[en] The effect of diamagnetic ions on the magnetic ordering in ferrites has been studied by neutron diffraction measurements on Mg and Zn substituted Li/sub 0.5/Cr/sub 0.5/Fe₂O₄ and Li/sub 0.25/Zn/sub 0.5/Fe/sub 2.25/O₄ samples prepared by the usual ceramic method. The cation distributions and the magnetic structure were obtained by refinement methods. The results show that the replacement of (Li/sub 0.5/⁺Cr/sub 0.5/³⁺) by Mg or Zn does not affect the A-site magnetic moment, but the B-site moment is significantly reduced. There is a possible canting of moments on the B-site. Some of the B-site magnetic ions are rendered paramagnetic by the addition of diamagnetic ions