Effect of pressure on the short-range structure and speciation of carbon in alkali silicate and aluminosilicate glasses and melts at high pressure up to 8 GPa: 13C, 27Al, 17O and 29Si solid-state NMR study

2018 ◽  
Vol 224 ◽  
pp. 327-343 ◽  
Author(s):  
Eun Jeong Kim ◽  
Yingwei Fei ◽  
Sung Keun Lee
Keyword(s):  
High Pressure ◽  
Solid State ◽  
Solid State Nmr ◽  
Short Range ◽  
Effect Of Pressure ◽  
Aluminosilicate Glasses ◽  
Alkali Silicate ◽  
Nmr Study ◽  
Short Range Structure

Solid State NMR Study of Calcium Fluoroaluminosilicate Glasses

2008 ◽  
Vol 39-40 ◽  
pp. 25-30 ◽  
Author(s):  
Natalia Karpukhina ◽  
Robert V. Law ◽  
Robert G. Hill
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Base Point ◽  
29Si Nmr ◽  
Upfield Shift ◽  
Aluminosilicate Glasses ◽  
Steel Making ◽  
Nmr Study ◽  
Calcium Cations ◽  
Calcium Aluminosilicate

Fluorine containing calcium aluminosilicate glasses are widely used for a number of technological applications including dental cements, mould fluxes in steel making and in a variety of glass-ceramic systems. Despite of their importance these systems remain quite poorly understood with respect to their composition. To address this question a glass composition corresponding to the equimolar binary system anorthite−fluorite (Ca2Al2Si2O8−CaF2) was chosen as a base point for two series of compositions. One of the series is designed on the anorthite stoichiometry and considered as classically charge balanced. Another series starts from the fluorine free composition of the anorthite−lime (Ca2Al2Si2O8−CaO) stoichiometry and, therefore, is characterized by a disrupted network with at least one non-bridging oxygen (NBO) attached to silicon. A multinuclear 19F, 27Al, 29Si solid state NMR study of the glasses was undertaken. It is shown that in both series fluorine is predominantly coordinated by calcium, F−Ca(n), and in addition interacts with aluminium forming Al−F−Ca(n) complexes, where n denotes the number of first neighbouring calcium cations. Small amounts of high coordinated aluminium grows with increasing fluoride content in both glass series. However, the high coordinated aluminium may not be solely due to the formation of the Al−F−Ca(n) complexes. Glasses of the first series displayed systematic upfield shift of 29Si NMR resonance while substituting fluoride for oxide, starting from the fluorine free composition. This upfield shift is interpreted as the lack of cations in the network, due to formation of the F−Ca(n), which drives silicon network to polymerize toward a higher Qn structure. Contrary to the first series, the 29Si NMR resonance remains constant for fluorine containing compositions of the second series but differs downfield from the initial anorthite glass. The latter is explained by the excess of cations in the network due to addition of the fluorite resulting in formation of NBO on the silicon. Binding of fluorine with silicon is considered negligible in these systems. Thus, fluorine and calcium both define the degree of network polymerization and are considered as a cause for the changes in silicon and aluminium networks.

The adsorption of chromocene and ferrocene on silica: A solid-state NMR study

2013 ◽  
Vol 744 ◽  
pp. 119-124 ◽  
Author(s):  
Kyle J. Cluff ◽  
Michael Schnellbach ◽  
Casie R. Hilliard ◽  
Janet Blümel
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Nmr Study
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