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Structural Transformations and Disordering in Zirconolite (CaZrTi2O7) at High Pressure

DOI: 10.1021/ic302346g DOI Help

Authors: Ashkan Salamat (University College London) , Paul Mcmillan (University College London) , Steve Firth (University College London) , Katherine Woodhead (University College London) , Andrew Hector (University of Southampton) , Gaston Garbarino (ESRF) , Martin Stennett (University of Sheffield) , Neil Hyatt (University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Inorganic Chemistry , VOL 52 (3)

State: Published (Approved)
Published: January 2013

Abstract: There is interest in identifying novel materials for use in radioactive waste applications and studying their behavior under high pressure conditions. The mineral zirconolite (CaZrTi2O7) exists naturally in trace amounts in diamond-bearing deep-seated metamorphic/igneous environments, and it is also identified as a potential ceramic phase for radionuclide sequestration. However, it has been shown to undergo radiation-induced metamictization resulting in amorphous forms. In this study we probed the high pressure structural properties of this pyrochlore-like structure to study its phase transformations and possible amorphization behavior. Combined synchrotron X-ray diffraction and Raman spectroscopy studies reveal a series of high pressure phase transformations. Starting from the ambient pressure monoclinic structure, an intermediate phase with P21/m symmetry is produced above 15.6 GPa via a first order transformation resulting in a wide coexistence range. Upon compression to above 56 GPa a disordered metastable phase III with a cotunnite-related structure appears that is recoverable to ambient conditions. We examine the similarity between the zirconolite behavior and the structural evolution of analogous pyrochlore systems under pressure.

Subject Areas: Chemistry

Instruments: I15-Extreme Conditions

Other Facilities: ESRF

Added On: 28/01/2013 08:13

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