Phase Transformations in Glass of the MgOAl₂O₃SiO₂TiO₂
System Doped with Yttrium Oxide

I. P. Alekseeva^a, O. S. Dymshits^a, A. A. Zhilin^a, M. D. Mikhailov^a, and A. A. Khubetsov^a,b

^a Research and Technological Institute of Optical Materials All-Russia Scientific Center Vavilov State Optical Institute,
ul. Babushkina 36/1, St. Petersburg, 192171 Russia

^bPetr Velikii St. Petersburg Polytechnical University, ul. Politekhnicheskaya 29, St. Petersburg, 195251 Russia

e-mail: khubezov@gmail.com

Received February 10, 2015

Abstract—Phase transformations upon crystallization of glasses in a magnesium-aluminosilicate system nucleated
with TiO₂ as a nucleating agent, both doped and undoped with yttrium oxide, which were thermally treated in single-
and two-stage modes in the temperature range 750–1200C, have been investigated. Use of the two-stage mode with
the first stage (nucleation) at 750C yields changes in the phase composition and the temperature range of the exist-
ence of the metastable crystalline phases formed within the 800–1000C range. At the highest thermal treatment tem-
perature (1200C), one observes crystallization of phases that are stable ones for this particular glass composition,
irrespective of the existence of the nucleation stage. Doping with Y₂O₃ significantly affects the character of liquid
phase separation and crystallization through the increase of the temperature of formation of the first crystalline
phases. There appear yttrium-containing phases— yttrium disilicate and titanate. The mechanism of the effect of
yttrium oxide on the phase separation processes has been suggested.

DOI: 10.1134/S1087659615060024

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