Constitution, structural chemistry and magnetism in the ternary system Ce–Ag–Si

Abstract

Phase relations were established for the Ce–Ag–Si system at 850°C by means of X-ray diffraction, light optical microscopy and quantitative electron probe microanalysis. Phase equilibria are characterised by the existence of extended solid solutions starting from the binaries: Ce(Ag x Si 1− x ) 2− y (ThSi 2-type), Ce(Ag 1− x Si x ) 1− y (unknown structure type) and Ce(Ag 1− x Si x ) 2− y (unknown structure type). Three ternary phases were found to exist, CeAg 2Si 2 (ThCr 2Si 2-type), Ce(Ag x Si 1− x ) 2− y (AlB 2-type) and the new ternary compound CeAgSi 2 with unknown structure type. Magnetic behaviour was studied from magnetic susceptibility and magnetisation measurements down to 1.7 K and employing magnetic fields up to 5 T. Soft ferromagnetism is observed for CeAg x Si 2− x (AlB 2-type) below 5 K. Alloys Ce(Ag x Si 1− x ) 2− y with 0.08< x Ag<0.30 (ThSi 2-type) encounter ferromagnetic order below 7 K. For x Ag=0.31 the ferromagnetic interaction changes to antiferromagnetism with T N=5.7 K. For CeAgSi 2 ferrimagnetic or canted antiferromagnetic order is indicated below 7 K.