X-ray and neutron diffraction studies and MD simulation of atomic configurations in polyamorphic Y2O3-Al2O3 systems

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dc.contributor.author Wilding, Martin C.
dc.contributor.author Wilson, Myra Scott
dc.contributor.author McMillan, Paul F.
dc.date.accessioned 2010-01-21T11:06:00Z
dc.date.available 2010-01-21T11:06:00Z
dc.date.issued 2005-02-15
dc.identifier.citation Wilding , M C , Wilson , M S & McMillan , P F 2005 , ' X-ray and neutron diffraction studies and MD simulation of atomic configurations in polyamorphic Y2O3-Al2O3 systems ' Philosophical Transactions A: Mathematical, Physical and Engineering Sciences , vol 363 , no. 1827 , pp. 589-607 . en
dc.identifier.issn 1471-2962
dc.identifier.other PURE: 143810
dc.identifier.other dspace: 2160/4015
dc.identifier.uri http://hdl.handle.net/2160/4015
dc.description Wilding, M. C., Wilson, M., McMillan, P. F. (2005). X-ray and neutron diffraction studies and MD simulation of atomic configurations in polyamorphic Y2O3-Al2O3 systems. Philosophical Transactions of The Royal Society A Mathematical, Physical & Engineering Sciences, 363 (1827), 589-607. en
dc.description.abstract Supercooled liquids in the Y2O3-Al2O3 system undergo a liquid–liquid phase transition between a high–temperature, high–density amorphous (HDA) polymorph form and one with lower density (LDA form) that is stable at lower temperature. The two amorphous polymorphs have the same chemical composition, but they differ in their density (ca. 4% difference) and in their heat content (enthalpy) and entropy determined by calorimetry. Here we present new results of structural studies using neutron and high–energy X–ray diffraction to study the structural differences between HDA and LDA polyamorphs. The combined datasets show no large differences in the average nearest–neighbour Al−O or Y−O bond lengths or coordination numbers between the low– and high–density liquids. However, the data indicate that substantial changes occur among the packing geometries and clustering of the Al−O and Y−O coordination polyhedra, i.e. within the second–nearest–neighbour shell defined by the metal–metal (i.e. Y−Y, Y−Al, Al−Al) interactions. Polarizable ion model molecular dynamics simulations of Y2O3−Al2O3 liquids are used to help interpret the pair–correlation functions obtained from X–ray and neutron scattering data. Unexpectedly large density fluctuations are observed to occur during the simulation of nominally equilibrated systems. These are interpreted as being due to dynamic sampling of high– and low–density configurations within the single–phase liquid at temperatures above the critical point or phase transition line. Calculated partial radial distribution functions indicate that the primary differences between HDA and LDA configurations occur among the Y−Y correlations. en
dc.format.extent 19 en
dc.language.iso eng
dc.relation.ispartof Philosophical Transactions A: Mathematical, Physical and Engineering Sciences en
dc.subject polyamorphism en
dc.subject liquid-liquid transition en
dc.subject rare earth aluminates en
dc.subject amorphous diffraction en
dc.subject x-ray and nuetron scattering en
dc.subject MD simulation en
dc.title X-ray and neutron diffraction studies and MD simulation of atomic configurations in polyamorphic Y2O3-Al2O3 systems en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.identifier.doi http://dx.doi.org/10.1098/rsta.2004.1510
dc.contributor.institution Materials Research en
dc.contributor.institution Institute of Mathematics & Physics (ADT) en
dc.contributor.institution Department of Computer Science en
dc.description.status Peer reviewed en


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