Growing of bulk sapphire single crystals using laser material deposition

A device to grow oxide single crystals via powder based laser additive manufacturing has been built and successfully tested. Single crystals of sapphire as demonstrator materials have been grown to prove the ability of this technique. A sapphire seed disk with a diameter of 25.4 mm is heated in a high temperature furnace up to 1550 °C. Through a hole of the furnace-lid, the seed disk is irradiated by CO2 laser radiation. Simultaneously, Al2O3 powder is fed into the furnace via ceramic tubes. The molten material solidifies on the seed material with exactly the same crystallographic orientation, thus retaining the single crystal structure. A crack free single crystal of a few millimeters in height is produced.