Applying the chemical bonding theory of single crystal growth to a Gd3Ga5O12 Czochralski growth system: both thermodynamic and kinetic controls of the mesoscale process during single crystal growth

Abstract

The chemical bonding theory of single crystal growth was applied to a Gd₃Ga₅O₁₂ (GGG) Czochralski growth system. On the basis of anisotropic chemical bonding characteristics, the mesoscale process controlled by both thermodynamics and kinetics has been studied in GGG single crystal growth. Starting from the unit-scale in the growth system, the mesoscale structures undergo evolution from GdO₈, GaO₆, and GaO₄ to Gd₃Ga₅O₁₂ clusters and to a GGG single crystal via chemical bonding between Gd, Ga, and O. On the basis of the chemical bonding theory of single crystals, the GGG single crystal thermodynamically prefers to exhibit a hexagonal configuration along the [111] pulling direction. Kinetically, isotropic mass transfer in the Czochralski growth process leads to formation of a GGG single crystal with a circular configuration, as viewed down along the [111] direction. In such a case, the GGG single crystal maintains the lowest energy. In order to satisfy both thermodynamic and kinetic controls, the thermodynamically preferred {−110} microfacets are exposed on the microscale and the single crystal adopts a circular shape on the macroscale. The present work deepens our understanding of the mesoscale process in the GGG Czochralski growth system.