Pseudocubic Crystal Structure
and Phase Transition
in Doped Ye’elimite
Ana Cuesta
Ángeles
G. De la Torre
Enrique R. Losilla
Isabel Santacruz
Miguel A. G. Aranda
10.1021/cg501290q.s001
https://acs.figshare.com/articles/journal_contribution/Pseudocubic_Crystal_Structure_and_Phase_Transition_in_Doped_Ye_elimite/2250721
Sodalites are tridimensional alumino-silicate
materials containing
cages where loosely bonded anions are located. Ye’elimite,
Ca<sub>4</sub>[Al<sub>6</sub>O<sub>12</sub>]SO<sub>4</sub>, is outstanding
as an aluminate sodalite with a flexible framework accepting several
type of dopants with important structural consequences. Moreover,
ye’elimite is also important from an applied perspective as
it is the most relevant phase in calcium sulfoaluminate cements. The
crystal structure of stoichiometric ye’elimite has recently
been unraveled, but the structure of dopant-containing ye’elimite,
which is present in cements, is not well studied. Here, we report
the pseudocubic crystal structure of doped ye’elimite, Ca<sub>3.8</sub>Na<sub>0.2</sub>Al<sub>5.6</sub>Fe<sub>0.2</sub>Si<sub>0.2</sub>O<sub>12</sub>SO<sub>4</sub>, from high-resolution synchrotron
powder diffraction data. The powder pattern is indexed with a cubic
cell, and a structural model is reported based on the <i>I</i>4̅3<i>m</i> space group. However, this compound displays
diffraction peak narrowing on heating. Furthermore, some high-angle
split peaks become a single peak on heating, and a phase transition
is measured at 525 °C. Therefore, it is concluded that the crystal
structure at room temperature has a lower symmetry, although it can
be described as cubic. The structural study at 800 °C suggests
a truly cubic structure, and we speculate that this phase transition,
on heating, is likely related to the dynamical disordering of the
sulfate anions. Finally it is concluded that the high temperature
cubic state was not quenchable to ambient, even when the tested chemical
substituents are introduced into the structure.
2014-10-01 00:00:00
heating
crystal structure
compound displays diffraction peak
phase transition
Pseudocubic Crystal Structure
synchrotron powder diffraction data
pseudocubic crystal structure
calcium sulfoaluminate cements