has been studied by means of Mössbauer spectroscopy and x-ray diffraction. The crystal is found to have a cubic spinel structure with the lattice constant . The iron ions are in ferric states. The temperature dependences of the magnetic hyperfine fields at the nuclei at the tetrahedral (A) and octahedral (B) sites are analysed using the Néel theory of ferrimagnetism. The inter-sublattice superexchange interaction is found to be antiferromagnetic with a strength of while the intra-sublattice superexchange interactions are ferromagnetic with strengths of and . The Debye temperatures of the tetrahedral and octahedral sites are determined to be and , respectively.
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Oak et al. (1998) studied this question.
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