Glasse silicate units

Glass, rubber, and many plastics are amorphous solids. Recent studies have shown that glass may have some structure. When X-ray diffraction is used to study glass, there appears to be no pattern to the distribution of atoms. When neutrons are used instead, an orderly pattern of silicate units can be detected in some regions. Researchers hope to use this new information to control the structure of glass for optical applications and to produce glass that can conduct electricity. 

The measured potential is thus a linear function of pH an extremely wide (10-14 decades) linear range is obtained, with calibration plots yielding a slope of 59 mV per pH unit. The overall mechanism of the response is complex. The selective response is attributed to the ion-exchange properties of the glass surface, and in particular the replacement of sodium ions associated with the silicate groups in the glass by protons ... 

The main difference between a glass and its liquid is not structural but kinetic and depends on a microscopic quantity called the structural relaxation time t. This time is the mean life time for the movement of a structural unit over a distance equivalent to its size. Such a structural unit may consist of several SiO units in the case of a silicate glass. The... 

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