Mössbauer and x‐ray study of the self‐induced magnetostatic distortion of TbxY1−xFe2 Laves phases

A comparison has been made between x‐ray diffraction data and Mo/sbauer absorption data for a series of ferrimagnetic compounds TbxY1−xFe2. Previous work has shown that the volume and the rhombohedral angle of the disorted ’’cubic’’ unit cell both vary with the Tb concentration x, but that the disortion disappears for x ≲0.25. Having noted that this is close to the concentration where the rare‐earth and the iron sublattice magnetizations are equal and opposite, we made a detailed study of the 57Fe Mossbauer spectra for these compounds in the vicinity of x=0.25. Our results confirm the previous finding that the magnetic hyperfine field veries continuously with the Tb concentration. Also, they reveal that the Fe sites are not all equivalent chemically and crystallographically, and that this is true wheather or not the rhombohedral distortion is present. This suggests that in addition to the rhombohedral disoration there may be an independent distotion or shifting of the iron tetrahedra within the unit cube.