TY - JOUR
T1 - Crystal chemistry and phase transitions in substituted pollucites along the CsAlSi2O6-CsTiSi2O6.5 join
T2 - A powder synchrotron x-ray diffractometry study
AU - Xu, Hongwu
AU - Navrotsky, Alexandra
AU - Balmer, M. Lou
AU - Su, Yali
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2002/5
Y1 - 2002/5
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0036573213&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0036573213&partnerID=8YFLogxK
U2 - 10.1111/j.1151-2916.2002.tb00251.x
DO - 10.1111/j.1151-2916.2002.tb00251.x
M3 - Article
AN - SCOPUS:0036573213
SN - 0002-7820
VL - 85
SP - 1235
EP - 1242
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 5
ER -