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Synthesis and Microdiffraction at Extreme Pressures and Temperatures
Published on: October 8, 2013
Collapsing cristobalitelike structures in silica analogues at high pressure
J Haines1, C Chateau, J M Léger
1Laboratoire de Physico-Chimie de la Matière Condensée, UMR CNRS 5617, Université Montpellier II, cc 003, Place E. Bataillon, 34095 Montpellier Cedex 5, France.
Physical Review Letters
|August 9, 2003
Summary
High pressure transforms boron phosphate (BPO4) and boron arsenate (BAsO4) into a collapsed cristobalite structure. This study reveals a continuous framework collapse without phase transitions.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- Cristobalite is a high-temperature polymorph of silica with a framework structure.
- Ternary silica analogues like BPO4 and BAsO4 share structural similarities with cristobalite.
- Understanding framework behavior under pressure is crucial for materials design.
Purpose of the Study:
- To investigate the high-pressure behavior of cristobalitelike BPO4 and BAsO4.
- To characterize the structural transformations and topological changes in these compounds.
- To explore the continuous collapse of framework structures.
Main Methods:
- High-pressure X-ray diffraction (XRD) studies.
- First-principles theoretical calculations.
- Analysis of tetrahedral tilt angles and framework topology.
Main Results:
- BPO4 and BAsO4 exhibit a significant increase in tetrahedral tilt angles under high pressure.
- A continuous topological transformation from a cristobalitelike to a
Conclusions:
- BPO4 and BAsO4 demonstrate an extreme case of framework structural collapse.
- These compounds are the first examples of continuous framework collapse to a close-packed form without phase transitions.
- The findings offer new insights into the pressure-induced structural evolution of framework materials.
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