Micro-pulling-down

The micro-pulling-down (μ-PD) method is a crystal growth technique based on continuous transport of the melted substance through micro-channel(s) made in a crucible bottom. Continuous solidification of the melt is progressed on a liquid/solid interface positioned under the crucible. In a steady state, both the melt and the crystal are pulled-down with a constant (but generally different) velocity.

Crystallization
Fundamentals
Crystal · Crystal structure · Nucleation
Concepts
Crystallization · Crystal growth Recrystallization · Seed crystal Protocrystalline · Single crystal
Methods and technology
Boules Bridgman–Stockbarger method Crystal bar process Czochralski method Epitaxy · Flux method Fractional crystallization Fractional freezing Hydrothermal synthesis Kyropoulos method Laser-heated pedestal growth Micro-pulling-down Shaping processes in crystal growth Skull crucible Verneuil method Zone melting

Many different types of crystal are grown by this technique, including Y₃Al₅O₁₂, Si, Si-Ge, LiNbO₃, α-Al₂O₃, Y₂O₃, Sc₂O₃, LiF, CaF₂, BaF₂, etc.[1][2]

Crystal growth routine

Standard routine procedure used in the growth of most of μ-PD crystals is well developed. The general stages of the growths include:

• Charging of the crucible with starting materials (mixture of powders)
• Heating of the crucible until starting materials in the crucible are completely melted
• Upward displacement of the seed until its contact with the meniscus or crucible
• Formation of the meniscus and partial melting of the seed top
• Correction of the shape of the meniscus through appropriate adjustment of crucible temperature and position of the seed crystal
• Crystal growth through pulling of the seed in downward direction
• Separation of the as grown crystal from the meniscus
• Cooling of the system (including the crystal and the crucible) to room temperature

See also

• Crystal growth
• Czochralski process
• Float-zone silicon
• Flux method
• Laser-heated pedestal growth
• Shaping processes in crystal growth
• Verneuil process

• Lithium niobate
• Sapphire
• Scandium(III) oxide
• Yttrium aluminium garnet

References

1. Fukuda, Tsuguo; Chani, Valery I (2007). T. Fukuda; V.I. Chani (eds.). Shaped Crystals: Growth by Micro-Pulling-Down Technique. Berlin: Springer-Verlag. ISBN 978-3-540-71294-7.
2. Yoshikawa, A.; Nikl, M.; Boulon, G.; Fukuda, T. (2007). "Challenge and study for developing of novel single crystalline optical materials using micro-pulling-down method". Opt. Mater. 30 (1): 6–10. Bibcode:2007OptMa..30....6Y. doi:10.1016/j.optmat.2006.10.030.