Thesis Defense Announcement

The College of Arts and Sciences announces the Final Thesis Defense of

Zhi Song

for the Degree of Master of Science

October 30, 2018 at 1:00 PM in Manning Hall

Advisor: Xiao Shen

Modeling of electrical dipole switching in phosphorsilicate glass

ABSTRACT: A number of experimental studies have reported that phosphorsilicate glass (PSG) exhibits switchable electrical polarization like ferroelectric materials. However, the mechanism of electrical dipole switching is not understood, even though some hypothesis exists. The present work constructs an atomistic model of the switchable polarization in PSG by mainly using a bond-switching algorithm. In addition, the density functional theory, the BFGS algorithm, and molecular dynamics were implemented to optimize the structures. The initial system of amorphous silicon dioxide used to construct models of PSG was generated by the bond-switching algorithm and the Metropolis Monte Carlo method. The most likely structures of PSG have been obtained to investigate the polarization switching. A plausible mechanism was unveiled to explain the dipole switching in which the migration of an oxygen atom causes the transition between a nonpolarized state and a polarized state. Final, we propose a feasible approach of decreasing the energy barrier of switching for practical applications.