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Issue 16, 2018
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In situ synchrotron XRD analysis of the kinetics of spodumene phase transitions

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Abstract

The phase transition by thermal activation of natural α-spodumene was followed by in situ synchrotron XRD in the temperature range 896 to 940 °C. We observed both β- and γ-spodumene as primary products in approximately equal proportions. The rate of the α-spodumene inversion is first order and highly sensitive to temperature (apparent activation energy ∼800 kJ mol−1). The γ-spodumene product is itself metastable, forming β-spodumene, with the total product mass fraction ratio fγ/fβ decreasing as the conversion of α-spodumene continues. We found the relationship between the product yields and the degree of conversion of α-spodumene to be the same at all temperatures in the range studied. A model incorporating first order kinetics of the α- and γ-phase inversions with invariant rate constant ratio describes the results accurately. Theoretical phonon analysis of the three phases indicates that the γ phase contains crystallographic instabilities, whilst the α and β phases do not.

Graphical abstract: In situ synchrotron XRD analysis of the kinetics of spodumene phase transitions

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Publication details

The article was received on 17 Nov 2017, accepted on 18 Jan 2018 and first published on 19 Jan 2018


Article type: Paper
DOI: 10.1039/C7CP07754H
Citation: Phys. Chem. Chem. Phys., 2018,20, 10753-10761
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    In situ synchrotron XRD analysis of the kinetics of spodumene phase transitions

    R. L. Moore, J. P. Mann, A. Montoya and B. S. Haynes, Phys. Chem. Chem. Phys., 2018, 20, 10753
    DOI: 10.1039/C7CP07754H

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