Li0.5Fe2.5O4 has been studied by means of Mossbauer spectroscopy and x
-ray diffraction. The crystal is found to have a cubic spinel structur
e with the lattice constant a(0) = 8.344 +/- 0.005 Angstrom. The iron
ions are in ferric states. The temperature dependences of the magnetic
hyperfine fields at the Fe-57 nuclei at the tetrahedral (A) and octah
edral (B) sites are analysed using the Neel theory of ferrimagnetism.
The intersublattice superexchange interaction is found to be antiferro
magnetic with a strength of J(A-B) = -10 8k(B) while the intrasublatti
ce superexchange interactions are ferromagnetic with strengths of J(A-
A) = 17.6k(B) and J(B-B) = 17.8k(B). The Debye temperatures of the tet
rahedral and octahedral sites are determined to be 398 +/- 5 K and 362
+/- 5 K, respectively.