| abstract |
The present invention provides polycrystalline cerium oxide powder in the form of aggregates of primary particles having a specific surface area of 70 to 150 m 2 / g, an average primary particle diameter of 5 to 20 nm, and an average projection aggregate diameter of 20 to 100 nm. It is about. The cerium oxide powder is prepared by reacting aerosol in a flame obtained from an oxygen-containing combustible gas and primary air, and then separating the obtained solid from a gaseous material, whereinn n n Introducing at least the same amount of secondary air as the primary air into the reaction chamber,n n n For lambdas, in fact, 1.1 ≦ lambda ≦ 1.5 (here, lambda is calculated from the quotient of the sum of the fraction of oxygen in the gases divided by the sum of the cerium compound and the oxygen-containing combustible gas being oxidized),n n n The rate of release of the liquid droplets from the atomizer device to the reaction chamber is greater than 500 mm / sn n n The speed of the reaction mixture in the reaction chamber is greater than 2 m / s.n n n The present invention also relates to a dispersion containing the cerium oxide powder. |