Synchrotron studies of novel Tb2Ni5C3: Crystal and electronic structure

New ternary phase Tb₂Ni₅C₃ was gained in the three-phases sample of nominal composition after 90 d annealing at 800 °C. Crystal structure of Tb₂Ni₅C₃ was determined using synchrotron powder diffraction: structure type La₂Ni₅C₃, space group P4/mbm, a = 8.2372(1) Å, c = 3.83402(6) Å, R_B = 5.0%; R_p = 1.8%. Crystallographic analysis and electronic structure calculations confirm the La₂Ni₅C₃-isotypes including Tb₂Ni₅C₃ refer to carbometalates. Metallic bonding is predominant in the R₂Ni₅C₃ compounds. Novel La₂Ni₅C₃-isotypic compounds were synthesized with rare earths Sm and Gd. Their unit cell parameters have been determined from X-ray powder diffraction data.