Migration behavior of network-modifier cations at glass surface during electrical poling

Abstract

X-ray photoelectron spectroscopy with C60-ion sputtering (C60-XPS) and electron spin resonance (ESR) revealed the migration behavior of network-modifier cations in an electrically poled soda-lime silicate glass. The Na+-deficient layer of 700-nm thickness was confirmed at the anode side surface. The Mg2+and Ca2+ existed in the 200-nm thick layer from the top surface were concentrated in the layer of 200–700nm depth from the surface. Additionally the oxygen content in the 200-nm thick layer decreased by the degassing as oxygen molecules from the glass surface, which is an essential requirement for the migration of Mg2+ and Ca2+ to cathode side. The bond scission between Si–O–Si is caused by the concentrated Mg2+ and Ca2+, resulting the formation of SiO−(Mg2+ or Ca2+)−OSi and Si· (Si E′ center). We have also confirmed the generation of oxygen hole center (NBOHC) and peroxy radical (POR) in the electrically poled soda-lime silicate glass.