Both the dc and ac magnetic susceptibilities as well as magnetization measurements were used to study
the influence of the dilution of the magnetic chromium subarray by nonmagnetic antimony and aluminium
ions on the magnetization processes for four spinel families under investigation. Substitution of the chromium
ions by the nonmagnetic Sb and Al ions in the compounds under study leads to the very hard magnetization
in the case of the compounds with Sb and very easy magnetization in the compounds with Al. This
effect is connected with the electronic configurations of the Sb and Al ions as well as with ionic radii of these cations
