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

    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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