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Charge localization increases chemical expansion in cerium-based oxides.
Dario Marrocchelli1, Sean R Bishop, Harry L Tuller
1Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. dmarrocc@mit.edu byildiz@mit.edu
Physical Chemistry Chemical Physics : PCCP
|July 25, 2012
Summary
Electronic charge localization significantly boosts the chemical expansion coefficient in ceria-based materials. This finding impacts the design of advanced materials and the accuracy of ionic radii predictions.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Computational Materials Science
Background:
- Chemical expansion is a critical property for materials used in harsh environments.
- Understanding charge localization effects is key to predicting material behavior.
- Previous studies noted correlations between charge localization and chemical expansion.
Purpose of the Study:
- To elucidate the mechanism linking electronic charge localization to the chemical expansion coefficient.
- To quantify the impact of charge localization on chemical expansion in specific materials.
- To inform the design of materials with tailored expansion properties.
Main Methods:
- Utilizing Density Functional Theory (DFT) calculations.
- Investigating two model systems: cerium dioxide (CeO(2-δ)) and barium cerate (BaCeO(3-δ)).
- Analyzing the relationship between charge localization and the chemical expansion coefficient.
Main Results:
- Predicted a >70% increase in the chemical expansion coefficient upon full charge localization.
- Demonstrated a direct correlation: less localization leads to smaller expansion coefficients.
- Confirmed the mechanism in both CeO(2-δ) and BaCeO(3-δ) systems.
Conclusions:
- Electronic charge localization is a primary driver for increased chemical expansion.
- Findings provide a pathway for designing materials with reduced chemical expansion.
- The study impacts the reliability of Shannon's ionic radii in materials science.
