COMPOSITIONAL AND TEMPERATURE EFFECTS ON 5-COORDINATED SILICON IN AMBIENT-PRESSURE SILICATE-GLASSES

Citation
Jf. Stebbins et P. Mcmillan, COMPOSITIONAL AND TEMPERATURE EFFECTS ON 5-COORDINATED SILICON IN AMBIENT-PRESSURE SILICATE-GLASSES, Journal of non-crystalline solids, 160(1-2), 1993, pp. 116-125
Citations number
55
Categorie Soggetti
Material Science, Ceramics
ISSN journal
00223093
Volume
160
Issue
1-2
Year of publication
1993
Pages
116 - 125
Database
ISI
SICI code
0022-3093(1993)160:1-2<116:CATEO5>2.0.ZU;2-0
Abstract
Using Si-29 magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, silicon coordinated by five oxygens has recently been fo und in a number of alkali silicate glasses quenched from liquids both at high and ambient pressure. In this report, both the presence of thi s species in other ambient-pressure samples and the increase in its co ncentration with fictive temperature are confirmed. However, it has no t been possible to detect this species in a hydrated cesium silicate g lass sample or in a silica gel, the latter at a detection limit of abo ut 0.02%. Also as previously noted for high-pressure samples, it is fo und that five-coordinated Si is more abundant in K2Si4O9 than in Na2Si 4O9 glass. Given the effects of alkali size on the coordination and bo nding to oxygen known from crystalline silicates, this finding support s a mechanism for the formation of the high-coordinate species that in volves the consumption of non-bridging oxygens.