Simulation of non-axisymmetric floating zone crystal growth under microgravity

Abstract

The possibility of growing crystals of non-circular cross-section by using the floating zone technique is considered, basing the analysis on the isothermal liquid bridge model, and restricting the study to a linear asymptotic analysis. An almost square initial seed is considered in more detail, although the analysis is general and can be applied to other initial shapes, not only of the seed but also of the supply rod, that can be of any cross-section. The influence of non-circular seed and/or feed cross-section shape, and of a possible axial acceleration typical of microgravity platforms (sounding rockets and space labs), on both the liquid interface shape and the solid grown shape, are analysed, including the stability limits by breaking of the molten bridge.

Analytical modelling of floating zone crystal growth

“…This behaviour is seen in the phase diagram for Eq. (12), shown in These analytical results compare very well qualitatively to the non-linear numerical simulation developed in Martinez, Meseguer and Perales (2001) that is shown below (Figures 3 to 5) to place the analytical results in a better context. …”

Stability of liquid bridges between an elliptical and a circular supporting disk

“…The influence of different perturbations on the stability of liquid bridges have been extensively analyzed from both the theoretical and the experimental point of view. However, leaving apart nonmechanical disturbances, except in a few papers very recently published ͑two of them dealing with the equilibrium interface shapes of liquid bridges between noncircular supports, 11,12 and a third dealing with the asymptotic stability of long liquid bridges between noncircular disks 13 ͒, to our knowledge all published works to date deal with liquid bridge configurations ͑either axisymmetric or nonaxisymmetric͒ that are held between circular supports. Therefore, except for the above quoted papers, the effects of noncircular supports have never been considered, and no efforts have been devoted to the study of the behavior of liquid bridges held between noncircular supports ͑although some early work concerning capillary jets emerging from noncircular nozzles has been published 14 ͒.…”