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A reappraisal of fast ion conduction in Ta, Ga and Al-substituted Aurivillius Phases

Journal Article · · Solid State Ionics
Oxygen ion conduction in the Aurivillius phases Bi{sub 2}Sr{sub 2}(Nb or Ta){sub 2}(Ga or Al)O{sub 11.5} has been evaluated in detail. High-temperature X-ray diffraction studies, coupled with differential scanning calorimetry, electron microscopy, and conductivity measurements were used to clearly demonstrate that Bi{sub 2}Sr{sub 2}(Nb{sub x}Ta{sub 1-x}){sub 2}(Ga{sub y}Al{sub 1-y})O{sub 11.5} with x = 0, 1 and y = 0, 0.5, and 1 form only multiphase specimens. The origin of the previously observed fast ion conduction is a result of interconnected Bi{sub 2}O{sub 3} grains that undergo a high-temperature phase transformation to the {delta}-Bi{sub 2}O{sub 3} polymorph. The Aurivillius phase component of the multiphase specimens does not demonstrate any type of order-disorder transformation, however, the phase transformations of the Bi{sub 2}O{sub 3} are clearly observed using high-temperature diffraction and calorimetry.
Research Organization:
Oak Ridge National Laboratory (ORNL)
Sponsoring Organization:
EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
1003261
Journal Information:
Solid State Ionics, Journal Name: Solid State Ionics Journal Issue: 35-36 Vol. 176; ISSN 0167-2738
Country of Publication:
United States
Language:
English