Intermetallic and metal-rich phases in the system Li-Ba-In-N

Three new intermetallic phases, BaLi_2.1In_1.9, BaLi_1.12In_0.98, and BaLi_1.06In_1.16 and two subnitrides Li₃₅In₄₅Ba₃₉N₉ and LiIn₂Ba₃N_0.83 have been synthesized and their crystal structures have been determined. According to single crystal X-ray diffraction data BaLi_2.1In_1.9 and BaLi_1.12In_0.98 crystallize with hexagonal symmetry (BaLi_2.1In_1.9: P6₃/mmc, a=10.410(2), c=8.364(2) Å, Z=6, V=785.0(2) Å³) and BaLi_1.12In_0.98: P6/mmm, a=17.469(1), c=10.6409(7) Å, Z=30, V=2813.5(8) Å³), while BaLi_1.06In_1.16 has a rhombohedral structure (R-3c, a=18.894(3), c=85.289(17) Å, Z=276, V=26368(8) Å³). BaLi_2.1In_1.9 is isostructural with the known phase BaLi₄. The phase BaLi_1.12In_0.98 is structurally related to Na₈K₂₃Cd₁₂In₄₈, while BaLi_1.06In_1.16 is isostructural with Li_33.3Ba_13.1Ca₃. A sample containing structurally similar BaLi_1.12In_0.98 and BaLi_1.02In_1.16 was also investigated by transmission electron microscopy. Li₃₅In₄₅Ba₃₉N₉ and LiIn₂Ba₃N_0.83 crystallize with tetragonal (I-42m, a=15.299(2), c=30.682(6) Å, Z=2, V=7182(2) Å³) and cubic (Fd-3m, a=14.913(2) Å, Z=8, V=3316.7(7) Å³) symmetry, respectively. While the first-mentioned subnitride belongs to the Li₈₀Ba₃₉N₉ structure type, the second extends the structural family of Ba₆In_4.78N_2.72. The structural features of the new compounds are discussed in comparison to the known phases and the results of total energy calculations.