Phase equilibria in systems Ce– M–Sb ( M=Si, Ge, Sn) and superstructure Ce 12Ge 9−xSb 23+x ( x=3.8±0.1)

Abstract

Phase relations in the ternary systems Ce– M–Sb ( M=Si, Ge, Sn) in composition regions CeSb 2–Sb– M were studied by optical and electron microscopy, X-ray diffraction, and electron probe microanalysis on arc-melted alloys and specimens annealed in the temperature region from 850 to 200 °C. The results, in combination with an assessment of all literature data available, were used to construct solidus surfaces and a series of isothermal sections. No ternary compounds were found to form in the Ce–Si–Sb system whilst Ce 12Ge 9− x Sb 23+ x (3.3< x<4.2) and CeSn x Sb 2 (0.1< x<0.8) participate in phase equilibria in the composition region investigated. Crystallographic parameters for the ternary compound Ce 12Ge 9−xSb 23+x ( x=3.8±0.1) were determined from X–ray single crystal and powder diffraction. For the binary system Ge–Sb a eutectic was defined L⇔(Ge)+(Sb) at 591.6 °C and 22.5 at%. Ge EPMA revealed a maximal solubility of 6.3 at% Ge in (Sb) at the eutectic temperature.