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dc.contributor.advisorSow-Hsin Chen.en_US
dc.contributor.authorZhang, Yangen_US
dc.contributor.otherMassachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.en_US
dc.date.accessioned2013-01-23T20:23:15Z
dc.date.available2013-01-23T20:23:15Z
dc.date.copyright2010en_US
dc.date.issued2010en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/76568
dc.descriptionThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2010.en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references (p. 91-104) and index.en_US
dc.description.abstractWater is the most ubiquitous substance on earth, and is essential to sustain all known forms of life. However, despite centuries of research, a coherent picture of the unusual phase behavior of water is so far lacking. The most promising theory under scrutiny relies on the hypothetical existence of a liquid-liquid phase transition and an associated liquid-liquid critical point hidden in the region of supercooled temperatures and elevated pressures, where bulk water does not exist in liquid state. Therefore it is a grand experimental challenge to investigate the properties of water, both thermodynamic and dynamic, in the relative region of the phase diagram. A combination of neutron triple-axis spectrometer and small-angle neutron scattering instrument are used to measure the density of water confined in a nanoporous silica matrix MCM-41-S in a Temperature-Pressure range inaccessible for the bulk (300-130 K and 1-2900 bar), namely, the equation of state p(T, P). The measured isobaric density profiles clearly show a change of behavior around 1500 bar. This experiment provides the most direct evidence supporting the existence of a liquid-liquid critical point in such confined water. The experimental result further implies that the nature of the liquid-liquid critical point of water might be of a tricritical type. Moreover, the reported density data of confined water under extreme conditions are valuable for the vast communities in biological, geological and planetary sciences. Parallel to the density measurement, the dynamics of water in confined geometry, such as aged cement paste and the vicinity of protein surfaces, are also investigated using a variety of quasi-elastic and inelastic neutron scattering spectrometers. A wide range of pre-glass-transition phenomena, such as dynamic crossover, dynamic heterogeneity and boson peak, are observed above the conventional glass-transition temperature. Possible explanations are discussed in the frameworks of the liquidliquid critical point scenario of water and the extended mode-coupling theory. Computer simulations are frequently exploited to achieve a unified interpretation. These new findings of confined water may provide new insights to the research on glassy systems of multi-scales as well as innumerable examples in soft condensed matters, where randomness and cooperativity are common and intrinsic.en_US
dc.description.statementofresponsibilityby Yang Zhang.en_US
dc.format.extent105 p.en_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectNuclear Science and Engineering.en_US
dc.titleNeutron scattering investigations on the unusual phase behavior of wateren_US
dc.typeThesisen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Nuclear Science and Engineering
dc.identifier.oclc823510482en_US


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