A Mössbauer study of Fe3-xAlxO4 and Fe3-xGaxO4 has been undertaken. Measurements at low temperatures in magnetic fields enabled us to better separate the Fe(A) and Fe(B) subspectra and to determine the cation distribution on tetrahedral and octahedral sites. Whereas Al up to x=1.4 shows a strong preference for B sites, giving rise to a normalization of the spinel structure with Fe2+ located mainly in tetrahedral sites, Ga distributes over both A and B places without tendency towards normalization at least below x¿1.2.
Rosenberg, M., Deppe, P., Janssen, H. U., Brabers, V. A. M., Li, F. S., & Dey, S. (1985). A Mössbauer study of Al and Ga substituted magnetite. Journal of Applied Physics, 57(8), 3740-3742. https://doi.org/10.1063/1.334954