| Abstract: | Three samples consistent with 1 : 12, 2 : 17 and 1 : 7 stoichiometry, ball-milled and subsequently annealed at temperature Ta between 600 and 1200°C were studied by Rietveld analysis, coupled to Curie temperature Tc measurements and Mössbauer spectroscopy. For all samples, at 600°CTa<900°C, the detected out-of-equilibrium phase is the hexagonal P6/mmm structure derived from TbCu7 with the composition SmFe9. At Ta900°C the ordered
phase of Th2Zn17-type is observed. With increasing Ta the unit cell parameter small variation of the parent SmFe9 induces a decrease of Tc and Hhf. For Ta=600°C SmFe9 is defined by a=0.4919 nm, c=0.4162 nm, Tc=207°C and Hhf=232 kOe. The resulting ordered Sm2Fe17 is characterized by
nm, c=3×0.4147 nm, Tc=144°C and Hhf=219 kOe. For Ta=750°C the SmFe9 Tc is 171°C associated to Hhf=222 kOe. |
