We report that the ternary MgB2-xCx compounds adopt an isostructural AlB2-type hexagonal structure in a relatively small range of nominal carbon concentration, x<0.1. The lattice parameter α decreases almost linearly with increasing carbon content x, while the c parameter remains unchanged, indicating that carbon is exclusively substituted in the boron honeycomb layer without affecting the interlayer interactions. The superconducting transition temperature Tc decreases quasilinearly as a function of the carbon concentration, with a slope steeper than that for the isoelectronic Mg1-xAlxB2.
|Number of pages||3|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2001 Oct 1|