Defect interactions and ionic transport in scandia stabilized zirconia
R Devanathan1, S Thevuthasan, J D Gale
1Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA. ram.devanathan@pnl.gov
Physical Chemistry Chemical Physics : PCCP
|June 25, 2009
Summary
Ionic transport in zirconia is optimized at 6 mol% scandia doping. Oxygen vacancies interact with dopants differently based on temperature, influencing diffusion pathways and cluster formation.
Area of Science:
- Solid-state chemistry
- Materials science
- Computational materials science
Background:
- Zirconia-based ceramics are vital solid electrolytes.
- Understanding ionic transport mechanisms is crucial for optimizing their performance.
- Doping zirconia with scandia (Sc2O3) and yttria (Y2O3) significantly impacts ionic conductivity.
Purpose of the Study:
- To investigate ionic transport in scandia-stabilized zirconia (ScSZ) and scandia-yttria-co-doped zirconia.
- To elucidate the role of dopant composition and temperature on oxygen diffusion.
- To understand defect interactions and their influence on oxygen vacancy migration.
Main Methods:
- Classical molecular dynamics simulations were employed.
- Simulations were conducted as a function of temperature and dopant composition.
- Analysis focused on oxygen diffusion coefficients and defect site preferences.
Main Results:
- A peak in the oxygen diffusion coefficient was observed at 6 mol% Sc2O3 doping.
- At temperatures >= 1125 K, oxygen vacancies preferentially associate with scandium (first neighbor) and yttrium (second neighbor) ions.
- Electrostatic effects primarily govern defect interactions in ScSZ.
- Oxygen migration is less hindered by Sc-Sc edges compared to Y-Y edges.
- Formation of neutral dopant-anion vacancy clusters is favored.
Conclusions:
- The optimal composition for ionic transport in this system is around 6 mol% Sc2O3.
- Dopant-vacancy interactions are temperature-dependent and electrostatic in nature.
- Understanding these interactions is key to designing advanced solid electrolytes.
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