Lan(n+1)+ xNin(n+5)+ ySi(n+1)(n+2)- z: A Symmetric Mirror Homologous Series in the La-Ni-Si System

Davide Grilli; Volodymyr Smetana; Sheikh J Ahmed; Vitalii Shtender; Marcella Pani; Pietro Manfrinetti; Anja-Verena Mudring

doi:10.1021/acs.inorgchem.3c01194

La_{n(n+1)+ x}Ni_{n(n+5)+ y}Si_{(n+1)(n+2)- z}: A Symmetric Mirror Homologous Series in the La-Ni-Si System

Inorg Chem. 2023 Jul 10;62(27):10736-10742. doi: 10.1021/acs.inorgchem.3c01194. Epub 2023 Jun 26.

Authors

Davide Grilli^{1

2

3}, Volodymyr Smetana^{1

4}, Sheikh J Ahmed^{1

4}, Vitalii Shtender⁵, Marcella Pani^{2

3}, Pietro Manfrinetti^{2

3}, Anja-Verena Mudring^{1

4}

Affiliations

¹ Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius väg 16 C, Stockholm 10691, Sweden.
² DCCI, Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, Genova I-16146, Italy.
³ Institute SPIN-CNR, Corso Perrone 24, Genova I-16152, Italy.
⁴ Department of Biological and Chemical Engineering and iNANO, Aarhus C 8000, Denmark.
⁵ Department of Chemistry─Ångström Laboratory, Uppsala University, Box 538, Uppsala 75121, Sweden.

Abstract

A series of four homologous silicides have been discovered during systematic explorations in the central part of the La-Ni-Si system at 1000 °C. All compounds La_12.5Ni_28.0Si_18.3 (n = 3; a = 28.8686(8), c = 4.0737(2) Å, Z = 3), La_22.1Ni_39.0Si_27.8 (n = 4; a = 20.9340(6), c = 4.1245(2) Å, Z = 1), La_32.9Ni_49.8Si_39.3 (n = 5; a = 24.946(1), c = 4.1471(5) Å, Z = 1), and La_44.8Ni_66.1Si_53.4 (n = 6; a = 28.995(5), c = 4.158(1) Å, Z = 1) crystallize in the hexagonal space group P6₃/m and can be generalized according to La_n(n+1)+xNi_n(n+5)+ySi_(n+1)(n+2)-z with n = 3-6. Their crystal structures are based on AlB₂-type building blocks, fused La-centered Ni₆Si₆ hexagonal prisms, yielding larger oligomeric equilateral domains with the edge size equal to n. The domains extend along the c axis and show checkered ordering of the cationic and anionic parts, while all their atoms are located on mirror planes. La_n(n+1)+xNi_n(n+5)+ySi_(n+1)(n+2)-z can be considered as a mirror series to the La-rich La_(n+1)(n+2)Ni_n(n-1)+2Si_n(n+1), where an exchange of the formal cationic and anionic sites, i.e., La and Si, occurs. The La-Ni-Si system is the first system where two such analogous series have been observed.