Synthesis and crystal structure of a new ternary compound Ca4Al3Mg

The ternary compound Ca4Al3Mg was successfully synthesized by induction melting of appropriate amounts of pure metals followed by annealing at 773 K for 14 days. The crystal structure was determined by X-ray powder diffraction. Ca4Al3Mg crystallizes in space group Pbcm (No. 57); cell parameters: a = 6.1792(1) Å, b = 24.2113(5) Å, c = 5.8864(1) Å; Z = 4. This structure can be built up of the alternating layers of two types of chains. The first type of chains consists of Al3 triangles sharing one corner and the second one contains AlMg2 triangles sharing one of the Mg corners. Both of them run along the crystallographic c-axis, forming atomic layers normal to the b-axis.