TY - JOUR
T1 - A structural investigation of CaO-Al2O3 glasses via 27Al MAS-NMR
AU - McMillan, Paul F.
AU - Petuskey, William
AU - Coté, Bertrand
AU - Massiot, Dominique
AU - Landron, Claude
AU - Coutures, Jean Pierre
N1 - Funding Information:
This study was supported in part by NSF grant EAR-9219504 to PFM and NSF-CNRS travel grant INT-9115888 to PFM and JPC. WTP is indebted to Prof. Masahiro Yoshimura of Tokyo Institute of Technology for use of Xe arc thermal imaging furnace used to prepare one series of splat quenched samples. JPC, DM, CL and BC acknowledge CNRS (Chemistry Science Dept., Ultimatech and PIRMAT programs) for support of the high temperature and NMR experiments. The authors thank A. Douy, J.C. Rifflet and B.T. Poe for valuable discussion and help in preparing samples. They also thank an anonymous reviewer and R.A. Weeks for editorial comments, which improved the manuscript.
PY - 1996/3
Y1 - 1996/3
N2 - 27Al Isotropic chemical shifts and quadrupolar coupling constants have been obtained for glasses along the CaO-Al2O3 join, prepared by fast (splat) quench techniques and slow cooling in containerless levitation experiments. Quench rates with the two techniques were 106-107°/s and 200-300°/s. Fast-quenched glasses with CaO:Al2O3 < 1 contain Al in V-and VI-coordination to oxygen, in addition to the dominant IV-coordinated species. Glasses along the CaO-CaAl2O4 portion of the join contain only IV-coordinated aluminium. The average isotropic chemical shift of these glasses increases with increasing CaO content, which may reflect a decrease in the polymerization state of the aluminate units, although a similar trend can not be detected in the corresponding crystals. The chemical shifts for the fast quenched glasses are displaced systematically to smaller values, which can be associated with a rearrangement of Ca and Al in the next nearest neighbour coordination environment about the central Al atom. The fast quenched glasses have a less ordered, more distorted structure, as revealed by larger values of the quadrupolar coupling constant, and Al XANES spectra.
AB - 27Al Isotropic chemical shifts and quadrupolar coupling constants have been obtained for glasses along the CaO-Al2O3 join, prepared by fast (splat) quench techniques and slow cooling in containerless levitation experiments. Quench rates with the two techniques were 106-107°/s and 200-300°/s. Fast-quenched glasses with CaO:Al2O3 < 1 contain Al in V-and VI-coordination to oxygen, in addition to the dominant IV-coordinated species. Glasses along the CaO-CaAl2O4 portion of the join contain only IV-coordinated aluminium. The average isotropic chemical shift of these glasses increases with increasing CaO content, which may reflect a decrease in the polymerization state of the aluminate units, although a similar trend can not be detected in the corresponding crystals. The chemical shifts for the fast quenched glasses are displaced systematically to smaller values, which can be associated with a rearrangement of Ca and Al in the next nearest neighbour coordination environment about the central Al atom. The fast quenched glasses have a less ordered, more distorted structure, as revealed by larger values of the quadrupolar coupling constant, and Al XANES spectra.
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U2 - 10.1016/0022-3093(95)00536-6
DO - 10.1016/0022-3093(95)00536-6
M3 - Article
AN - SCOPUS:0030104673
SN - 0022-3093
VL - 195
SP - 261
EP - 271
JO - Journal of Non-Crystalline Solids
JF - Journal of Non-Crystalline Solids
IS - 3
ER -