SYSTEM Tb–Ni–C AT 800 °C. CRYSTAL AND ELECTRONIC STRUCTURE OF TbNiC2 SINGLE CRYSTAL

Abstract

Phase equilibria at 800 °C in the concentration part up to 33.3 at. % Tb of the Tb–Ni–C system were determined. Three ternary compounds Tb 11 Ni 60 C 6 , Tb 2 Ni 5 C 3 and TbNiC 2 have been found to occur at thermodynamically equilibrium conditions. Crystal structure of TbNiC 2 was refined by means of a single crystal X-ray diffraction method: structure type CeNiC 2 , space group Amm2, a = 3.6010(7) Å, b = 4.5110(9) Å, c = 6.046(1) Å, R 1 = 2.2 %, wR 2 = 5.2 %. Real-space chemical bonding analysis indicates the TbNiC 2 compound represents a unique series of ternary carbide structures stabilized by complex interaction of different types of chemical bonding.