A new representative of the structure type Sc_0.6Fe₂Si_4.9 in the Tm‒Pd‒Al‒Ga system

Chem. Met. Alloys 16 (2023) 52-58

Denys OLEKSIUK, Nataliya MUTS, Yaroslav TOKAYCHUK, Roman GLADYSHEVSKII

https://doi.org/10.30970/cma16.0437

The crystal structure of the new quaternary phase Tm_0.67Pd₂(Al_0.79(7)Ga_0.21(7))₅ was refined from X-ray powder diffraction data (structure type Sc_0.6Fe₂Si_4.9, Pearson symbol hP20, space group P6₃/mmc, a = 4.28311(9), c = 16.3748(4) Å). The crystal structure belongs to a homologous series of structures with the general formula (R_0.67)_mT_nM_{2n+m, and} consists of monoatomic layers of the compositions Tm_0.67M (m = 1) and PdM₂ (n = 2), where M is a statistical mixture of aluminum and gallium atoms. The Tm_0.67(Al,Ga) layers are built from Tm atoms (Wyckoff position 2c) and triangles, formed by Al and Ga atoms (position 6h), in the ratio 2:1.

Arrangement of atomic layers in the structures of Tm_1.33Pd₃(Al_0.91Ga_0.09)₈ and Tm_0.67Pd₂(Al_0.79Ga_0.21)₅.

Keywords

Tm‒Pd‒Al‒Ga system, X-ray diffraction, crystal structure, Sc_0.6Fe₂Si_4.9 structure type