Comparison of the crystal chemistry of selected MSi_6O_(15)-based silicates
- Creators
-
Haile, S. M.
- Wuensch, B. J.
Abstract
The structures of four A(3)MSi(6)O(15)(. nH(2)O) silicates (A = Na or K, M = Nd or Y) recently determined by the authors are compared with one another and with the structures of related silicates. The 2:5 Si:O ratio in these compounds (silicate tetrahedra linked by sharing three O atoms per tetrahedron plus one unshared O atom) permits layer, double-chain, or double-ring configurations. In alpha-K3NdSi6O15. 2H(2)O, beta-K3NdSi6O15, and Na3NdSi6O15. 2H(2)O, the linkage is found to result in a corrugated layered structure, in beta-Na3YSi6O15 a double-chain structure, and in alpha-Na3YSi6O15 a unique double-ring structure. Although the factors that govern the stabilities of ring vs. chain vs. layered structures remain to be completely elucidated, it is apparent in the layered structures that larger M cations (such as Nd and Ce) produce a greater degree of corrugation than do Zr and Ti cations. The more open structures of neodymium and cerium silicates contain large channels that may serve as pathways for fast alkali ion transport.
Additional Information
Copyright © 1997 by the Mineralogical Society of America. MANUSCRIPT RECEIVED FEBRUARY 14, 1997. MANUSCRIPT ACCEPTED JULY 30, 1997. We thank Robert Laudise of Lucent Technologies for his support and enthusiasm for this work, and for providing access to hydrothermal synthesis facilities. Karl Peters of the Max-Planck Institute für Festkörperforschung, Stuttgart, kindly collected the single-crystal intensity data. We are grateful to Mike Jercinovic of the Massachusetts Institute of Technology for performing the electron probe microanalyses. F. Liebau and M. E. Fleet provided valuable comments for which we are grateful.Additional details
- Eprint ID
- 42719
- Resolver ID
- CaltechAUTHORS:20131125-162532106
- Created
-
2013-12-02Created from EPrint's datestamp field
- Updated
-
2019-10-03Created from EPrint's last_modified field