Synthesis and Crystal Structure of a New Layered Carbide ZrAl ₈ C ₇

Abstract

A new ternary layered carbide, ZrAl 8 C 7 , has been synthesized and characterized by X‐ray powder diffraction. The crystal structure was determined using direct methods, and further refined by the Rietveld method. The crystal is trigonal (space group R 3 m, Z =3) with lattice dimensions a =0.332842(2) nm, c =5.78221(2) nm, and V =0.554754(4) nm 3 . The sample prepared was composed mainly of ZrAl 8 C 7 with a small amount of ZrAl 4 C 4 . These two types of carbides have been found to form a homologous series with the general formula (ZrC) m Al 8 C 6 , where m =1 and 2. They show comparable intergrowth structures consisting of [Zr m C m +1 ] layers separated by [Al 8 C 7 ] layers.