Non-stoichiometric crystallization of lithium metasilicate–calcium metasilicate glasses. Part 2 — Effect of the residual liquid

Fokin, Vladimir M.; Reis, Raphael M. C. V.; Abyzov, Alexander S.; Chinaglia, C.R.; Schmelzer, Jürn W. P.; Zanotto, Edgar Dutra

doi:10.1016/j.jnoncrysol.2013.08.006

Cited by 17 publications

(19 citation statements)

References 11 publications

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“…The segregation of SiO 2 phases during the crystallization of LS m was explained as a consequence of the lithium deficiency of the starting LS 2g composition . Similar considerations have been considered for different systems by Fokin et al At 7.7 GPa, heat treatment at 455°C and 500°C for nucleation and at 610°C for crystal growth induced the crystallization of LS m , with no evidences of the LS 2c crystalline phase. Fuss et al also observed the formation of LS 2c at 4.5 GPa and 608°C while, for samples processed at 6 GPa and 753°C, they observed the crystallization of a LS m solid solution.…”

Section: Introductionsupporting

confidence: 56%

Thermal stability of lithium metasilicate produced under high pressure from lithium disilicate glass

Buchner

Kulbieda

Fokin

et al. 2019

Int J of Appl Glass Sci

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Crystalline lithium disilicate, Li 2 Si 2 O 5 (LS 2c ) is usually produced at atmospheric pressure by suitable heat treatment of the glass with the same stoichiometric composition (LS 2g ). At this pressure, the orthorhombic phase of lithium disilicate is thermodynamically stable. The heat treatment of LS 2g under high pressure (7.7 GPa) induces the crystallization of lithium metasilicate Li 2 SiO 3 (LS m ) phase, which remains metastable after pressure release. In this work, distinct heat treatments under high pressure were chosen to produce lithium metasilicate crystals with different grain sizes embedded in the glass matrix: smaller than 10 µm, about 100 µm and larger than 100 µm. Thermal stability of this set of samples was investigated during subsequent heat treatments at atmospheric pressure. All samples were analyzed by X-ray diffraction, Raman spectroscopy and optical microscopy. Small LS m crystals produced under high pressure remained detectable only up to 1 hour of heat treatment at 610°C at atmospheric pressure while for longer heating times, the formation of quartz and crystalline LS 2c was observed. On the other hand, for the samples containing larger LS m crystals produced under high pressure, the metasilicate phase remained detectable up to 9.5 hours of subsequent heat treatment, forming spherulitic configurations. K E Y W O R D Sglass-ceramic, high pressure, lithium disilicate, lithium metasilicate, thermal stability

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Section: Introductionsupporting

confidence: 56%

Thermal stability of lithium metasilicate produced under high pressure from lithium disilicate glass

Buchner

Kulbieda

Fokin

et al. 2019

Int J of Appl Glass Sci

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“…This two stage crystallization process causes two distinct peaks in the DSC curve, which slightly overlap. More details on the crystallization of lithium ‐ calcium ‐ metasilicate glasses can be found elsewhere . As such, this glass deviates significantly from all of the model's assumptions.…”

Section: Methodsmentioning

confidence: 95%

“…and (a) do not end sharply after the peak maximum. This is a result of nonstoichiometric crystallization of this glass in the two following ways: The growth rate of the dendrites toward the sample interior starts with a constant linear rate and diminishes in the final stages of crystallization at a given temperature The formation of LS crystals also happens via “lateral” growth from the residual glass between the dendrites.…”

Section: Discussionmentioning

confidence: 99%

“…Surface crystallization of LS occurs with a dendritic morphology toward the sample interior. The rate of linear advancement of the dendrites is initially constant up to the final stages, when the growth starts to decelerate due to a significant change in the composition of the glass ahead of the crystallization front . Crystallization is eventually arrested due to the establishment of a metastable equilibrium between the residual glass enriched by calcium and the LS dendrites …”

Section: Methodsmentioning

confidence: 99%

“…When a certain temperature is reached, the residual glass phase rapidly and completely crystallizes into lithium metasilicate and calcium metasilicate . This two stage crystallization process causes two distinct peaks in the DSC curve, which slightly overlap.…”

Section: Methodsmentioning

confidence: 99%

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Determination of Crystal Growth Rates in Glasses Over a Temperature Range Using a Single DSC Run

2016

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In this work, we propose and test a simple and accurate technique capable of determining the crystal growth rate, U(T), over a fairly wide temperature range by means of a single differential scanning calorimetry run. This method is based on using 50-200 lm-thick samples with parallel rough surfaces so that crystal growth is effectively unidirectional and the crystallization fronts have a constant area during the entire crystallization process. Growth rates are calculated from the expression U(T) = LÁqÁDSC(T)/A peak , where DSC(T) is the value of the differential scanning calorimetry (DSC) crystallization curve at each temperature T, A peak is the overall peak area, L is half the sample thickness, and q is the heating rate. This method has been tested for different values of L and q for three glasses undergoing predominantly surface nucleation, that possess distinctly different crystallization behaviors: stoichiometric lithium disilicate and diopside (CaOÁMgOÁ2SiO 2 ) and a nonstoichiometric lithium-calcium metasilicate. Growth rates spanning temperature intervals of more than 100 K, including temperature ranges where literature data are scarce due to experimental difficulties, were determined using a single DSC run. The resulting U(T) data were compared with literature data obtained using optical microscopy. The growth rates determined using the proposed method show excellent agreement with the published data for both stoichiometric glasses and only small errors for the nonstoichiometric glass.

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Microstructure and mechanical properties of nucleant-free Li2O-CaO-SiO2 glass-ceramics

et al. 2017

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Non-stoichiometric crystallization of lithium metasilicate–calcium metasilicate glasses. Part 2 — Effect of the residual liquid

Cited by 17 publications

References 11 publications

Thermal stability of lithium metasilicate produced under high pressure from lithium disilicate glass

Thermal stability of lithium metasilicate produced under high pressure from lithium disilicate glass

Determination of Crystal Growth Rates in Glasses Over a Temperature Range Using a Single DSC Run

Microstructure and mechanical properties of nucleant-free Li2O-CaO-SiO2 glass-ceramics

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