METHOD OF CRYSTALLIZING METALLIC OXIDE

PURPOSE:To grow seed crystal and to from large-sized single crystal of metallic oxide by skull melt method, by irradiating the metallic oxide with microwave, and heating and melting it from the interior by self-heat generation by dielectric loss. CONSTITUTION:Four quarters of water-cooling type vertically divided cylinder 1 made of stainless steel are integrated with the steel bottom plate 2, and fastened by the bands 3 at the upper and lower parts, to form the cylinder. The seed crystal 11 of single crystal of a metallic oxide such as alumina, etc. is placed on the central part of the bottom plate 2, and high-purity alpha-alumina powder is fed from the feeder 8 to the bottom plate. When the bottom plate 2 is covered with the powder, it is irradiated with microwave from the waveguide 4, the alpha-alumina is melted, the metallic oxide is cooled from the bottom toward the top with rise of the melt level 9, and inverted conical crystallization having the single crystal 11 as a seed is advanced towards the top. The bands 3 are removed, skull whose outer face is covered with the metallic oxide powder and the polycrystalline crust 10 is obtained and the outer face crust is removed to give the cylindrical alumina single crystal 12 having an inverted conical shape at the bottom and almost the same size as the cylinder 1 is obtained.