Tb_0.67PdAl₃ and Gd_1.33Pt₃Al₈ with layers of rare-earth-metal atoms and Al-atom triangles

Chem. Met. Alloys 1 (2008) 303-316

https://doi.org/10.30970/cma1.0078

Yuriy LUTSYSHYN, Yaroslav TOKAYCHUK, Volodymyr DAVYDOV, Roman GLADYSHEVSKII

The crystal structures of the ternary compounds Tb_0.67PdAl₃ (hP14-4.67, P6₃/mmc, a = 4.394(4), c = 9.372(6) Å) and Gd_1.33Pt₃Al₈ (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, Sc_0.67Fe₂Si₅, 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 Tb_0.67PdAl₃ structure.

Keywords

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