Syntheses, crystal structures and Si solubilities of new layered carbides Zr2Al4C5 and Zr3Al4C6

Two types of new ternary carbides, Zr2Al4C5 and Zr3Al4C6, have been synthesized and characterized by X-ray powder diffraction. The crystal structures were refined from laboratory X-ray powder diffraction data (CuKα1) using the Rietveld method. These carbides form a homologous series with the general formula (ZrC)mAl4C3 (m=2 and 3). The crystal structures can be regarded as intergrowth structures where the Al4C3-type [Al4C4] layers are the same, while the NaCl-type [ZrmCm+1] layers increase in thickness with increasing m value. The new carbides are most probably the end members of continuous solid-solutions (ZrC)m[Al4−xSix]C3 with 0⩽x⩽0.44.