Solid State Phase Equilibria in the Fe—Ga—Sb Ternary System at 600 °C.

Abstract

Abstract Solid state phase equilibria in the ternary Fe–Ga–Sb diagram were determined at 600 °C using experimental techniques such as X-ray diffraction, electron probe microanalysis and scanning electron microscopy. Very limited solid solutions were measured in the binary constituent Fe–Ga and Fe–Sb compounds except for the e-phase (Fe ≈2.55 Sb 2 ) which extends from 42 to 48 at.% Sb. In the Fe-rich part of the diagram, a ternary phase Fe t Ga 2− x Sb x (2.15≤ t ≤2.80) was evidenced which corresponds in fact to a solid solution into which Ga and Sb substitute one another on the same hexagonal sublattice. This phase, which can be truly considered as a pseudo-binary one since its origin results from the e-phase, shows an extended homogeneity range with a Ga-rich limit corresponding to the formula Fe t Ga 0.8 Sb 1.2 . Moreover, it crystallizes in hexagonal symmetry with a disordered structure derivative from the NiAs-type ( B 8 1 ). This pseudo-binary phase is in thermodynamic equilibrium with all the binaries of the system except FeGa 3 . The main result of the ternary Fe–Ga–Sb diagram remains the existence of a diphasic region between the Fe t Ga 2− x Sb x phase (1.2≤ x ≤1.6; 2.15≤ t ≤2.80) and the semiconductor GaSb. Nevertheless, at 600 °C, this pseudo-binary phase does not extend up to the Fe 3 GaSb composition which is stoichiometric in Ga and Sb. Finally, a comparative study has been made with the three other ternary systems Fe–Ga–As, Ni–Ga–As and Ni–Ga–Sb previously reported, and the consequences for the solid state interdiffusions in Metal/III–V semiconductor heterostructures are discussed.