Opening a new series of calcium boridecarbides with heterographene nets by Ca_(1-x)(B,C)_6and Ca_(1-x)(B,C)_8 - Two members of the (CaB_2)C_n compound series

摘要

Ca_(1-x)B_2C_4 (x ～ 0.08) and Ca _(1-x)B_2C_6 (x ～ 0.04) are two compounds containing heterographene-B,C nets which were prepared by solid state synthesis and structurally characterized by X-ray powder diffraction data. Both compounds crystallize in the space group P6/ mmm (No. 191). The lattice constants are a = 4.55971(5) ? and c = 4.4020(1) ? for CaB_2C_4 and a = 2.58390(5) ?, c = 4.43597(8) ? for CaB_2C _6. The calcium atoms are intercalated between, the heterographene (B,C) nets. The calcium atom distribution in Ca_(1-x)B_2C _6 is disordered, leading to diffuse scattering. A model for this disorder was developed that matches well the observed diffuse scattering observed in the electron diffraction pattern. For Ca_(1-x)B _2C_6 and its decomposition products magnetic and electric properties are being reported.