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Thermal Evolution of Natural Layered Double Hydroxides: Insight from Quintinite, Hydrotalcite, Stichtite, and Iowaite as Reference Samples for CO3- and Cl-Members of the Hydrotalcite Supergroup

Zhitova, E.S.; Greenwell, H.C.; Krzhizhanovskaya, M.G.; Apperley, D.C.; Pekov, I.V.; Yakovenchuk, V.N.

Thermal Evolution of Natural Layered Double Hydroxides: Insight from Quintinite, Hydrotalcite, Stichtite, and Iowaite as Reference Samples for CO3- and Cl-Members of the Hydrotalcite Supergroup Thumbnail


Authors

E.S. Zhitova

M.G. Krzhizhanovskaya

D.C. Apperley

I.V. Pekov

V.N. Yakovenchuk



Abstract

In Situ high-temperature powder X-ray diffraction experiments were undertaken for the coarse crystalline natural layered double hydroxides (LDHs) quintinite, hydrotalcite, stichtite, and iowaite in the temperature range 25–1000 °C, with thermal analyses of these minerals and their annealed forms carried out in parallel. In the temperature range from 25 °C to 170–210 °C quintinite, hydrotalcite, and stichtite (carbonate members of the LDH family) demonstrated contraction of the basal d00n-value of 0.1–0.3 Å, followed by a sharp contraction of 1.0–1.1 Å at T > 170–210 °C. The high-temperature modified states were stable up to 380–420 °C, before decomposing to an amorphous phase. Iowaite (chloride member of the family) was stable up to 320 °C and transformed to an amorphous phase at higher temperature. Iowaite experiences continuous contraction of the d00n-value of up to 0.5 Å in the temperature range 25–200 °C, reaching a plateau at a temperature range of 200–320 °C. Assessing the reversibility of thermal transformation shows complete reconstruction of the crystal structure of the hydrotalcite and iowaite heated to 300 °C. Solid-state nuclear magnetic resonance analysis shows that some Al changes coordination from 6- to 4-fold, synchronously with quintinite transformation to the amorphous phase. All phases transform to periclase and a spinel-type compound upon further heating. Thermal analysis of samples annealed at 125 °C shows that carbonate members do not have a tendency to form dehydrated phases, whereas for iowaite, a dehydrated phase having 0.9 apfu lesser water content as in the initial sample has been obtained. Thermal evolution of LDHs is found to depend on the nature of the interaction of interlayer species and water molecules to H atoms of the metal-hydroxide layer.

Citation

Zhitova, E., Greenwell, H., Krzhizhanovskaya, M., Apperley, D., Pekov, I., & Yakovenchuk, V. (2020). Thermal Evolution of Natural Layered Double Hydroxides: Insight from Quintinite, Hydrotalcite, Stichtite, and Iowaite as Reference Samples for CO3- and Cl-Members of the Hydrotalcite Supergroup. Minerals, 10(11), Article 961. https://doi.org/10.3390/min10110961

Journal Article Type Article
Acceptance Date Oct 27, 2020
Online Publication Date Oct 28, 2020
Publication Date 2020-11
Deposit Date Oct 27, 2020
Publicly Available Date Oct 28, 2020
Journal Minerals
Electronic ISSN 2075-163X
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 10
Issue 11
Article Number 961
DOI https://doi.org/10.3390/min10110961
Public URL https://durham-repository.worktribe.com/output/1259052

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).






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