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Femtosecond laser-induced transformations in ultra-low expansion glass: Microstructure and local density variations by vibrational spectroscopy

Efthimiopoulos I, Palles D, Richter S, Hoppe U, Moncke D, Wondraczek L, Nolte S, Kamitsos EI (2018)

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Publication Type: Journal article

Publication year: 2018

Journal

Book Volume: 123

Article Number: 233105

Journal Issue: 23

DOI: 10.1063/1.5030687

Abstract

We report X-ray diffraction, resonance Raman, and infrared (IR) results on pristine ultra-low expansion (ULE) glass, a binary titanosilicate glass with 5.67 mol. % TiO2. ULE processing by femtosecond (fs) laser radiation leads to nanograting writing and photo-darkening for imaging and data storage. We investigate here the vibrational/structural changes induced by fs laser irradiation of ULE at 515 nm. Optical imaging revealed the formation of micro-cavities, and Raman mapping showed molecular oxygen trapped in such cavities of laser-irradiated ULE glass. While titanium in the pristine glass was found predominantly in tetrahedral Ti⁴⁺ sites highly dispersed in the silicate matrix, Raman and IR reflectance spectroscopy on laser-irradiated ULE indicated the formation of Ti³⁺ sites; Ti³⁺ octahedral sites are formed in the shells of cavities and aggregate in amorphous Ti2O3-type clusters, while the glass around and below cavities contains Ti³⁺ tetrahedral sites dispersed in the silicate network. Laser-processed ULE glass was found to also exhibit local restructuring of the silicate matrix. Shifts of the strong IR band at about 1080-1100 cm^-1 were translated into changes of the average Si-O-Si bond angle in the laser-transformed areas and found to reflect local density variations; the average local density increases relative to silica glass up to about 8% in the shells of micro-cavities and decreases by about 0.5% in the surrounding material. Chemical processes were proposed to account for photo-darkening and the local structural transformation effect in the probed areas of the fs laser-processed ULE glasses.

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How to cite

APA:

Efthimiopoulos, I., Palles, D., Richter, S., Hoppe, U., Moncke, D., Wondraczek, L.,... Kamitsos, E.I. (2018). Femtosecond laser-induced transformations in ultra-low expansion glass: Microstructure and local density variations by vibrational spectroscopy. Journal of Applied Physics, 123(23). https://doi.org/10.1063/1.5030687

MLA:

Efthimiopoulos, Ilias, et al. "Femtosecond laser-induced transformations in ultra-low expansion glass: Microstructure and local density variations by vibrational spectroscopy." Journal of Applied Physics 123.23 (2018).

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