Objetivo
The structure and dynamics of ice phases as well as of water are studied by novel neutron scattering techniques under pressure. Despite the omnipresence of water in nature, many fundamental questions remain unanswered, which are currently subject of vivid scientific interest. These include:
(i) the mechanisms responsible for the anomalous thermodynamic properties of liquid and amorphous water and consequently the validity of proposed theoretical models,
(ii) the lattice dynamics (phonon dispersions) of various ice phases under pressure, in particular ice lh, and
(iii) the precise crystal structure of disordered ice VII and generally all other ice phases.
With hydrogen bonds responsible for the observed phenomena, neutrons represent one of the most powerful probes to tackle the above questions. The Paris-Edinburgh pressure cell allows for high-pressure neutron scattering studies up to 30 GPa.
Extensions of this cell for the study of liquids or single crystals at elevated temperatures are now available or in development. Here we propose neutron scattering studies on fundamental issues of current interest, i.e.
(i) on liquid water at 5-8 GPa and 500AC (beyond the current limit of standard high pressure diffraction techniques),
(ii) on the amorphous forms of ice and
(iii) on single crystals of the ice VII phase above 2 GPa at 82A, as well as
(iv) inelastic neutron scattering studies on the ordinary ice phase lh at elevated pressure.
The study of water may have direct relevance to other research areas, as biophysics/chemistry, geo- and astrophysics (detailed knowledge about the structure and thermodynamics of H-bonded systems). Conceptually new issues observed in water were found to have analogues in other fields of physics and may find applications in novel materials (crystal-amorphous, amorphous-amorphous and liquid-liquid phase transitions). Novel high-pressure techniques developed in course of this project may find broader application in the research with neutrons.
Ámbito científico
Palabras clave
Convocatoria de propuestas
FP6-2002-MOBILITY-7
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