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The temperature dependence of the magnetic hyperfine fields on 57 Fe nuclei at the tetrahedral (A) and octahedral (B) interstitial sites in (Zn, Cd, Cu) 0.5 Ni 0.5 Fe 2 O 4 oxides have been investigated in Mössbauer measurements at sample temperatures ranging from 79 K to 850 K. The samples were prepared by solid-state reaction, and their phase determined from XRD measurements, which also provided information on their X-ray densities, grain sizes and lattice constants. The magnetic transition temperatures between ordered and paramagnetic states were obtained from zero-velocity measurements. The Cu 0.5 Ni 0.5 Fe 2 O 4 sample is found to be antiferromagnetic with Néel temperature of 823 K, and its super-exchange interactions, J AB , J AA and J BB were determined to be j24.14 k B , j13.10 k B and +11.68 k B , respectively. The (Zn, Cd) 0.5 Ni 0.5 Fe 2 O 4 are ferrimagnetic with Curie points of 543 and 548 K, respectively, and corresponding average exchange integrals J o = 186 k B and 188 k B .

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