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Titolo:
Thermal properties of metastable ice XII
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:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 51, volume: 104, anno: 2000,
pagine: 12102 - 12104
SICI:
1520-6106(200012)104:51<12102:TPOMIX>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
DENSITY AMORPHOUS WATER; LIQUID WATER; LOW-TEMPERATURE; CUBIC ICE; X-RAY; TRANSITION; DIFFRACTION; PRESSURE; PHASES;
Tipo documento:
Letter
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
22
Recensione:
Indirizzi per estratti:
Indirizzo: Hallbrucker, A Innsbruck Univ, Inst Allgemeine Anorgan & Theoret Chem, Anichstr 35, A-6020 Innsbruck, Austria Innsbruck Univ Anichstr 35 Innsbruck Austria A-6020 ustria
Citazione:
I. Kohl et al., "Thermal properties of metastable ice XII", J PHYS CH B, 104(51), 2000, pp. 12102-12104

Abstract

Samples of ice XII containing varying amounts of high-density amorphous water (HDA) were prepared by pressurizing hexagonal ice up to 1.8 GPa at 77 K, and they were characterized by X-ray diffraction and differential scanning calorimetry (DSC). Only exotherms were observed in the DSC curves on heating at a rate of 10 K min(-1) up to the melting point: conversion of HDA tolow-density amorphous water (LDA) at 124 K, LDA-->cubic ice transition at 166 K, and at 155 K from ice XII to cubic ice. Thus, unlike ice VIII, ice XII converts directly into cubic ice, and not via LDA. The enthalpy of the ice XII-->cubic ice transition is -1.27 +/- 0.05 kJ mol(-1). From comparisonwith the reported enthalpy value of the ice V-->cubic ice transition of -0.915 kJ mol(-1) determined at similar temperature (Handa, Y. P.; Klug, D. D.; Whalley, E. Can. J. Chem. 1988, 66, 919), we conclude that ice XII is metastable with respect to ice V in the investigated temperature range.

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Documento generato il 05/12/20 alle ore 14:16:33