The ternary system Sc-Co-In at 870 K. The isothermal section and the crystal structures of the compounds

The isothermal section of the Sc-Co-In system at T = 870 K has been constructed using X-ray powder diffraction and SEM/EDX data. At the studied temperature, nine ternary compounds are formed: Sc${}_{50}$Co${}_{12.5}$In${}_{3.5}$ (Ag${}_{7+x}$Mg${}_{24-x}$-type structure, space group Fm$\overline{3}$, a = 17.7411 Å), Sc${}_{14}$Co${}_{3.10}$In${}_{2.59}$ (Lu${}_{14}$Co${}_3$In${}_3$ type, P4${}_2$/nmc, a = 8.8913, c = 21.387 Å), Sc${}_6$Co${}_{2.18}$In${}_{0.82}$ (Ho${}_6$Co${}_2$Ga type, Immm, a = 8.867, b = 8.780, c = 9.321 Å), Sc${}_2$CoIn (Pt${}_2$ZnCd type, P4/mmm, a = 3.2887, c = 7.1642 Å), Sc${}_{11}$Co${}_4$In${}_9$ (Nd${}_{11}$Pd${}_4$In${}_9$ type, Cmmm, a = 13.836, b = 20.758, c = 3.351 Å), Sc${}_5$Co${}_2$In${}_4$ (Lu${}_5$Ni${}_2$In${}_4$ type, Pbam, a = 17.3400, b = 7.5940, c = 3.3128 Å), Sc${}_3$Co${}_{1.64}$In${}_4$ (Lu${}_3$Co${}_{2-x}$In${}_4$ type, P$\overline{6}$, a = 7.6702, c = 3.3595 Å), Sc${}_{10}$Co${}_9$In${}_{20}$ (Ho${}_{10}$Ni${}_9$In${}_{20}$ type, P4/nmm, a = 12.8331, c = 9.0226 Å), Sc${}_{0.5}$In${}_{0.5}$Co${}_2$ (ternary non-centrosymmetric derivative of the Laves phase MgNi${}_2$, P6${}_3$mc, a = 4.8910, c = 16.0166 Å, with a homogeneity range from 12.3 to 16.7 at% of indium). The cubic phase ScCo${}_4$In (MgCu${}_4$Sn type, F$\overline{4}$3m, a = 6.9230(8) Å) is evidently present in the cast samples and disappears after the annealing procedure. A Sc/In substitution was observed for the solid solution Sc${}_{1-x}$In${}_x$Co${}_2$ (x = 0-0.26) with the structure of the cubic Laves phase (MgCu${}_2$ type) and also for the hexagonal Sc${}_{0.5}$In${}_{0.5}$Co${}_2$-type phase.