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Pressure-induced disordering and anomalous lattice expansion in La2Zr2O7 pyrochlore
F X Zhang1, M Lang, Zhenxian Liu
1Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA.
Physical Review Letters
|September 28, 2010
Summary
Pressure alters La2Zr2O7 pyrochlore structure, causing cation and anion disordering around 10 GPa. This may involve water incorporation, potentially linking to photoelectrochemical effects.
Area of Science:
- Materials Science
- Solid State Chemistry
- Geophysics
Background:
- La2Zr2O7 pyrochlore is a promising material for various applications.
- Understanding its behavior under pressure is crucial for material design and stability.
- Previous studies noted photoelectrochemical effects in this material.
Purpose of the Study:
- To quantitatively analyze pressure-induced disordering in La2Zr2O7.
- To investigate the structural and vibrational changes at high pressures.
- To explore potential links between pressure effects and photoelectrochemical properties.
Main Methods:
- In situ X-ray diffraction (XRD) for structural analysis.
- Rietveld refinement for quantitative structural determination.
- Raman and infrared spectroscopy for vibrational mode analysis.
Main Results:
- Observed cation and anion disordering in La2Zr2O7 under pressure.
- Identified anomalous lattice expansion around 10 GPa.
- Detected significant changes in the pressure dependence of vibrational modes at ~10 GPa.
- Evidence suggests pressure-induced water incorporation into the pyrochlore structure.
Conclusions:
- Pressure significantly impacts the La2Zr2O7 pyrochlore structure, leading to cation/anion disorder.
- A critical pressure point (~10 GPa) exists where structural and vibrational properties change anomalously.
- Pressure-induced water incorporation is a potential mechanism, possibly connecting to observed photoelectrochemical effects.
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