XRPD analysis of karrooite-like metastable nanocrystalline phases

J. Zabicky, G. Kimmel, E. Goncharov, D. Dayan

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations

Abstract

A coprecipitated xerogel with Ti:Mg atomic ratio of ∼1.3:1 was annealed for 3 h, at constant temperature in the 500-1100°C range, at 100°C intervals. Rietveld refinement of the XRPD scans of the products points to the formation of karrooite-like metastable structures, with cell parameters, atomic positions and site occupancies that greatly deviate from those of conventional karrooite (MgO 2TiO2). The chosen precursor composition yields a mixture of stoichiometric geikielite (MgO TiO2) and nonstoichiometric karrooite with Ti:Mg ratio (2 - x):1; the x value calculated from the Mg and Ti occupancies found by the Rietveld refinement was 0.2 for thermal annealing at 600°C and reduced nearly to zero for annealing above 1000°C; the amount of geikielite increased as the annealing temperature increased. Excellent agreement was found between X-ray quantitative and structural analyses, Line broadening analysis shows considerable decrease of the microstrain as well as increase of crystallite size associated with the rise of the annealing temperature.

Original languageEnglish
Pages (from-to)741-746
Number of pages6
JournalMaterials Science Forum
Volume378-381
Issue numberII
DOIs
StatePublished - 1 Jan 2001
Event7th European Powder Diffraction Conference - Barcelona, Spain
Duration: 20 May 200023 May 2000

Keywords

  • Crystal growth
  • Karrooite
  • Magnesium titanates
  • Metastable phase
  • Microstrain
  • Nanocrystalline phase
  • Rietveld analysis
  • X-ray powder diffraction

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