[Zr0.72Y0.28]Al4C4: A new member of the homologous series (MC)l(T4C3)m (M=Zr, Y and Hf, T=Al, Si and Ge)

A new layered carbide, [Zr_0.72(3)Y_0.28(3)]Al₄C₄, has been synthesized and characterized by X-ray powder diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX). The atom ratios [Zr:Y] were determined by EDX, and the initial structure model was derived by the direct methods, and further refined by Rietveld method. The crystal is trigonal (space group , Z=1) with lattice dimensions of a=0.333990(5) nm, c=1.09942(1) nm and V=0.106209(2) nm³. This compound shows an intergrowth structure with [Zr_0.72Y_0.28C₂] thin slabs separated by Al₄C₃-type [Al₄C₄] layers. It is a new member with l=1 and m=1 of the homologous series, the general formula of which is (MC)_l(T₄C₃)_m (l=1, 2 and 3, m=1 and 2, M=Zr, Y and Hf, T=Al, Si and Ge).