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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Investigating the order-disorder phase transition in Nd2-xYxZr2O7via diffraction and spectroscopy
Peter E R Blanchard1, Samuel Liu, Brendan J Kennedy
1School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia. B.Kennedy@chem.usyd.edu.au.
Dalton Transactions (Cambridge, England : 2003)
|August 31, 2013
Summary
The pyrochlore-defect fluorite phase transition in Nd2-xYxZr2O7 was studied. Yttrium cations prefer ordered environments, while Zirconium cations prefer disordered environments near the phase boundary.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- The Nd2Zr2O7 and Y2Zr2O7 systems exhibit pyrochlore and defect-fluorite structures.
- Understanding phase transitions in mixed-metal zirconates is crucial for advanced material applications.
Purpose of the Study:
- Investigate the pyrochlore-defect fluorite phase transition in the Nd2-xYxZr2O7 solid solution.
- Determine the cation ordering and local coordination environment changes across the phase transition.
Main Methods:
- Synchrotron X-ray diffraction
- Neutron diffraction
- X-ray absorption spectroscopy (XAS)
- X-ray near-edge structure (XANES) analysis
Main Results:
- A two-phase region was identified between x = 1.0 and x = 1.2.
- Zr L3-edge XANES revealed increasing disorder at the B site with Y substitution in the pyrochlore phase.
- Y L3-edge XANES indicated Y cations maintain ordered coordination in the pyrochlore phase, with disorder increasing upon fluorite phase formation.
Conclusions:
- Yttrium cations preferentially occupy ordered coordination environments near the phase boundary.
- Zirconium cations exhibit a preference for disordered coordination environments.
- The study elucidates cation behavior during the phase transition in mixed-metal zirconates.
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