title: A molecular dynamics simulation interpretation of neutron and x-ray diffraction measurements on single phase Y(2)O(3)-Al(2)O(3) glasses.
abstract: Molecular dynamics simulations and complementary neutron and x-ray diffraction studies have been carried out within the single phase glass forming range of (Y(2)O(3))(x)(Al(2)O(3))((100-x)), for x = 27 and 30. For x = 27, the experimental Al-O and Y-O coordination numbers are found to be 4.9 ± 0.2 and 6.9 ± 0.4 respectively, compared to 4.4 and 6.8 obtained from the simulation. Similar results were found for x = 30. An R-factor analysis showed that the simulation models agreed to within ∼6% of the diffraction data in both cases. The Al-O polyhedra are dominated by fourfold and fivefold species and the Y-O local coordinations are dominated by sixfold, sevenfold and eightfold polyhedra. Analysis of the oxygen environments reveals a large number of combinations, which explains the high entropy of single phase yttrium aluminate glasses and melts. Of these, the largest variation between x = 27 and 30 is found in the number of aluminum oxygen triclusters (oxygens bonded to three Al) and oxygens surrounded by three Y and a single Al. The most abundant connections are between the AlO(x) and YO(y) polyhedra of which 30% are edge shared. The majority of AlO(x)-AlO(x) connections were found to be corner shared.
authors.affiliation: Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203, USA.
authors.forename: Jincheng
authors.initials: J
authors.lastname: Du
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Benmore
authors.forename: Rene
authors.initials: R
authors.lastname: Corrales
authors.forename: Robert T
authors.initials: RT
authors.lastname: Hart
authors.forename: J K Richard
authors.initials: JK
authors.lastname: Weber