in Science. “These data may well call into question several of the widely held modern structural and thermodynamic theories of liquid water,” said Tulk about this discovery. The researchers discovered these new ice forms while conducting lengthy experiments with the high-density form of amorphous ice supplied by the National Research Council in Ottawa, Canada. This form, made by squeezing “regular freezer” ice to 13,000 times atmospheric pressure in liquid nitrogen, does not occur naturally on Earth but can exist in the colder regions of space. While measuring this high-density form of ice over a period of days, the researchers observed a change into new ice forms. “We are the first people to discover and measure the structures of these new ice forms,” said Benmore. “Our results have a significant effect on understanding the many different states of water and ice and make it difficult to believe that a second critical point really exists in water—a widely accepted notion. It may have practical implications in other fields such as cryo-preservation of biomolecules.” Researchers conducted neutron diffraction studies on the high-density amorphous ice samples at Argonne’s Intense Pulsed Neutron Source (IPNS). Coupled with X-ray diffraction studies using the BESSRC-CAT at Argonne’s Advanced Photon Source (APS), the researchers were able to learn more about the new ice forms. “It was the reliability of the IPNS and intensity of the APS that really helped us closely monitor and characterize the formation of these new ices in real time,” said Benmore. For more information, please contact David Jacqué. |