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Schlagwörter:
Borides; Chlorine compounds; Crystal atomic structure; Energy gap; High pressure effects in solids; Microcrystals; Semiconducting silicon compounds; Silica; Silicides; Silicon oxides; Atomic arrangement; Crystals structures; Diffraction tomography; High pressure high temperature; High temperature condition; Pearson symbol; Quantum chemical calculations; Quantum-chemical calculation; Space Groups; Synthesised; Sodium compounds
Zusammenfassung:
The compound Na2B6Si2 was synthesized under high-pressure, high-temperature conditions at pressures ranging from 6 to 9.5 GPa and temperatures from 1070 to 1270 K before quenching to room temperature followed by slow decompression. The crystal structure was determined from microcrystals using precession-assisted electron diffraction tomography, validated by dynamical refinement and full-profile refinements using optimized coordinates from quantum chemical calculations (space group R3̅m, Pearson symbol hR30, a = 5.0735(1) Å and c = 16.0004(7) Å). The atomic arrangement consists of a unique framework formed by electron-precise octahedral closo (B6)2- clusters connected via ethane-like (Si2)0 dumbbells. The Na+ cations occupy cavities in the hierarchical variation of a Heusler-type framework. The balance (Na+)2([B6]2-)(Si0)2 reveals an electron precise Zintl-Wade phase, which is in line with electronic band structure calculations predicting semiconducting behavior. © 2024 The Authors. Published by American Chemical Society.
