Title

X-ray diffraction study of NaF nano-crystals in photo-thermo-refractive glass

Authors

Authors

J. Lumeau; K. Chamma; L. Glebova;L. B. Glebov

Comments

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Abbreviated Journal Title

J. Non-Cryst. Solids

Keywords

Crystallization; XRD; Optical glass; Photosensitivity; Scattering; PHOTOTHERMOREFRACTIVE GLASS; CRYSTALLIZATION; INDEX; Materials Science, Ceramics; Materials Science, Multidisciplinary

Abstract

PTR glass is a photosensitive silicate glass which imparts refractive index change after UV-exposure and thermal development. The origin of photosensitivity is explained by the precipitation of NaF crystals inside the glass matrix. While nucleation of NaF in FIR glass has been thoroughly studied, the mechanisms of growth of NaF crystals have drawn a limited interest. To study the NaF growth, several techniques were combined: optical spectroscopy, interferometry, DSC and XRD. It was found that the size of NaF crystals in UV-exposed FIR glass, as determined by the broadening of the diffraction lines does not exceed similar to 20 nm. The NaF crystals' growth is limited by the exhaustion of Na+F- within the glass matrix as well as the increase of the viscosity of the glass surrounding the crystals that act as a kinetics barrier for further growth. X-ray diffraction analysis of NaF powder allowed calculating the crystals' volume fraction and their average size. A combination of these parameters with Rayleigh scattering model allowed the prediction of scattering at any wavelength and any thermal treatment, proving that scattering is determined by single crystals. (C) 2014 Elsevier B.V. All rights reserved.

Journal Title

Journal of Non-Crystalline Solids

Volume

405

Publication Date

1-1-2014

Document Type

Article

Language

English

First Page

188

Last Page

195

WOS Identifier

WOS:000347266400030

ISSN

0022-3093

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