Syntheses and crystal structures of Si-bearing layered carbides ZrAl8C7 and ZrAl4C4

Two types of new quaternary carbide solid solutions, (ZrC)[Al1-xSix]8C6 with x = 0.06 and (ZrC)[Al1-ySiy]4C3 with y = 0.04, have been synthesized and characterized using a laboratory X-ray powder diffraction (Cu K α1), transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX). The average atom ratios [Al:Si] of both carbides were determined by EDX, and the crystal structures were refined using the Rietveld method. These carbides have been found to form a homologous series with the general formula (ZrC)m[Al1-zSiz]8C6 (0 ≤ z ≤ 0.07), where m = 1 and 2. The crystal structures can be regarded as intergrowth structures, consisting of the NaCl-type [ZrmCm+1] slabs separated by the Al4C3-type [(Al1-zSiz)8C7] layers.