Bromides of Rare Earth Metal Boride Carbides —A System of Building Blocks

摘要

Only a tew metal-rich rare earth metal halkies MX_n with n <= 2 are known nameh M_2X_3 and Lal. Other compounds described as binary phases and accessible in low yields, however, finally turned out to be "stabilized" by interstitial atoms. Due to the electropositive nature of the rare earth metals these interstitial atoms have anionic character. Addition of H. C. N. O in experiments to reduce rare earth trihalides led to numerous new ternary compounds, whose structures could be systematized in terms of a condensation of characteristic building units: M_4O tetrahedra, M_6N, double tetrahedra. M_4H tetrahedra. and M_6H_2 octahedra as well as M_6C and M_6C_2 octahedra were repeatedly found. These units can be combined as was demonstrated recently with compounds containing the interstitial atoms C/H, C/O, and C/N simultaneously. Here we report new phases with B C which particularly well illustrate this building block principle.