Abstract: Ionomer particles with an inner area and an outer area are provided. The outer area has an oxidic matrix with cations selected by observing the following conditions. Only two different types of cations must be present that belong to one of the following groups (a) to (d), and these two types of cations must be selected from two different ones of the groups (a) to (d): (a) ions of the elements of the second main group and bivalent ions of the transition elements and the lanthanides; (b) ions of the elements of the third main group with the exception of boron and trivalent ions of the transition elements and the lanthanides; (c) ions of the elements of the fourth main group with exception of carbon and tetravalent ions of the transition elements and the lanthanides (d) ions of the elements of the fifth main group, selected from ions of antimony and bismuth and pentavalent ions of the transition elements. Particles of the composition ZrO2—Y2O3, ZrO2—Al2O3, BaToO3, Al6Si2O13 are not contained.