Control of growth interface shape using vibroconvective stirring applied to vertical Bridgman growth

• Published in: Journal of crystal growth Vol. 282; no. 1; pp. 236 - 250
• Main Authors: Zawilski, Kevin T., Custodio, M. Claudia C., DeMattei, Robert C., Feigelson, Robert S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.08.2005; Elsevier
• Subjects: A1. Convection; A1. Directional solidification; A1. Fluid flows; A1. Stirring; A2. Bridgman technique; B1. Oxides; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical and elastic waves, vibrations; Methods of crystal growth; physics of crystal growth; Physics; A2. Bridgman technique; A1. Stirring; B1. Oxides; A1. Directional solidification; A1. Convection; A1. Fluid flows; Fluctuations; Inorganic compounds; Growth rate; Lead titanates; Stirring; Growth interface; Transition element compounds; Surfaces; Vibrations; Flow(fluid); Growth mechanism; Test method; Control method; Lead Niobates; Rate constant; Bridgman method
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2005.04.084

The ability of vibroconvective stirring to control the growth interface shape during vertical Bridgman growth was demonstrated using the coupled vibrational stirring (CVS) technique. CVS involves the application of low-frequency vibrations to the outside of the growth ampoule and produces strong flows emanating from the fluid surface. Previous studies showed that the growth rate and interface shape fluctuations occurred under growth with a constant vibrational frequency. In order to eliminate these fluctuations, this paper examines methods to lower the vibrational frequency as growth progressed to maintain a constant fluid flow rate in the vicinity of the growth interface. These flow control methods were tested on two growth systems: NaNO 3 and lead magnesium niobate–lead titanate (PMNT). The previously observed fluctuations were greatly reduced when flows were appropriately controlled. Using this control method, CVS flows were then applied to reduce the concavity of the growth interface in the NaNO 3 system at fast growth rates (>10 mm/h).