MRS Meetings and Events

 

DS01.05.02 2022 MRS Fall Meeting

Heat Capacity of Dense Post-Stishovite Silica Glass from Fast-Scanning Calorimetry

When and Where

Nov 29, 2022
8:00pm - 10:00pm

Hynes, Level 1, Hall A

Presenter

Co-Author(s)

Laura Bonatti1,B Brugman1,Tamilarassan Subramani1,Sergey Ushakov1,Kurt Leinenweber1,Alexandra Navrotsky1

Arizona State University1

Abstract

Laura Bonatti1,B Brugman1,Tamilarassan Subramani1,Sergey Ushakov1,Kurt Leinenweber1,Alexandra Navrotsky1

Arizona State University1
Stishovite is a high-pressure phase of SiO<sub>2</sub> which transforms into a dense glass when heated at ambient pressure to ~500°C. The properties of post-stishovite glass are more similar to densified silica formed by compression above 10 GPa than to standard fused quartz. Despite widespread thermal data on crystalline and glassy SiO<sub>2</sub> phases, the heat capacity of the dense, post-stishovite glass has not been measured. We calibrated a Mettler Toledo Flash DSC 2+ to determine quantitively the mean heat capacity for post-stishovite glass, as well as crystalline stishovite and TiO<sub>2</sub> in the temperature range of 200 to 350 <sup>o</sup>C. The calibration was performed using the heat capacity of alumina, titania and zirconia, with an uncertainty of under 17%. Our measured Cp for titania and stishovite agrees within 9% of the reported literature values. The heat capacity for the post-stishovite glass was within 6.6% of the reported literature value for the heat capacity of stishovite between 200 to 350 <sup>o</sup>C. The developed methodology allows for obtaining quantitative thermochemical data on solid samples in micrograms amounts that are too small for other methods, e.g. new high pressure phases quenched from diamond anvil cell experiments.

Keywords

phase transformation | thermodynamics

Symposium Organizers

Wenhao Sun, University of Michigan
Alexandra Khvan, National Research Technological University
Alexandra Navrotsky, Arizona State University
Richard Otis, NASA Jet Propulsion Laboratory

Publishing Alliance

MRS publishes with Springer Nature