Effects of Melting Temperatures on the Structure
of Germania Glass¹

R. A. Weeks*, R. H. Magruder**, and D. L. Kinser*

* Department of Mechanical Engineering Vanderbilt University, Nashville, TN 37240, USA
** Department of Physics, Belmont College, Nashville TN, USA

Abstract—We review some data on germania, a glass classified as a “strong” glass in the “strong/fragile” clas-
sification scheme. Some of its properties were measured as a function of the temperature of the liquid from
which it was cooled to the glass. The concentrations of neutral and singly charged oxygen vacancies, oxygen-
related centers, peroxy radicals, and nonbridging oxygen hole centers were measured by electron paramagnetic
spectroscopy after cooling to a glass and, then, after irradiation with ⁶⁰Co gamma-rays. None of the measured
concentrations were in agreement with the concentrations calculated from the thermodynamic theory. The con-
centration of the oxygen-related states was several orders of magnitude greater than that calculated, while the
concentration of oxygen vacancy state—the E'-center—was approximately two orders of magnitude smaller
than calculated. The mobility of Na ions was also dependent on the temperature of the liquid from which the
glass was formed. Analysis of these data showed that changes in entropy of the material were the source of the
liquid temperature dependence. The liquid temperature effects on the mobility were still observed after an
annealing at ~15 K below the Littleton softening temperature for 56 h in air. The intensity of an optical absorp-
tion band at ~250 nm, attributed by other researchers to oxygen vacancies, did have a dependence on liquid tem-
perature that was within an order of magnitude of calculated concentrations of oxygen vacancies. There are
many defect states in germania and silica that have been shown to contribute to the absorption at ~250 nm.

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