Fibers and square sapphire shaped single crystals grown from the melt and optical characterization

Abstract The micro-pulling down technique has been used to grow fibers ( ϕ = 1 mm) and square (2 × 2 mm 2 ) sapphire shaped single crystals with controlled sizes. The hot zone construction and fiber pulling conditions have been optimized. As a result, growth of transparent and homogeneous sapphire shaped crystals has been performed. The crystals have been grown under 1 bar of argon atmosphere with pulling rate varied in the range of 0.5–3 mm/min. 100% of the melt has been continually transformed into crystalline sapphire with empty crucible at the end of the growth operation. The as grown crystals show high chemical homogeneities and good optical properties.