Near-Edge X-ray Absorption Fine Structure Study of Ion-beam-induced Phase Transformation in Gd2(Ti1-yZry)2O7

Authors

Ponnusamy Nachimuthu, University of Nevada, Las VegasFollow
S. Thevuthasan, Pacific Northwest National LaboratoryFollow
V. Shutthanandan, Pacific Northwest National LaboratoryFollow
E. M. Adams, Pacific Northwest National LaboratoryFollow
W. J. Weber, Pacific Northwest National Laboratory
B. D. Begg, Australian Nuclear Science and Technology Organization
D. K. Shuh, Lawrence Berkeley National LaboratoryFollow
Dennis W. Lindle, University of Nevada, Las VegasFollow
Eric M. Gullikson, Lawrence Berkeley National LaboratoryFollow
Rupert C. Perera, Lawrence Berkeley National LaboratoryFollow

Document Type

Article

Publication Date

2005

Publication Title

Journal of Applied Physics

Volume

97

Issue

033518

First page number:

6

Abstract

The structural and electronic properties of Gd₂(Ti_1−yZr_y)₂O₇ (y=0–1) pyrochlores following a 2.0-MeV Au²⁺ ion-beam irradiation (~5.0 X 10¹⁴ Au²⁺/cm²) have been investigated by Ti 2p and O 1s near-edge x-ray absorption fine structure (NEXAFS). The irradiation of Gd₂(Ti_1−yZr_y)₂O₇ leads to the phase transformation from the ordered pyrochlore structure (Fd3m) to the defect fluorite structure (Fm3m) regardless of Zr concentration. Irradiated Gd₂(Ti_1−yZr_y)₂O₇ with y≤0.5 are amorphous, although significant short-range order is present. Contrasting to this behavior, compositions with y≥0.75 retain crystallinity in the defect fluorite structure following irradiation. The local structures of Zr⁴⁺ in the irradiated Gd₂(Ti_1−yZr_y)₂O₇ with y≥0.75 determined by NEXAFS are the same as in the cubic fluorite-structured yttria-stabilized zirconia (Y–ZrO₂), thereby providing conclusive evidence for the phase transformation. The TiO₆ octahedra present in Gd₂(Ti_1−yZr_y)₂O₇ are completely modified by ion-beam irradiation to TiO_x polyhedra, and the Ti coordination is increased to eight with longer Ti–O bond distances. The similarity between cation sites and the degree of disorder in Gd₂Zr₂O₇ facilitate the rearrangement and relaxation of Gd, Zr, and O ions/defects. This inhibits amorphization during the ion-beam-induced phase transition to the radiation-resistant defect fluorite structure, which is in contrast to the ordered Gd₂Ti₂O₇.

Keywords

Atomic orbitals; Gadolinium; Titanium; X-ray Absorption Near Edge Structure; Zirconium

Disciplines

Analytical Chemistry | Atomic, Molecular and Optical Physics | Biological and Chemical Physics | Elementary Particles and Fields and String Theory | Physical Chemistry

Language

English

Permissions

Copyright American Institute of Physics, used with permission

Repository Citation

Nachimuthu, P., Thevuthasan, S., Shutthanandan, V., Adams, E. M., Weber, W. J., Begg, B. D., Shuh, D. K., Lindle, D. W., Gullikson, E. M., Perera, R. C. (2005). Near-Edge X-ray Absorption Fine Structure Study of Ion-beam-induced Phase Transformation in Gd2(Ti1-yZry)2O7. Journal of Applied Physics, 97(033518), 6.
https://digitalscholarship.unlv.edu/chem_fac_articles/47