Issue 16, 2018

In situ synchrotron XRD analysis of the kinetics of spodumene phase transitions

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

Supplementary files

Article information

Article type
Paper
Submitted
17 nov 2017
Accepted
18 jan 2018
First published
19 jan 2018

Phys. Chem. Chem. Phys., 2018,20, 10753-10761

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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