Visualization of Spatial Charge in Thermally Poled Glasses via Nanoparticles Formation

Abstract

It is shown for the first time that the vacuum poling of soda-lime silicate glass and the subsequent processing of the glass in a melt containing silver ions results in the formation of silver nanoparticles buried in the subanodic region of the glass at a depth of 800–1700 nm. We associate the formation of nanoparticles with the transfer of electrons from negatively charged non-bridging oxygen atoms to silver ions, their reduction as well as their clustering. The nanoparticles do not form in the ion-depleted area just beneath the glass surface, which indicates the absence of a spatial charge (negatively charged oxygen atoms) in this region of the vacuum-poled glass. In consequence, the neutralization of the glass via switching of non-bridging oxygen bonds to bridging ones, which leads to the release of oxygen, should occur in parallel with the shift of calcium, magnesium, and sodium ions into the depth of the glass.

Glass poling as a substrate surface pre-treatment for in situ metal nanoparticle formation by reduction of metal salt

“…This indicates lack of Ag in coating over both, step and poled region suggesting that Ag has diffused into glass regardless to poling. This is in accordance with another study where is shown that Ag + from hot salt melt bath enter into vacuum poled glass and form NPs there [32]. In our case NPs in glass were not observed after coating removal.…”