Tb0.67PdAl3 and Gd1.33Pt3Al8 with layers of rare-earth-metal atoms and Al-atom triangles

 

Chem. Met. Alloys 1 (2008) 303-316

 

Yuriy LUTSYSHYN, Yaroslav TOKAYCHUK, Volodymyr DAVYDOV, Roman GLADYSHEVSKII

 

The crystal structures of the ternary compounds Tb0.67PdAl3 (hP14-4.67, P63/mmc, a = 4.394(4), c = 9.372(6) Å) and Gd1.33Pt3Al8 (hR51-14.00, R-3m, a = 4.3090(14), c = 38.54(2) Å) were refined from X-ray single-crystal diffraction data. They contain monoatomic layers stacked along [001] with ordered or disordered distribution of rare-earth-metal atoms and Al-atom triangles. Together with the structures of Y2Co3Ga9, Sc0.67Fe2Si5, Er4Pt9Al24, and ErNi3Al9, they form a family of intergrowth structures built up of three kinds of monoatomic layer. Analyzing the relative positions of the monoatomic layers, some basic stacking rules, which may help to predict new structures, are formulated.

 

The unit cell and coordination polyhedra for atoms in the Tb0.67PdAl3 structure.

 

Keywords

Aluminide / Rare-earth metal / Noble metal / Single-crystal X-ray diffraction / Intergrowth layered structure