Search

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) A, c = 3.83402(6) A, RB = 5.0%; Rp = 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.

A new metastable solid phase CeCr1−x (x ≈ 0.89) was detected by x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDX) methods in 0.5-g as-cast samples of the Ce–Cr system. CeCr1−x crystallizes with the cubic NaCl structure type (space group $$Fm\overline{3}m$$ ) with 4b site partially (~10 %) occupied by chromium. The lattice parameter of CeCr1−x varies from 0.5441(1) to 0.5585(3) nm, indicating a narrow homogeneity range. CeCr1−x decomposes into γ-Ce and Cr after annealing at 600 °C for 1 month.