The invention relates to a particle blend comprising mainly or consisting of an oxide phase of the pseudo-brookite type comprising at least titanium and aluminum, said blend being obtained from at least two particle size fractions, namely a coarse particle size fraction, the median diameter d50 of which is greater than 12 microns, and a fine particle size fraction, the median diameter d50 of which is between 0.5 and 3 microns, the mass ratio of said coarse fraction to said fine fraction being between 1.5 and 20, limits inclusive, and the ratio of the median diameter of the coarse fraction to that of the fine fraction being greater than 12.