Hydrothermal synthesis of new alkali silicates II. Sodium neodymium and sodium yttrium phases
- Creators
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Haile, S. M.
- Wuensch, B. J.
- Laudise, R. A.
Abstract
Hydrothermal techniques have been utilized to synthesize three sodium neodymium and seven sodium yttrium silicates as potential new fast ion conductors (FICs). We describe here the conditions which led to the crystallization of NaNdSi_6O_(14), Na_3NdSi_6O_(15)· 5H_2O, NaNd_9(SiO_4)_6O_2, Na_3YSi_6O_(15), Na_3YSi_7O_(17), Na_7YSi_(12)O_(29), Na_3YSi_3O_9, Na_5YSi_4O_(12), Na_6YSi_(13)O_(29)(OH)_3, and NaYSi_6O_(14), six of which are previously unreported. The compositions of new phases were determined from electron microprobe measurements and flame spectroscopy. Syntheses were carried out in aqueous solutions of NaOH, Na_2CO_3, NaF, NaHF_2, at pressures, temperatures, and molarities ranging from 0.5 to 1.4 kbar, from 350 to 600°C, and from 0 to 10M, respectively. Results obtained in these sodium systems are compared with those of the potassium neodymium silica system, reported in Part I. Consistent with the earlier observations, crystallization at high temperatures, high solution molarities and, to some extent, high pressures tended to yield phases of low silica content and low silicon to oxygen ratios, and hence low structural connectivity of the tetrahedra in the silica framework.
Additional Information
Copyright © 1993 Elsevier. Received 27 March 1993. Accepted 20 April 1993. Many thanks are due to Anthony J. Caporaso (AT&T Bell Laboratories) for instruction and guidance in the hydrothermal technique and Bill Grodkiewicz (AT&T Bell Laboratories) for aid in glass preparation. We are indebted to Mike Jercinovic (Massachusetts Institute of Technology) and Ortrud Buresch (Max-Planck-Institut für Festkörperforschung) for assistance with composition determinations from WDX and flame spectroscopy measurements, respectively. The authors are also grateful to Dr. Karl Peters (Max-Planck-Institut für Festkörperforschung), who has kindly provided single crystal intensity data for some phases. S. Haile additionally acknowledges the generous financial support of the AT&T Cooperative Fellowship Research Program.Additional details
- Eprint ID
- 42721
- DOI
- 10.1016/0022-0248(93)90186-Z
- Resolver ID
- CaltechAUTHORS:20131125-162532325
- AT&T Cooperative Fellowship
- Created
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2013-12-03Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field