Ni-x(Cu0.5Fe0.5)(1-x)Cr2S4 has been studied by Mossbauer spectroscopy
and X-ray diffraction. The crystal is found to have a cubic spinel str
ucture and the lattice constant decreases with increasing Ni concentra
tion. The iron ions are in ferric states and occupy the tetrahedral si
tes. When the nickel concentration at the tetrahedral sites increases
from 10 to 30%, magnetic hyperfie held and Neel temperature are found
to decrease by 2 and 9%, respectively. As the interatomic distance dec
reases by 0.4%, Debye temperature increases rapidly by 37%.