The Titanium—Iron—Antimony Ternary System and the Crystal and Electronic Structure of the Interstitial Compound Ti5FeSb2.

Abstract Phase equilibria were established in the Ti–Fe–Sb ternary system below the TiSb2–FeSb section at 1070 K; the Sb–TiSb2–FeSb region was studied at 870 K. Investigation of the phase relations was based on X-ray diffraction experiments on arc-melted bulk alloys, which were annealed up to 350 h. Four ternary compounds were observed: TiFe1−xSb (0.64≤x≤0.70; defect TiNiSi-type), Ti1.18Fe0.57Sb (partially and statistically filled Ni2In-type), Ti1+xFeSb (−0.20≤x≤0.27; transformation from defect AlLiSi-type to the defect MnCu2Al-type), and new Ti5FexSb3−x (0.45≤x≤1.00; W5Si3-type). An extended solid solution up to about 10 at.% antimony was observed for the Laves phase Ti(Fe1−xSbx)2−y. Ti3Sb seems to dissolve up to 1.4 at.% of Fe replacing titanium in the structure. At 800 °C there is no solid solubility of Ti in the iron antimonides and of Fe in the titanium antimonides with an Sb content higher than 25 at.%. Electronic band structure calculations indicate that Ti5FeSb2 is metallic and completely spin polarized with Fe as the carrier of the magnetic moments.