کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1617802 | 1005695 | 2011 | 9 صفحه PDF | دانلود رایگان |
We report the synthesis of the new compounds R15Si9C with R = Sm, Gd–Er, Y and R15Ge9C with R = Ce, Pr and Nd. These compounds crystallize in the hexagonal La15Ge9Fe structure type (hP50, P63mc, Z = 2) which is an ordered superstructure of La5Ge3 (Mn5Si3-type, hP16, P63/mcm, Z = 2). The superstructure is absent in a single-phase R5Ge3C0.33 alloy with R = Sm and Gd. The addition of interstitial carbon modifies the magnetic properties significantly as regards the magnetic transition temperature and the nature of the magnetic ordering. Carbon doping induces mostly a ferromagnetic or ferrimagnetic configuration. The preponderance of ferromagnetic interactions in the superstructure compounds, with respect to the parent phases, can tentatively be attributed to a change in the sign of the RKKY interactions. The dense Kondo lattice state of Ce in ferrimagnetic Ce5Ge3 is preserved in Ce15Ge9C. Large coercive fields (∼4–5 kOe) at low temperatures are observed in most compounds, which exceed ∼50 kOe in the two Sm based compound.
► We report the synthesis of the new compounds R15Si9C, with R = Sm, Gd–Er, Y and R15Ge9C with R = Ce, Pr and Nd.
► The compounds crystallize in the hexagonal La15Ge9Fe structure type (hP50, P63mc, Z = 2), ordered superstructure of La5Ge3 (Mn5Si3-type, hP16, P63/mcm, Z = 2).
► The superstructure is absent in the R5Ge3C0.33 phases with R = Sm and Gd.
► The addition of interstitial carbon modifies the magnetic properties significantly, both increasing the magnetic ordering temperature and mostly inducing ferromagnetic or ferrimagnetic configurations.
Journal: Journal of Alloys and Compounds - Volume 509, Issue 23, 9 June 2011, Pages 6509–6517