Metastable solid solutions with quartz-type structures on the join SiO2–MgAl2O4

Schreyer, Werner; Schairer, J. F.

doi:10.1524/zkri.1961.116.1-2.60

Cited by 150 publications

(56 citation statements)

References 7 publications

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“…It is known that l-cordierite is a metastable phase [24] and thus exact values of the heat of melting DH v and melting point T m are not available. Therefore, the following limiting values were taken from [25,26]: …”

Section: Crystal Nucleation Rates-homogeneous Nucleationmentioning

confidence: 99%

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Surface and volume nucleation and growth in TiO2–cordierite glasses

Fokin

Zanotto

1999

Journal of Non-Crystalline Solids

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Systematic measurements and analyses of surface nucleation and growth of l-cordierite on diamond-polished surfaces and on fractured surfaces of cordierite glasses containing 0.3, 1.2, 3.4, 6.2 and 8.1 wt% TiO 2 were carried out. All the glasses exhibit surface nucleation, however, the glass having 8.1 wt% TiO 2 also exhibits volume nucleation. The maximum surface nucleation rate is located at a temperature considerably higher than the maximum volume nucleation rate. Both surface and volume crystallization occur by heterogeneous nucleation. The average nucleus/substrate wetting angles, h, were estimated from surface and volume nucleation measurements. The widely dierent values of h indicate that the active catalyzing sites are dierent for surface and volume crystallization. It is likely that Al 2 TiO 5 crystals induce volume crystallization of l-cordierite, while surface crystallization is aected by TiO 2 , defects and relicts of polishing power. Nucleation on fractured surfaces was induced mainly by solid particles, most likely by broken glass particles. The crystal growth velocity of l-cordierite crystals is well ®tted by the 2D-surface nucleation growth model. Ó

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Section: Crystal Nucleation Rates-homogeneous Nucleationmentioning

confidence: 99%

“…(23a), (24) and (24a)). Table 6 lists the surface free energy values for the cases of`small' and`large' crystal, calculated from the plots of Fig.…”

Section: The Bidimensional (Secondary) Surface Nucleation Growth Modelmentioning

confidence: 99%

Surface and volume nucleation and growth in TiO2–cordierite glasses

Fokin

Zanotto

1999

Journal of Non-Crystalline Solids

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“…BROVETTO (1), V. MAXIA(1), M. SALIS (1), G. SPANO (1) i. DELMASTRO (2), D. MAZZA (2) and M. VALLINO (2) (1) Gruppo Nazionale Struttura della Materia -Cagliari Point defects in ionic crystals originate localized charges which, when crystals are excited by ionizing radiations at low temperature, trap opposite-sign carriers. The thermoluminescent (TL) emission which ensues when carriers are released from traps at high temperature yields information on this kind of defects.…”

Section: Investigation Of Cordierite Lattice Defects By Thermoluminesmentioning

confidence: 99%

Investigation of cordierite lattice defects by thermoluminescence experiments

Brovetto¹,

Maxia²,

Salis³

et al. 1992

Nouv Cim D

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Point defects in ionic crystals originate localized charges which, when crystals are excited by ionizing radiations at low temperature, trap opposite-sign carriers. The thermoluminescent (TL) emission which ensues when carriers are released from traps at high temperature yields information on this kind of defects.By TL experiments we investigated samples of ~-and a-cordierite, which is a magnesium alumino-silicate characterized by the presence of ring-shaped anionic radicals similar to the Si6 01s ring radicals of beryl structure. The easy exchange of Si and A1 ions in oxygen tetrahedra, which is peculiar to these compounds, is expected to originate point charges detectable by recording the TL emission. -Experiments.Samples having composition Mg2A14 Si 5 018 were prepared by a solgel route. An aqueous solution of aluminum and magnesium nitrates in proper amounts was added to the stoichiometric quantity of tetraethylorthosilicate (TEOS), adjusting the resultant pH to 1.5 with HNOs. On raising temperature to 80~ while stirring, TEOS slowly hydrolizes and dissolves into the solution of the two nitrates. Thus a clear solution is obtained, which is gelled by rapid addition of excess aqueous ammonia solution. The basic (pH = 10) gel obtained is then gradually heated up to 400 ~ thus 657

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“…This consists in the formation of domains whose chemical composition and ordering in the arrange. When glasses from the system SiO 2-A1203-MgO are crystallized, a solid solution having the structure of high-temperature quartz is formed first [12], which is similar to that resulting from the rearrangement of the structure of montmorilionite. At higher temperatures, its chemical composition is changed and it passes into corderite, Mg2AI3[A1SisOla], an equilibrium crystal phase in this system, It can be seen that the mechanisms of intraframework reactions of new crystal phase formation from X-ray amorphous products of dehydroxylation of layer silicates and glasses reveal great similarities, in spite of the quite different parent substances.…”

Section: Reaction Of Framework Rebuildingmentioning

confidence: 96%

Intraframework thermal reactions of solids

Stoch

1987

Journal of Thermal Analysis

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Metastable solid solutions with quartz-type structures on the join SiO₂–MgAl₂O₄

Cited by 150 publications

References 7 publications

Surface and volume nucleation and growth in TiO2–cordierite glasses

Surface and volume nucleation and growth in TiO2–cordierite glasses

Investigation of cordierite lattice defects by thermoluminescence experiments

Intraframework thermal reactions of solids

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