Volume, index-of-refraction, and stress changes in electron-irradiated vitreous silica

Abstract

The volume, index-of-refraction, and stress changes induced in vitreous silica by irradiating with 18-keV electrons have been measured over the dose range from 2.5×1010 to 3×1012 rad. The volume and index measurements were performed using a new technique based on producing a spatial modulation of irradiated and unirradiated areas which is used as an optical phase grating. Comparison of the volume change and stress measurements shows there are two components to the compaction; one component, which dominates below doses of 2×1011 rad, is associated with stress generation, while the other component, which dominates at higher doses, proceeds without generating stress. In addition, the relationship between the index change and volume change observed for electron irradiation is different from that obtained by neutron irradiation and hydrostatic compression. The index-vs-volume change data can be interpreted using the Lorentz-Lorenz formalism and Neuman strain-optical constants, and provides further evidence of the two different compaction processes. The measured stress saturates at 1.5×108 N/m2 at approximately 6×1011 rad (0.24% volume change) and decreases with subsequent irradiation. In contrast the volume and index changes saturate at approximately 2×1012 rad (1.4% volume change).

A Novel Approach for Preparation and In Situ Tensile Testing of Silica Glass Membranes in the Transmission Electron Microscope

“…Moreover, structural changes and changes in the mechanical properties of vitreous silica (Primak and Kampwirth, 1968;Dellin et al, 1977;Storm et al, 2005) and silica glass (Yamaguchi et al, 2004;Iwata and Nishi, 2008) are reported upon irradiation with electrons on the macroscopic and microscopic scale. To account for this, we carried out a systematic analysis of the impact of Ga + irradiation (during FIB preparation) and e-beam irradiation (during experiments in the TEM) on the structure of silica glass membranes.…”

“…The high energy e-beam generates structural and bonding defects and facilitates the bond-switching mechanism, which favors the rotation and migration of atomic clusters to accommodate plastic flow in the amorphous network (Zheng et al, 2010). However, high energy e-beam irradiation can also result in structural changes, such as densification in case of vitreous silica (Primak and Kampwirth, 1968;Dellin et al, 1977) and local deformations in case of amorphous silica films (Storm et al, 2005). These examples altogether indicate that under certain circumstances the conventionally brittle silica glass in general can exhibit enormous ductility and/ or superplasticity.…”

Density of vitreous silica

“…More recent work deals primarily with the opposing radiation-induced compaction [10][11][12][13][14] of as-received vitreous silicas and the radiation-induced expansion of these glasses when they contain high concentrations of dissolved hydrogen [10,15]. Radiation-induced expansion is accompanied by the formation of large quantities of bound hydrogen species [10,15].…”

Nanoscale morphologies resulting from surface treatments of display glass in vacuum

“…Like ion or neutron irradiation, electron-beam irradiation can also cause the densification of silica [24,29]. The energy deposition from electrons mainly results in ionization and not direct collisions, so the rate of densification should not be as high as for ions.…”