Structural effects of Zr substitution in the 1:7- and 2:17-type structure

Abstract In the Sm-Fe-Zr system, a hexagonal 2:17-type phase (2:17H, Th 2 Ni 17 -type) is observed in the isothermal section at 1000 °C. Previous investigations have shown, that in the binary Sm–Fe system only the rhombohedral Sm 2 Fe 17 -phase (2:17R, Th 2 Zn 17 -type) is stable. Addition of Zr leads to the formation of the hexagonal 2:17H modification, where Zr substitutes for Sm and Fe. By annealing of rapidly solidified material both phases were obtained from the metastable 1:7-phase (1:7, TbCu 7 -type). In this work, the crystal structure of (Sm, Zr) 1 (Fe, Zr) 7–8.5 compounds has been analysed and the transformation processes between 1:7 and 2:17 as well as between 2:17R and 2:17H are discussed. A modified structure of the Zr-rich 2:17R- and 2:17H-phase is supposed.