Phase separation and crystallization in glasses of the lithium silicate system xLiO · (100 − x)SiO ( x = 23.4, 26.0, 33.5).

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Title:	Phase separation and crystallization in glasses of the lithium silicate system xLiO · (100 − x)SiO ( x = 23.4, 26.0, 33.5).
Authors:	Sycheva, G. A.¹ Sycheva_galina@mail.ru
Source:	Glass Physics & Chemistry. Apr2011, Vol. 37 Issue 2, p135-149. 15p. 3 Black and White Photographs, 3 Charts, 6 Graphs.
Subjects:	Phase separation method (Engineering), Crystallization, Lithium silicates, Lithium, Crystal growth
Abstract:	The phase separation in ultimately homogenized glasses of the lithium silicate system xLiO · (100 − x)SiO (where x = 23.4, 26.0, and 33.5 mol % LiO) has been investigated. The glasses of these compositions have been homogenized using the previously established special temperature-time conditions, which provide the maximum dehydration and the removal of bubbles from the glass melt. The parameters of nucleation and growth of phase_separated inhomogeneities and homogeneous crystal nucleation have been determined. The absolute values of the stationary nucleation rates I of lithium disilicate crystals in the 23.4LiO · 76.6SiO and 26LiO · 74SiO glasses with the compositions lying in the metastable phase separation region have been compared with the corresponding rates I for the glass of the stoichiometric lithium disilicate composition. It has been established that the crystal growth rate have a tendency toward a monotonic increase with an increase in the temperature, whereas the dependences of the crystal growth rate on the time of low-temperature heat treatment exhibit an oscillatory behavior with a monotonic decrease in the absolute value of oscillations. The character of crystallization in glasses with the compositions lying in the phase separation region of the LiO-SiO system is compared with that in the glass of the stoichiometric lithium disilicate composition. The inference has been made that the phase separation weakly affects the nucleation parameters of lithium disilicate and has a strong effect on the crystal growth. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

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Abstract:	The phase separation in ultimately homogenized glasses of the lithium silicate system xLiO · (100 − x)SiO (where x = 23.4, 26.0, and 33.5 mol % LiO) has been investigated. The glasses of these compositions have been homogenized using the previously established special temperature-time conditions, which provide the maximum dehydration and the removal of bubbles from the glass melt. The parameters of nucleation and growth of phase_separated inhomogeneities and homogeneous crystal nucleation have been determined. The absolute values of the stationary nucleation rates I of lithium disilicate crystals in the 23.4LiO · 76.6SiO and 26LiO · 74SiO glasses with the compositions lying in the metastable phase separation region have been compared with the corresponding rates I for the glass of the stoichiometric lithium disilicate composition. It has been established that the crystal growth rate have a tendency toward a monotonic increase with an increase in the temperature, whereas the dependences of the crystal growth rate on the time of low-temperature heat treatment exhibit an oscillatory behavior with a monotonic decrease in the absolute value of oscillations. The character of crystallization in glasses with the compositions lying in the phase separation region of the LiO-SiO system is compared with that in the glass of the stoichiometric lithium disilicate composition. The inference has been made that the phase separation weakly affects the nucleation parameters of lithium disilicate and has a strong effect on the crystal growth. [ABSTRACT FROM AUTHOR]
ISSN:	10876596
DOI:	10.1134/S1087659611020155