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

Elena S. Zhitova, H. Chris Greenwell, Mariya G. Krzhizhanovskaya, David C. Apperley, Igor V. Pekov, Victor N. Yakovenchuk

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

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 25–1000C, with thermal analyses of these minerals and their annealed forms carried out in parallel. In the temperature range from 25C to 170–210C 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 > 170–210C. The high-temperature modified states were stable up to 380–420C, before decomposing to an amorphous phase. Iowaite (chloride member of the family) was stable up to 320C 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 25–200C, reaching a plateau at a temperature range of 200–320C. Assessing the reversibility of thermal transformation shows complete reconstruction of the crystal structure of the hydrotalcite and iowaite heated to 300C. 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 125C 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.

Original languageEnglish
Article number961
Number of pages19
JournalMinerals
Volume10
Issue number11
DOIs
StatePublished - 28 Oct 2020

Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Geology

Keywords

  • High-temperature behavior
  • High-temperature crystal chemistry
  • Hydrotalcite supergroup
  • Iowaite
  • Layered double hydroxides
  • LDH
  • Powder X-ray diffraction
  • Quintinite
  • Stichtite
  • Thermal decomposition
  • Thermal degradation
  • Thermal evolution
  • Thermogravimetric analysis

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