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Titolo:
Ice XII forms on compression of hexagonal ice at 77 K via high-density amorphous water
Autore:
Kohl, I; Mayer, E; Hallbrucker, A;
Indirizzi:
Innsbruck Univ, Inst Allgemeine Anorgan & Theoret Chem, A-6020 Innsbruck, Austria Innsbruck Univ Innsbruck Austria A-6020 Chem, A-6020 Innsbruck, Austria
Titolo Testata:
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
fascicolo: 4, volume: 3, anno: 2001,
pagine: 602 - 605
SICI:
1463-9076(2001)3:4<602:IXFOCO>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
PRESSURE-INDUCED AMORPHIZATION; LOW-TEMPERATURE; 1ST-ORDER TRANSITION; X-RAY; TRANSFORMATIONS; DIFFRACTION; LIQUID; PHASE; VIII;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Kohl, I Innsbruck Univ, Inst Allgemeine Anorgan & Theoret Chem, A-6020 Innsbruck, Austria Innsbruck Univ Innsbruck Austria A-6020 -6020 Innsbruck, Austria
Citazione:
I. Kohl et al., "Ice XII forms on compression of hexagonal ice at 77 K via high-density amorphous water", PHYS CHEM P, 3(4), 2001, pp. 602-605

Abstract

Samples of high-density amorphous water (HDA) were prepared by compressionof hexagonal ice (ice Ih) in a piston-cylinder apparatus at 77 K up to 1.8GPa, recovered at ambient pressure under liquid N-2 and characterized by X-ray diffraction and differential scanning calorimetry. Thereafter HDA samples were reloaded into the piston-cylinder apparatus, compressed at 77 K upto 1.8 GPa, recovered under liquid N-2 and characterized. Formation of iceXII on compression of HDA was observed only when a sudden pronounced pressure drop occurred at pressures greater than or similar to1.1 GPa. Pressure drops below this threshold value, or occurring during the initial compression of ice Ih, did not induce formation of ice XII. Pressure-displacement curves obtained on compression of ice Ih are consistent with formation of iceXII from HDA, and not from ice Ih. We propose that shock waves generated by the pressure drops cause transient local heating up to the temperature range of the ice V domain, and that this induces nucleation and crystal growth of ice XII. The threshold value of approximate to 1.1 GPa pressure necessary for the HDA --> ice XII transition indicates that the density of HDA has to reach a certain minimal value before conversion into ice XII becomes possible. Ice XII could thus be formed via HDA by meteorite impact on the surfaces of icy satellites of the outer planets whenever the temperatures arelow.

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Documento generato il 28/09/20 alle ore 01:21:28