Micro-tube Sapphire Crystal Grown by the Edge-defined-film Fed Method

Sapphire rod with micro-tube (inner diameter: 470 m) and sapphire plate with micro-tube (inner diameter: 160 m) were grown by the edge-defined-film fed method (EFG). Profile curves of the small liquid menisci were investigated on the base of numerical solution of the Young-Laplace equation. By inserting Mo wires, new type of die was designed to form and sustain size of micro-tube in the volume of the crystal. Two problems were solved at the same time: 1) obtaining high quality sapphire crystal; 2) forming and sustaining necessary micro-tube sizes in the volume of the crystal. The crystal were transparent, colorless, no cracking and good XRC value of 3.8 arcmin, demonstrating the high quality of the as-grown crystal.