The role of inner and internal radiation on the melt growth of sapphire crystal

Tavakoli, Mohammad Hossein; Abasi, Talaye Arjmand; Omid, Shirin; Mohammadi-Manesh, Ebrahim

doi:10.1002/crat.201200432

Cited by 9 publications

(5 citation statements)

References 28 publications

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“…The temperature and flow fields in the elements of a growth furnace result from the coupling of several heat transfer modes, namely, conduction in all furnace parts, convection in the melt and growth atmosphere, and radiation inside the semitransparent crystal and between the furnace elements. [16][17][18][19][20][21] Radiative heat transfer plays a key role in the growth process, and it acts directly on the temperature gradients and thermal stress in the crystal influencing then its quality.…”

Section: Introductionmentioning

confidence: 99%

Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li₂MoO₄ Bulk Crystal

Haddad

Bouzouaoui

Mokhtari

et al. 2022

Cryst. Res. Technol.

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Here, the radiative heat transfer inside a Czochralski furnace and the 3D thermal stress generated in a semitransparent Li2MoO4 crystal are deeply analyzed using anisotropic and temperature‐dependent elasticity and thermal expansion coefficients. The developed global numerical model takes into account induction heating, thermal conduction in all parts of the furnace, convection in the melt and the growth atmosphere, Marangoni convection at the free surface, radiation heat exchange between the furnace elements, internal radiation inside the semitransparent crystal and melt, and phase change at the growth interface. The contribution of each radiation mode is studied separately, then coupled together to clearly explain their roles in heat transfer, stress generation in the as‐grown crystal and in power consumption, and heat loss inside the furnace. Flow and temperature fields in the molten oxide and in the growth atmosphere as well as the thermal stress are presented and discussed for each case. Unrealistic cases are first considered where radiation exchange between the furnace elements and internal radiation in the assumed opaque crystal are neglected. For each case, the relation between temperature gradient and thermal stress is clearly demonstrated. Finally, the effect of the melt opacity on thermal stress is studied and related to temperature gradients in the crystal and at the free surface. The experimental observations are in good agreement.

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Section: Introductionmentioning

confidence: 99%

Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li₂MoO₄ Bulk Crystal

Haddad

Bouzouaoui

Mokhtari

et al. 2022

Cryst. Res. Technol.

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“…Several numerical works have been dedicated to the analysis of Cz growth of sapphire and other oxide crystals . The role of internal radiation in Cz growth of yttrium aluminium garnet and gadolinium gallium garnet was numerically investigated in [].…”

Section: Introductionmentioning

confidence: 99%

Modeling Interface Shape in Czochralski Growth of Sapphire Crystals

Stelian

Duffar

2017

Crystal Research and Technology

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Numerical modeling is applied to investigate the factors affecting the shape of the crystal-melt interface in Czochralski growth of sapphire crystals having 10 cm in diameter. The modeling is performed for a 2D -axisymmetric furnace configuration, where all the furnace components are included. The shape of the crystal-melt interface is computed by using the deformable mesh technique. Numerical results show that the conical shape of the interface depends essentially on the internal radiative heat exchanges in the semi-transparent sapphire crystal, being less influenced by the buoyancy convection. The Marangoni effect enhances the flow near the triple solid-liquid-gas point, leading to convex-concave shape of the growth interface, which is prone to facet formation. Numerically computed shape of the interface is compared to experimental results taken from literature. Applying crystal/crucible rotation has a significant impact on the flow pattern and the shape of the growth interface. Computations performed by applying only crystal rotation at rates higher than a critical value, show a reversed convection at the sample centre, underneath the crystal. This flow affects the shape of the interface, which is less curved and exhibits a convex shape. If the rotation rate is too much increased, the interface shape can be distorted by the intense flow. Application of crucible rotation intensifies the downward flow at the sample centre, leading to increased interface curvature. Rotating both the crystal and crucible in opposite directions generates a complex flow pattern, but has no flattening effect on the interface.

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“…Numerical Simulation of sapphire crystal growth in recent years mainly focused on the thermal field, flow field, stress field and the shape of the crystal-melt interface [4]. M.H.…”

Section: Introductionmentioning

confidence: 99%

“…M.H. Tavakoli et al [4] found inner and internal radiation within the growth furnace influence thermal field, heat transport structure and crystal-melt interface obviously. In the paper of H.S.…”

Section: Introductionmentioning

confidence: 99%

Effect of Marangoni convection by using computation simulation during the Kyropoulos sapphire crystal growth

Sun¹,

Gao²,

Gao³

et al. 2015

Proceedings of the First International Conference on Information Sciences, Machinery, Materials and Energy

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In the study, the effect of Marangoni convection is investigated on heat transport and melt-crystal interface during the Kyropoulos sapphire crystal growth by using the numerical simulation method. The presence of Marangoni convection increases the convexity of melt-crystal interface and causes the temporal concave of crystal during the shoulder turning stage. The clockwise vortex exposes near the triple point which leads to the beginning of remelting and Marangoni convection aggravates the remelting at the equal-diameter stage. During the last stage, Marangoni convection reinforces the main vortex near the free surface greatly and gives rise to the interface inversion,which brings about the cracking at the bottom of crystal. The numerical simulation results agree well with the experiment photo.

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The role of inner and internal radiation on the melt growth of sapphire crystal

Cited by 9 publications

References 28 publications

Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li₂MoO₄ Bulk Crystal

Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li₂MoO₄ Bulk Crystal

Modeling Interface Shape in Czochralski Growth of Sapphire Crystals

Effect of Marangoni convection by using computation simulation during the Kyropoulos sapphire crystal growth

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The role of inner and internal radiation on the melt growth of sapphire crystal

Cited by 9 publications

References 28 publications

Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li2MoO4 Bulk Crystal

Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li2MoO4 Bulk Crystal

Modeling Interface Shape in Czochralski Growth of Sapphire Crystals

Effect of Marangoni convection by using computation simulation during the Kyropoulos sapphire crystal growth

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Product

Resources

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Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li₂MoO₄ Bulk Crystal

Computational Analysis of Radiative Heat Transfer in Czochralski Furnace and 3D Anisotropic Thermal Stress in Li₂MoO₄ Bulk Crystal