作者: Natascha Vojteer , Melanie Schroeder , Caroline Röhr , Harald Hillebrecht
关键词: Electronic structure 、 Network covalent bonding 、 Chemistry 、 Band gap 、 Orthorhombic crystal system 、 Ternary compound 、 Knoop hardness test 、 Raman spectroscopy 、 Crystallography 、 Crystal structure
摘要: We present the synthesis, crystal structure, hardness, IR/Raman and UV/Vis spectra, FP-LAPW calculations of electronic structure Li(2)B(12)Si(2), first ternary compound in system Li/B/Si. Yellow, transparent single crystals were synthesized from elements tin as solvent at 1500 degrees C h-BN crucibles arc-welded Ta ampoules. Li(2)B(12)Si(2) crystallizes orthorhombic space group Cmce (no. 64) with a=6.1060(6), b=10.9794(14), c=8.4050(8) A, Z=4. The is characterized by a covalent network B(12) icosahedra connected Si atoms Li located interstitial spaces. closely related to that MgB(12)Si(2) fulfils electron-counting rules Wade Longuet-Higgins. Measurements Vickers (H(V)=20.3 GPa) Knoop microhardness (H(K)=20.4 revealed hard material. band gap was determined experimentally calculated theoretical means. spectra 2.27 eV, which value 2.1 eV agrees well. IR Raman show expected oscillations icosahedral networks. Theoretical investigations bonding this carried out method. results confirm applicability simple enable some structural specialties be explained more detail.