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RESEARCH PRODUCT

The titanium–iron–antimony ternary system and the crystal and electronic structure of the interstitial compound Ti5FeSb2

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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.