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Title: Fast ion conductivity in strained defect-fluorite structure created by ion tracks in Gd 2Ti 2O 7

In this research, the structure and ion-conducting properties of the defect-fluorite ring structure formed around amorphous ion-tracks by swift heavy ion irradiation of Gd 2Ti 2O 7 pyrochlore are investigated. High angle annular dark field imaging complemented with ion-track molecular dynamics simulations show that the atoms in the ring structure are disordered, and have relatively larger cation-cation interspacing than in the bulk pyrochlore, illustrating the presence of tensile strain in the ring region. Density functional theory calculations show that the non-equilibrium defect-fluorite structure can be stabilized by tensile strain. The pyrochlore to defect-fluorite structure transformation in the ring region is predicted to be induced by recrystallization during a melt-quench process and stabilized by tensile strain. Static pair-potential calculations show that planar tensile strain lowers oxygen vacancy migration barriers in pyrochlores, in agreement with recent studies on fluorite and perovskite materials. From these results, it is suggested that strain engineering could be simultaneously used to stabilize the defect-fluorite structure and gain control over its high ion-conducting properties.
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Wyoming, Laramie, WY (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231; AC05-00OR22725
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 2045-2322
Nature Publishing Group
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; fuel cells; materials science; 36 MATERIALS SCIENCE; Pyrochlore; Radiation Damage; Ion Track; Oxygen Diffusion
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1286870