| abstract |
Alunite compound particles of the general formula: Ma[Al1-xM’x]3(SO42-)y(OH)z•mH2O (I) (wherein M is at least one cation selected from the group consisting of Na+, K+, NH4+ and H3O+; M’ is at least one cation selected from the group consisting of Cu2+, Zn2+, Ni2+, Sn4+, Zr4+ and Ti4+; and a, m, x, y and z satisfy the relationships: 0.8≤a≤1.35, 0≤m≤5, 0≤x≤0.4, 1.7≤y≤2.5 and 4≤z≤7), wherein when D25 and D75 respectively refer to the particle diameters at 25% value and 75% value of cumulative particle size distribution curve measured according to laser diffractometry, D75/D25 satisfies specified value. These particles have small average particle diameters and are shaped like spheres, disks or hexagonal plates, and are further characterized by having extremely narrow particle diameter distribution. |