Verneuil Crystal Growth in the Arc-Image Furnace

The aim of this study was to obtain synthetic corundum monocrystals, called star ruby and star sapphire, using the Verneuil flame fusion process. The corundum monocrystals are known to possess an unusual complex of properties which determine their increasing application in different areas of jewelry and technology The optimal temperature-time parameters during obtaining the starting mixtures which contribute to the synthesis of high quality corundum monocrystals were established. The corundum monocrystals obtained are equivalent to the natural gemstones -rubies and sapphires.

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“…Using the Verneuil flame fusion process [7,8], ruby, sapphire and leicosapphire were obtained (see Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

Titanium Containing Monocrystals of Ruby and Sapphire

et al. 2011

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“…The natural non-circular shape of the faceting is indicated for such a crystal. This effect could be clearly observed for incongruently melted compounds, and in some cases, the obtaining of perfect crystals is very problematic, for example, for Y 3 This effect is due to little nonuniformity of the strict circular symmetry of the melting zone under heating. The minor temperature modulation on the periphery of the growth interface at the crystal rotation leads to fast local crystallization near the crystal surface.…”

Section: Rotation Effectmentioning

confidence: 99%

“…Many optical schemes with concentrators for these purposes have been proposed (Figure 1). Crystal growth of refractory oxides by the floating zone technique was introduced by Halden [3], O'Bryan [4], Fairholme [5], Field and Wagner [6], and Medvedev and Balbashov [7]. Employed bi-ellipsoidal and bi-paraboloidal apparatus arrangements used a carbon arc or short arc xenon lamp as radiation sources.…”

Section: Introductionmentioning

confidence: 99%

Contemporary Apparatus for Single Crystals Growth of Oxide Compounds and Metals by Optical Floating Zone (FZ)

Balbashov

2019

Crystals

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A contemporary apparatus with radiation (light) heating for growth of single crystals of refractory oxides and metals is described. To reduce the dissociation or evaporation of the melt or crystal components, the growth process was carried out in oxygen or an alternative gas at pressures up to 100 bar. The annealing system applied directly in the growth process at 1650 °C under O2 pressure and at temperatures up to 2500 °C under protective gas flow, allows the obtaining of large and perfect single crystals. Many single crystals of oxide materials, including incongruently melting substances, such as Y3Fe5O12, Gd3Fe5O12, BaFe12O19, SrFe12O19, BaFe12-x AlxO19, and many others have been grown, and much more could be grown.

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“…-Universellement utilisée depuis plus d'un demi-siècle pour les besoins de la joaillerie et de l'horlogerie, cette technique, appliquée de manière assez rudimentaire jusqu'à ces dernières années, a été étudiée avec un intérêt nouveau et s'est vue sensiblement modifiée et perfectionnée [3] lorsque le laser a nécessité des cristaux de qualité améliorée; plusieurs modes de chauffage ont été proposés en remplacement du chalumeau oxhydrique, trop brutal et difficile à stabiliser pour une longue durée : four à image [4], torche à plasma [5], sans qu'il soit possible néanmoins d'éviter ou d'éliminer ultérieurement de façon satisfaisante les tensions d'origine thermique et les désorientations réticulaires qui caractérisent généralement les rubis élaborés par ce procédé; de plus, ces derniers ne peuvent en pratique croître que dans une seule direction cristallographique : celle où l'axe optique est à environ 600 de l'axe géométrique du cristal.…”

unclassified

Cristallogénèse du rubis par zone flottante dans un four à résistance

Du¹,

Aubrée²

1967

Rev. Phys. Appl. (Paris)

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2014 On décrit un appareillage et un procédé de fabrication de monocristaux de rubis, utilisant la technique de la zone flottante par chauffage à résistance sous atmosphère d'argon. Des monocristaux de forme cylindrique 6 x 60 mm, avec une concentration en Cr3+ de 500 ppm, d'orientation [0001], ont été obtenus. La vitesse de croissance est de 14 mm/h. Les densités moyennes de dislocations sont inférieures à 104 cm-2. L'effet laser a été observé sur les cristaux réalisés par cette méthode. Abstract. 2014 Apparatus and process for growing ruby single-crystals, using the floating zone technique by resistance heating under an argon atmosphere, are described. Cylindrical 6 x 60 mm single-crystals, with a 500 ppm Cr3+ concentration, [0001]-axis orientation, were obtained. Growth rate was 14 mm/h. Average dislocation densities were less than 104 cm-2. The laser effect was observed on the crystals grown by this method.

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Verneuil Crystal Growth in the Arc-Image Furnace

Abstract: The development of an arc-image system for crystal growth, and techniques for obtaining continuous growth of single crystals under controlled atmospheres, are described. Crystals grown include rutile, sapphire, ruby, stabilized zirconia, and ferrites.

Cited by 13 publications

References 3 publications

Titanium Containing Monocrystals of Ruby and Sapphire

Titanium Containing Monocrystals of Ruby and Sapphire

Contemporary Apparatus for Single Crystals Growth of Oxide Compounds and Metals by Optical Floating Zone (FZ)

Cristallogénèse du rubis par zone flottante dans un four à résistance

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