Glass, forming

Tokmakoff A and Fayer M D 1995 Homogeneous vibrational dynamics and inhomogeneous broadening in glass-forming liquids infrared photon echo experiments from room temperature to 10 KJ. Chem. Phys. 103 2810-26... 

The action of concentrated sulphuric acid liberates hydrogen fluoride, which attacks glass, forming silicon tetrafluoride the latter is hydrolysed to silicic acid by water, which therefore becomes turbid,... 

Glass-forming systems other than siUca have been examined. The fraction of three- and four-coordinated boron in borate glasses can be determined by nmr (29). Both nmr and x-ray diffraction (30) results led to the suggestion that the boroxyl ring is the stmctural unit of vitreous The... 

H. Rawson, Inorganic Glass-Forming Systems, Academic Press, Inc., London, 1967. 

Vitreous siUca is considered the model glass-forming material and as a result has been the subject of a large number of x-ray, neutron, and electron diffraction studies (12—16). These iavestigations provide a detailed picture of the short-range stmcture ia vitreous siUca, but questioas about the longer-range stmcture remain. 

Although boron phosphate is derived from two of the three most common glass-forming oxides, it exhibits Htde tendency to form a glass itself. Boron phosphate is a primary phase over a considerable portion of the B2O2—Si02—P20 system (159). 

Carbonate Glasses. Carbonate glasses must be melted under moderate pressures to prevent the escape of carbon dioxide gas. The simplest carbonate glass forming system is K CO —MgCO. ... 

Glass-Transition Temperature. When a typical Hquid is cooled, its volume decreases slowly until the melting point, T, where the volume decreases abmpdy as the Hquid is transformed into a crystalline soHd. This phenomenon is illustrated by the line ABCD in Eigure 3. If a glass forming Hquid is cooled below (B in Eig. 3) without the occurrence of crystallization, it is considered to be a supercooled Hquid until the glass-transition temperature, T, is reached. At temperatures below T, the material is a soHd. 

Glasses formed by the sol—gel method are very homogeneous and can be made very pure. In general, there is Httle or no difference between the physical properties of sol—gel and melt-formed glasses of identical composition, but some researchers have reported stmctural differences. One drawback... 

D.R. Uhlmann and NJ. Kiiedel. Glass Science and Technology, Vol. I (Glass forming systems). Academic Piess (1983) TP848 G56. 

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