Slab Rotation by Transition‐Metal Relocation in the Layered Zintl Phase Li2ZnSi

Layered crystal structure of Li₂ZnSi with honeycomb-like [ZnSi]²⁻ networks and interlayer Li atoms forming a Lonsdaleite-type substructure. Despite local stacking faults corresponding to 60° rotations of individual layers, the average structure retains P6₃/mmc symmetry. The Zintl phase forms congruently from the melt and features metallic conductivity.

The layered Zintl phase Li₂ZnSi is a structural analog of intercalated graphite with hexagonal layers of Zn and Si atoms separated by Li atoms (space group P6₃/mmc, a = 4.2458(2) Å, c = 8.224(1) Å). Single-crystal X-ray diffraction reveals Zn relocation into the center of the Zn₃Si₃ rings in 4% of the hexagonal layers. The Zn relocation is coupled with Li migration. The resulting 2D defects can be modeled either as 60° slab rotations or, alternatively, as layer translations by k  = 1/3 [1,−1,0]. Li₂ZnSi shows metal-type electrical resistivity (ρ = 1.18 μΩ m at 300 K) and exhibits significantly enhanced diamagnetism, suggesting orbital contributions akin to those in graphite. This study demonstrates transition-metal mobility in a layered Zintl phase, generating localized 2D defects that leave the local coordination of each atom unchanged. This mechanism is relevant for understanding defect tolerance in structurally related electrode materials.

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