Mineral Physics Institute Summer Scholars Program

Christopher Dodson University of Colorado - Boulder Major: Geophysics Mentor: Donald Weidner

Summer Project Description:

Perovskites exist in the lower mantle and comprehension of their physical properties helps us to determine a more accurate
compositional model of the Earth's interior. To understand, we must first have data to analyze and to collect data we must
have a sample on which we can perform experiments. With many minerals that are synthesized using high pressure and temperature
they are quenched and brought back down to standard conditions, 0 GPa, they retain the physical characteristics they had at
high pressure. Such is not the case with CaSiO 3 perovskite. When this mineral is synthesized and then quenched, it turns to an
amorphous glass, meaning that all experiments must be run while the sample is at high pressure and temperature. If one were to
synthesize the material and then bring it back to 0 GPa without running any tests while at pressure they would have no way of
knowing if what they possessed was ever CaSiO 3 perovskite. With this project, it is hoped that knowledge might be gained
as to whether the amorphous glass retains any characteristics of the perovskite, such as octahedral coordination of the silicon by oxygen.
To analyze this, powder diffraction analysis will be performed and the bond length of the silicon-oxygen will be determined using
a pair distribution function (PDF). This bond length should be able to determine how the silicon and oxygen are coordinated.