Abstract
We have systematically investigated the elastic properties (ρ, VP, VS, K, μ and σ) of eight SiO2–TiO2 glasses, varying in composition from 1.3 to 14.7 wt% TiO2, as a function of pressure up to 0.5 GPa by the pulse superposition (PSP) ultrasonic technique, and two compositions (1.3 and 9.4 wt% TiO2) up to ~5.7 GPa by Brillouin scattering in a diamond anvil cell. The parameters were also measured after annealing to 1020 °C. Composition–elasticity relationships, except for K and σ, are more or less linear; the annealing simply makes the relationships more uniform (less scatter). There is excellent agreement between the ultrasonic and Brillouin measurements at ambient and high pressure. The pressure-induced anomalous elastic behavior (negative dVP/dP and dK/dP) becomes more negative (more compressible) with the increasing TiO2 content. Correspondingly, the acoustic Grüneisen parameters become more negative with increases in the TiO2 content, reaching a minimum near ~8–10 wt% TiO2. The comparison of the low- and high-pressure ultrasonic and Brillouin VP and VS in two glasses (1.3 and 9.4 wt% TiO2) shows excellent agreement, defining the reversible elastic behavior at low pressures and irreversible behavior at higher pressures (≥5.7 GPa) well. This result is consistent with our previous high-pressure Raman study showing an irreversible structural change in a similar pressure range.
Highlights
Interest in the SiO2 –TiO2 glass system has continued to develop in view of its low thermal expansion properties and the ability to tune the coefficient of thermal expansion over wide ranges of temperature by varying compositions (TiO2 content) and/or annealing
The data for fused silica and the ULE® SiO2 –TiO2 glass (Corning Code 7971) containing 7.5 wt% TiO2 are in good agreement with the previous measurements of McSkimin and Andreatch [29] and the published
HT and changes within these glasses take place [37]. Such irreversibility is well-documented in silica glass, The mode Grüneisen parameters γi are evaluated from the pressure dependence of the acoustic with the onset of irreversible densification occurring near 9 GPa [40,41]: our results indicate that mode velocities, Vi: the onset of irreversible densification occurs at lower pressures within titania-bearing glasses relative to the SiO2 endmember
Summary
Interest in the SiO2 –TiO2 glass system has continued to develop in view of its low thermal expansion properties and the ability to tune the coefficient of thermal expansion over wide ranges of temperature by varying compositions (TiO2 content) and/or annealing. SiO2 –TiO2 glasses containing up to ~11 wt% TiO2 have been synthesized as apparently single homogeneous phases [1,2,3]. A SiO2 –TiO2 glass (ULE® , Corning Code 7971). Containing about 7.5 wt% TiO2 has been demonstrated to have a nearly zero thermal expansion [4,5]. Minerals 2020, 10, 481 thermal expansion of silica glass. Such composition-dependent variations in the thermal expansion of
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
