Numerical and Experimental Investigation of Crystal Growth Rate Dependence on Facet Undercooling for Dielectric Crystal Growth from the Melt

Abstract

Combined experimental and numerical tools are developed and used to define more exactly the growth kinetic relations for (211) crystallographic orientation of Bi4Ge3O12 (BGO) crystal growth—namely, the dependence of crystal growth rate V on supercooling, ΔT of the melt/crystal interface. A new apparatus for in situ measurements of the time dependence of the supercooling, ΔT(t), was used, and a new, two-dimensional numerical model was applied to analyze the effect of temperature boundary conditions and faceting phenomena on the character of the observed V(ΔT) dependence. The measurements of the ΔT(t) dependence show that there is a large enough undercooling and a novel effect of the appearance of the local maximum on ΔT(t) dependence at the finish of crystallization. Results on V(ΔT) dependence show that, for the variant of the crystal growth technique used (melt cooling during axial heating process method [AHP]), the type of the V(ΔT) dependence does not depend on boundary conditions. The new investigations illustrate the superlinear behavior for V(ΔT) dependence for (211) BGO crystallographic orientation and show that previous data on sublinear behavior of V(ΔT) dependence for this crystallographic orientation of BGO have not been justified.