| 摘要 |
PROBLEM TO BE SOLVED: To synthesize a thin-chip form particle which is flat in shape and capable of maintaining a stable dispersing state in an aqueous solvent while maintaining a uniform shape and dispersing property of a single particle which are characteristics of an alumina particle obtainable by hydrothermal synthesis. SOLUTION: The thin-chip formα-alumina particle has an average particle diameter of 0.5 to 25μm, a flat shape with aspecto ratio (average particle diameter/thickness of particle) of 50 to 2,000 (without including 50). A phosphoric compound is present in an amount of 0.2-5.0 wt.% as P2 P5 with respect to the alumina particle. An alumina hydrate or an alumina gel is a starting material having an average diameter of <=2μm and a maximum diameter of <=5μm, and an aqueous slurry is hydrothermally synthesized by adding phosphoric ions of 1.0×10<-3> -1.0×10<-1> mol to 1 mol of the alumina hydrate or the alumina gel.
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