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

In the Sm-Fe-Zr system, a hexagonal 2:17-type phase (2:17H, Th2Ni17-type) is observed in the isothermal section at 1000 °C. Previous investigations have shown, that in the binary Sm–Fe system only the rhombohedral Sm2Fe17-phase (2:17R, Th2Zn17-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, TbCu7-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.