Growth of the world's largest sapphire crystals

Khattak, C. P.; Schmid, F.

doi:10.1016/s0022-0248(01)00955-1

Cited by 64 publications

(35 citation statements)

References 17 publications

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“…The ability to engineer three significantly different microstructures from the same starting material is also technologically very advantageous. Each microstructure class provides useful properties: single crystal sapphire can be used for high strength armor windows [18] or substrates for LED applications [19], a bimodal microstructure in many materials can enhance toughness as compared to a microstructure with a unimodal grain size distribution [20], and ultra-fine grain alumina can have higher strength and ductility as compared to coarse-grained alumina [21].…”

Section: Opportunitiesmentioning

confidence: 99%

Complexion time-temperature-transformation (TTT) diagrams: Opportunities and challenges

Schumacher

Marvel

Kelly

et al. 2016

Current Opinion in Solid State and Materials Science

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a b s t r a c tGrain boundaries and other interfaces can undergo complexion transitions from one thermodynamic state to another, resulting in discontinuous changes in interface properties such as diffusivity, mobility, and cohesive strength. The kinetics of such complexion transitions has been largely overlooked until recently. Just as with bulk phase transformations, complexion transition kinetics can be represented on time-temperature-transformation (TTT) diagrams. An experimental complexion TTT diagram is presented here for polycrystalline Eu-doped spinel annealed at 1400-1800°C. This material developed a microstructure with a bimodal grain size distribution, indicating that a complexion transition occurs within this temperature range. The time and temperature dependence of this complexion transition was analyzed and used to produce a grain-boundary complexion TTT diagram for this system. Complexion TTT diagrams have the potential to be remarkably useful tools for manipulating the properties of internal interfaces in polycrystalline metals and ceramics. The development of experimental complexion TTT diagrams is likely to have an important impact on the field of grain-boundary engineering, and hence the development of these experimental diagrams should be an intense area of focus in the coming years.

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Section: Opportunitiesmentioning

confidence: 99%

Complexion time-temperature-transformation (TTT) diagrams: Opportunities and challenges

Schumacher

Marvel

Kelly

et al. 2016

Current Opinion in Solid State and Materials Science

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“…2(a) also shows the charging processes of the raw materials and the seed crystal. The raw materials, blocks of sintered alpha-alumina with a density of about 3.5 g/cm 3 , are put into the crucible from above as shown in Fig. 2(a).…”

Section: Methodsmentioning

confidence: 99%

“…The Kyropoulos (KP) method [1,2], the heat exchange (HE) method [1,3], the edge-defined, film-fed growth (EFG) method [1,4], and the Czochralski (CZ) method [1,5] are well known and important techniques for growing large high-quality sapphire crystals.…”

Section: Introductionmentioning

confidence: 99%

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Vertical Bridgman growth of sapphire crystals, with thin-neck formation process

Hoshikawa

Taishi

Ohba

et al. 2014

Journal of Crystal Growth

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“…This was so because the present VB method provides no mechanism to prevent the melting of the seed crystal, such as the He-gas cooling in the HE method [3,4].…”

Section: Temperature Measurement and Seeding Processmentioning

confidence: 99%

Vertical Bridgman growth of sapphire—Seed crystal shapes and seeding characteristics

Hoshikawa

Osada

Saitou

et al. 2014

Journal of Crystal Growth

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The growth of sapphire by the traditional vertical Bridgman (VB) method was studied by using various shapes of seed crystals and tungsten (W) crucibles shaped to match the seeds. Approximately 2-inch diameter, c-axis sapphire single crystals were reproducibly grown from three kinds of seed: thin, tapered and full diameter. Factors relating seed type to single-crystal growth are discussed, including the reproducibility of seeding processes, and the generation and elimination of low-angle grain boundaries (LAGBs). What was learned facilitated the subsequent growth of large-diameter, 3-, 4-and 6-inch, c-axis single-crystal sapphires from full-diameter seeds.

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Growth of the world's largest sapphire crystals

Cited by 64 publications

References 17 publications

Complexion time-temperature-transformation (TTT) diagrams: Opportunities and challenges

Complexion time-temperature-transformation (TTT) diagrams: Opportunities and challenges

Vertical Bridgman growth of sapphire crystals, with thin-neck formation process

Vertical Bridgman growth of sapphire—Seed crystal shapes and seeding characteristics

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