Dielectric Loss and the States of Glass

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Abstract
Specimens of commercial plate glass were compacted at 900°F. and cooled slowly to room temperature. Power loss was determined as the specimens were reheated and quenched from various temperatures within the range 200° to 1200°F. Irreversible increases in tan δ were found to occur at quenching temperatures below the transformation range as well as within it. The increases below the transformation range are considered to result from changes in the Na + ion distribution, established during cooling, among the interstitial holes. As shown by density measurements, the increases within the transformation range are associated with configurational changes in the basic silica network. A glass property that depends on the mobility of a constituent ion is determined by at least two states: (1) a configurational state of the silica network and (2) a distribution state of the mobile ion. The extent of compaction is clearly indicated in a family of curves of tan δ vs. quenching temperature, with compacting time as a parameter.