Isothermal section of the Er–Cu–Ga ternary system at 973 K

Highlights: ► The isothermal section at 973 K of the Er–Cu–Ga ternary phase diagram has been established for the first time. ► Eight extensions of binary compounds in the ternary domain have been identified, as well as six ternary intermediate solid solutions characterized by an important Cu/Ga mutual substitution. ► Magnetic properties of Er3(Cu,Ga)11 are reported for the first time and confirms the paramagnetic Curie–Weiss behavior of all the six intermediate intermetallics. - Abstract: Phase relations in the Er–Cu–Ga ternary system have been established at 973 K by means of powder X-ray diffraction complemented by energy dispersive spectroscopy coupled to scanning electron microscopy. The isothermal section of the phase diagram comprises eight extensions of binaries into the ternary system, ErCu1−xGax (x ≤ 0.5), ErCu2−xGax (x ≤ 1.1), ErCu5−xGax (x ≤ 0.5), Er5CuxGa3−x (x ≤ 0.60), Er3CuxGa2−x (x ≤ 0.24), ErCuxGa1−x (x ≤ 0.10), ErCuxGa2−x (x ≤ 0.30) and ErCuxGa3−x (x ≤ 0.35), as well as six ternary intermediate phases, ErCuxGa2−x (0.4 ≤ x ≤ 0.7), Er14Cu51−xGax (5.5 ≤ x ≤ 11.0), ErCu5−xGax (0.8 ≤ x ≤ 2.3), Er2Cu17−xGax (4.9 ≤ x ≤ 8.0), ErCu12−xGax (5.7 ≤ x ≤ 6.7) and Er3CuxGa11−x (1.5 ≤ x ≤ 4.4), all deriving from binary structure-types.