Crystal chemistry and phase transitions in substituted pollucites along the CsAlSi2O6-CsTiSi2O6.5 join: A powder synchrotron x-ray diffractometry study

Hongwu Xu, Alexandra Navrotsky, M. Lou Balmer, Yali Su

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The crystal structures for a suite of substituted pollucites with the compositions CsTixAl1-xSi2O6+0.5x, 0 ≤ x ≤1, have been determined from Rietveld analysis of powder synchrotron XRD data. Our results indicate that the pollucite end member (CsAlSi2O6) has a tetragonal structure (space group I41/a), whereas all other compositions are cubic (space group Ia3d). The increased symmetry for the titanium-substituted structures is presumably due to the incorporation of additional O2- anions (needed for compensating the charge imbalance between Ti4+ and Al3+), which effectively holds open the expanded cubic framework. In situ cooling experiments of the substituted phase CsTi0.1Al0.9Si2O6.05 reveal a displacive transformation to the tetragonal structure at ∼230 K. This transformation is tricritical in nature and is analogous to the tetragonal-to-cubic transition in pollucite on beating.

Original languageEnglish (US)
Pages (from-to)1235-1242
Number of pages8
JournalJournal of the American Ceramic Society
Issue number5
StatePublished - May 2002
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry


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