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TMA measurements of the viscous flow changes in glasses induced by illumination

Authors: Smolík Jan | Olmrová Zmrhalová Zuzana | Knotek Petr | Černošková Eva | Schwarz Jiří | Tichý Ladislav

Year: 2021

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	TMA measurements of the viscous flow changes in glasses induced by illumination	The viscous flow is important property of glassy materials that influences many processes (e.g. structural relaxations) and even the industrial applications (e.g. preparation of fibres) (Košťál, Shánělová, & Málek, 2020). The viscous flow can be influenced by photons with appropriate intensity and energy (e.g. in chalcogenides for example Se (Repka, Frumar, & Hrdlicka, 2007) or As2S3 (Tanaka, 2002)). This work is focused on the study of the viscous flow changes induced by different laser beams covering gap and sub-gap wavelengths (λ = 532, 650 nm) at various temperatures below the glass transition temperature (Tg) in the model bulk As2S3 glass (Egopt of As2S3  2.4 eV). The viscous flow and its photo-induced changes were measured by modified Thermomechanical analyzer using penetration method with optically transparent hemispherical indenter made from the optical quality silica glass (focusing of laser beam onto a sample). Changes of non-illuminated and illuminated viscous flow were compared. The illumination of samples led to the increasing of the viscous flow and thus to the changes of the penetration rate of the indenter into the sample. It was found that the laser emitting at λ = 650 nm (sub-gap photons) caused the higher photo-induced viscous flow changes due to the higher optical penetration depth leading to the larger light-affected volume of the glass. It was observed from cyclic measurements (illumination-dark-illumination) that the influence of photons on the viscous flow was only temporary - it vanished when laser was switched off and the viscous flow returned to its original state. Furthermore, the photo-induced viscous flow decreased with increasing temperature. The research was extended on the oxide glassy system PbO-ZnO-P2O5 modified by CoO. The role of photons, absorbed by different way (d-d transitions), on the viscous flow was studied as well.	viscous flow, thermomechanical analysis, penetration method, laser induced changes, glass