Habit Changes of Sapphire Grown from PbO‐PbF2, and MoO3‐PbF2 Fluxes

Chase, A. B.; Osmer, Judith A.

doi:10.1111/j.1151-2916.1970.tb12121.x

Cited by 12 publications

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“…We chose this material as the model material in this study. Al 2 O 3 is known to grow into a variety of polyhedral shapes when grown with molybdenum trioxide (MoO 3 )-containing fluxes [18][19][20][21][22][23][24] and into plate-like shapes when grown with sulfuric acid-based fluxes. 25,26 Oxide additives are also known to change the crystal outline of Al 2 O 3 .…”

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confidence: 99%

Importance of raw material features for the prediction of flux growth of Al₂O₃ crystals using machine learning

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Section: Introductionmentioning

confidence: 99%

Importance of raw material features for the prediction of flux growth of Al₂O₃ crystals using machine learning

et al. 2022

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“…The equilibrium and theoretical growth forms of corundum are characterized by developed − {1012} planes. Synthetic corundum, however, generally develops {0001} planes and does not have developed − {1012} planes (e.g., Chase & Osmer 1970;Watanabe & Sumiyoshi 1977;Franke & Ghobarkar 1981).…”

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EVAPORATION AND CONDENSATION KINETICS OF CORUNDUM: THE ORIGIN OF THE 13μm FEATURE OF OXYGEN-RICH AGB STARS

Takigawa

Tachibana

Nagahara

et al. 2015

ApJS

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Corundum is predicted to be the most abundant refractory circumstellar dust and has been suggested as a candidate emitting the 13 μm feature in infrared spectra of oxygen-rich asymptotic giant branch stars. Crystalline dust has morphologies reflecting the anisotropic crystal structure and formation conditions or processesand may emit characteristic infrared features. In this study, evaporation and condensation experiments of corundum along different crystallographic orientations were performed in vacuum to determine key kinetic parameters controlling morphological anisotropy: evaporation and condensation coefficients (α e and α c ), the degrees of kinetic hindrance on evaporation and condensation. Plausible shapes of corundum condensates were estimated from the experimental results to evaluate the infrared features of corundum condensates. The evaporation coefficients of corundum are 0.02-0.2 at 1600-1785°C, which increase with temperature and show notable anisotropy. The order of α e along the crystallographic c, a, and maxes is α e m ≫ α e a > α e c irrespective of temperature. The obtained condensation coefficients along the c, a, and maxes at 1575°C and a supersaturation ratio of ∼4 are 0.04-0.06, 0.06-0.08, and 0.1-0.2, respectively. The morphology of condensed circumstellar corundum expected from our experiments is oblate and slightly flattened to the caxisand is consistent with the fact that no presolar corundum with eccentric shapes has been found. The mass absorption coefficient of oblate corundum slightly flattened to the caxis shows a peak at 13 μm without any accompanying strong peaks. These results strongly indicate that corundum condensed anisotropically in circumstellar environments is a carrier of the unidentified 13 μm feature around oxygen-rich evolved stars.

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Contribution to the habit of hydrothermally grown corundum

Franke¹,

Ghobarkar²

1981

Cryst Res and Technol

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Dedicated to Professor Georg MANECKE on the occasion of his 66th birthdayThe growth of corundum crystals without the influence of extraneous ions was achieved by the treatment of single crystals of topaz with supercritical water. The result is in agreement with previous calculations and considerations of other authors. A review of the different indexation of the corundum lattice is given.Korundkristalle wurden durch Behandlung von Topas-Einkristallen mit uberkritischem Wasser erhalten. Die Ergebnisse bestatigen die Berechnungen und theoretischen ttberlegungen anderer Autoren. Zusatzlich wird ein merblick uber die verschiedenen Arten der Aufstellung und Indizierung des Korundgitters gegeben.

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Habit Changes of Sapphire Grown from PbO‐PbF₂, and MoO₃‐PbF₂ Fluxes

Cited by 12 publications

References 9 publications

Importance of raw material features for the prediction of flux growth of Al₂O₃ crystals using machine learning

Importance of raw material features for the prediction of flux growth of Al₂O₃ crystals using machine learning

EVAPORATION AND CONDENSATION KINETICS OF CORUNDUM: THE ORIGIN OF THE 13μm FEATURE OF OXYGEN-RICH AGB STARS

Contribution to the habit of hydrothermally grown corundum

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Habit Changes of Sapphire Grown from PbO‐PbF2, and MoO3‐PbF2 Fluxes

Cited by 12 publications

References 9 publications

Importance of raw material features for the prediction of flux growth of Al2O3 crystals using machine learning

Importance of raw material features for the prediction of flux growth of Al2O3 crystals using machine learning

EVAPORATION AND CONDENSATION KINETICS OF CORUNDUM: THE ORIGIN OF THE 13μm FEATURE OF OXYGEN-RICH AGB STARS

Contribution to the habit of hydrothermally grown corundum

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Habit Changes of Sapphire Grown from PbO‐PbF₂, and MoO₃‐PbF₂ Fluxes

Importance of raw material features for the prediction of flux growth of Al₂O₃ crystals using machine learning

Importance of raw material features for the prediction of flux growth of Al₂O₃ crystals using machine learning