Phase relationships in the La–Fe–Sb system at 773 K

The isothermal section of the phase diagram of the La–Fe–Sb ternary system at 773 K has been investigated mainly by X-ray powder diffraction with the aid of metallographic analysis and electron probe microanalysis techniques. Two ternary compounds Fe4LaSb12 and LaFe2Sb2 have been confirmed and LaFe2Sb2 is a new ternary compound which was found in this system at 773 K. This isothermal section consists of 12 single-phase regions, 23 two-phase regions and 12 three-phase regions.According to the results of experiment, the homogeneity range of ɛ(FeSb) phase extended from about 44 to 46 at.% Sb, the maximum solid solubility of La in ɛ phase is about less than 1 at.% La at 773 K. The solubilities for the other single-phase regions were not observed. The structure type for LaFe2Sb2 is Ga2S3-type (sp. gr. Cc (No. 9), a = 0.45518 nm, b = 0.77737 nm, c = 0.84207 nm, β = 128.3946°). FeLaSb2 and La3Sb2 have not been observed at this isothermal section.