* Crystallography on demand : mixture of triclinic and monoclinic phases or 100% alpha phase available on request. * Shape : perfectly spherical and full dense. * Mean diameter : 25 µm or 80 µm * Density : apparent 2,3, taped 2,4 * Specific surface area : 0,08 m² / g * Chemical purity : 99,998% Al 2O3 :