Influence of water on the physical properties of fluoride glass

Abstract

Several physical properties of ZBLAN glass, including their characteristic transformation temperatures, density, refractive index and ultrasonic velocity, were studied as a function of their residual water content. A series of samples with OH concentrations up to ∼ 0.0043 mol dm-3 was prepared. The OH content was determined for the partially hydrated glasses from FTIR measurements, using a known molar extinction coefficient value for the 2.9 μm band, assigned to fundamental OH stretching vibrations in Zr{single bond}OH species. Molecular H2O was not found at the present levels of water concentration. The preliminary results obtained indicate that an increase in the OH concentration causes a decrease of the density and refractive index values, similar to what has been observed in v-SiO2, as opposed to the case of silicate glasses. This behavior was not expected, since ZBLAN glass has a complex structure closer to that of modified silicates than to v-SiO2. The effect of the OH concentration on the other physical properties was generally found to coincide with known trends for silicate glasses. © 1992 Elsevier Science Publishers B.V. All rights reserved.