title: 89Y magic-angle spinning NMR of Y2Ti2-xSnxO7 pyrochlores.
abstract: The yttrium local environment in the series of pyrochlores Y2Ti2-xSnxO7 was studied using 89Y NMR. Oxides with the pyrochlore structure exhibit a range of interesting physical and chemical properties, resulting in many technological applications, including the encapsulation of lanthanide- and actinide-bearing radioactive waste. The use of the nonradioactive Y3+ cation provides a sensitive probe for any changes in the local structure and ordering with solid solution composition, through 89Y (I = 1/2) NMR. We confirm that a single pyrochlore phase is formed over the entire compositional range, with Y found only on the eight-coordinated A site. A significant (approximately 15 ppm) chemical shift is observed for each Sn substituted into the Y second neighbor coordination environment. The spectral signal intensities of the possible combinations of Sn/Ti neighbors match those predicted statistically assuming a random distribution of Sn4+/Ti4+ on the six-coordinated pyrochlore B site.
authors.affiliation: School of Chemistry and EaStCHEM, University of St. Andrews, North Haugh, St. Andrews KY16 9ST, UK. sema@st-andrews.ac.uk
authors.forename: Sharon E
authors.initials: SE
authors.lastname: Ashbrook
authors.forename: Karl R
authors.initials: KR
authors.lastname: Whittle
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Lumpkin
authors.forename: Ian
authors.initials: I
authors.lastname: Farnan