Accelerated Crucible Rotation Technique ACRT

Three processes that are fast by comparison with bouyancy-driven convection and occur on acceleration/deceleration are - 

Afic = step change in rotation rate (rpm) = Afic x 27t/60 rads  

Spin-up/spin-down times should be Xi to maximize stirring. The number of spiral arms is given by  

15 (1988) 351, copyright (1988) reproduced with permission from The Minerals, Metals and Materials Society.) 

Bidirectional rotation is employed and rapid acceleration/deceleration (in 1-2 s) is easily achieved at any rotation rate. The Ekman layer thickness, d, from earlier flux growth, should be 0.05 cm, which necessitates rotation rates 20rpm. Horizontal and vertical flow velocities, V and W, are for all rotation rates, 

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Use of Forced Mixing via the Accelerated Crucible Rotation Technique (ACRT) in Bridgman Growth of Cadmium Mercury Telluride (CMT)... 

This chapter is split into 4 sections. The first deals briefly with purification of elemental mercury and tellurium, the second covers bulk growth of CMT by the Bridgman process and the third describes the addition of the accelerated crucible rotation technique (ACRT) to the basic Bridgman process. Finally, a few comments on the devices that have been and continue to be made from this material are given. 

Historically, the first technique used at SELEX Sensors and Airborne Systems Infrared Ltd. was the Bridgman process. Later, the emphasis switched to the accelerated crucible rotation technique (ACRT), a modification of the Bridgman process. Reviews of bulk growth can be found in [2,4]. 

Two-inch LGS single crystals were grown via the vertical Bridgman method assisted by the accelerated crucible rotation technique (ACRT) along [0001] (Z-axis), [211 0] (X-axis) and [0111] (54°-rotated Y-axis) for piezoelectric applications. 

Abbreviations used ACRT - Accelerated Crucible Rotation Technique, CZG - Czochralski Growth, EV Growth, HPS-High-pressure Solution Growth, HYG - Hydrothermal Growth, LPE-Liquid Phase Epitaxy. 

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