Near-edge X-ray absorption fine structure study of disordering in Gd2(Ti1-yZry)2O7 pyrochlores.
Disorder in Gd2(Ti(1-y)Zry)2O7 pyrochlores, for y = 0.0-1.0, is investigated by Ti 2p and O 1s near-edge X-ray absorption fine structure spectroscopy. Ti(4+) ions are found to occupy octahedral sites in Gd2Ti2O7 with a tetragonal distortion induced by vacant oxygen sites. As Zr substitutes for Ti, the tetragonal distortion decreases, and Zr coordination increases from 6 to 8. The migration of oxygen ions from 48f or 8b sites to vacant 8a sites compensate for the increased Zr coordination, thereby reducing the number of vacant 8a sites, which further reduces the tetragonal distortion and introduces more disorder around Ti. This is evidence for simultaneous cation disorder with anion migration.
Nachimuthu
Ponnusamy
P
Department of Chemistry, University of Nevada, Las Vegas, NV 89154, USA. PNachimuthu@lbl.gov
Thevuthasan
Suntharampillai
S
Adams
Evan M
EM
Weber
William J
WJ
Begg
Bruce D
BD
Mun
Bongjin S
BS
Shuh
David K
DK
Lindle
Dennis W
DW
Gullikson
Eric M
EM
Perera
Rupert C C
RC