Growth method for single crystals of magnesium aluminate spinel by edge-defined film-fed growth technique

A growth method for single crystals of magnesium aluminate spinel by an edge-defined film-fed growth technique, comprising:

• 1) loading:
• putting seed crystals and crystal growth raw materials into a crystal growth furnace;
• 2) vacuuming and gas-filling:
• vacuuming the crystal growth furnace and then filling with inert gas;
• 3) heating and melting:
• raising the temperature of the crystal growth furnace to 2130-2200° C., so that the crystal growth raw materials are melted;
• 4) seeding:
• making the seed crystals contact a top end of a seam of a mold, and then pulling the seed crystals so that the crystal growth raw materials condense and grow on the seed crystals;
• an upper heat shield and a lower heat shield are arranged above the mold, and a cross section of a slit between the upper heat shield and the lower heat shield is a curved surface;
• 5) necking:
• pulling the seed crystals to shrink the crystals crystallized on the surfaces of the seed crystals;
• 6) shouldering:
• thickening and widening the crystals in an upward pulling process;
• 7) equal-width growth:
• making the crystals grow with the width of the mold in the upward pulling process;
• 8) annealing:
• after the end of crystal growth, starting annealing to cool down.