Award Date

May 2019

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics and Astronomy

First Committee Member

Ashkan Salamat

Second Committee Member

Oliver Tschauner

Third Committee Member

Jason Steffen

Fourth Committee Member

Stephen Lepp

Fifth Committee Member

Paul Forster

Number of Pages

43

Abstract

The recent surge in exoplanet discoveries due to advancements in astrophysical technology and analysis has brought the reliability of early equation of state measurements into question as they are the limiting factor when modeling composition of these planets. H2O content is among the most important for the search of habitable planets as well as in understanding planetary dynamics and atmosphere formation. Over the last three decades the equation of state of H2O has been investigated with various techniques but, has suffered from anisotropic strain and poor powder statistics resulting in a large discrepancy in equation of state fits. At pressures within the interior of many planets, the hydrogen bonds in H2O gradually weaken and are replaced by ionic bonds in ice-X. By melt-recrystallization of ice via laser heating as it is compressed, we observe the transition from ice-VII to ice X at a pressure of 30.9 ± 2.9 GPa, evidenced by an abrupt 2.5-fold increase in bulk modulus, implying an increase in bond strength. This transition is preceded by a modified ice structure of tetragonal symmetry, ice-VIIt.

Keywords

Equation of state; H2O; Ice-VII; X-ray diffraction

Disciplines

Condensed Matter Physics | Engineering Science and Materials | Materials Science and Engineering

Language

English


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