Title

Liquid-Liquid Phase Separation in Photo-Thermo-Refractive Glass

Authors

Authors

G. P. Souza; V. M. Fokin; C. F. Rodrigues; A. C. M. Rodrigues; E. D. Zanotto; J. Lumeau; L. Glebova;L. B. Glebov

Comments

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Abbreviated Journal Title

J. Am. Ceram. Soc.

Keywords

SILICATE; CRYSTALLIZATION; KINETICS; Materials Science, Ceramics

Abstract

Photo-thermo-refractive (PTR) glass is an optical Na-Al-Zn-K-O-F-Br silicate glass doped with Ag, Ce, Sb, and Sn that undergoes photo-thermo-induced volume crystallization of nanosized NaF responsible for localized refractive index changes. PTR glass has found numerous commercial applications, but the intricate mechanism of photo-thermo crystallization is far from being understood. In this paper, we demonstrate that, additional to crystalline phase precipitation, liquid-liquid phase separation (LLPS), i.e. amorphous droplets embedded in the matrix glass, appears concurrently over a wide range of temperatures. The immiscibility temperature is 925 degrees C. The droplet phase is richer in SiO(2), rendering the alkali-rich remaining matrix glass a lower glass transition temperature and a higher electrical conductivity than the original glass. The droplet's surface does not catalyze NaF nucleation. Although the effects of LLPS on optical properties of PTR glass are still to be explored, it could contribute to unwanted scattering losses and/or uncontrolled refractive index change. The substantial change in the original glass composition resulting from LLPS should play an important role on NaF crystallization kinetics, and therefore must be considered for an overall understanding of the crystallization mechanism underpinning the refractive index change in PTR glass.

Journal Title

Journal of the American Ceramic Society

Volume

94

Issue/Number

1

Publication Date

1-1-2011

Document Type

Article

Language

English

First Page

86

Last Page

91

WOS Identifier

WOS:000285972100013

ISSN

0002-7820

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