The LiAlSi ternary system has been investigated and four ternary phases characterized using both powder and single crystal X-ray diffraction data. LiAlSi and Li7Al3Si4 crystallize in the F-43m, cubic system, Li18Al2Si6 in tetragonal I41/amd and Li15Al3Si6 in hexagonal P63/m space group. The structure of LiAlSi (a = 5.94 Å), previously reported from powder data, has been confirmed. The new compound Li7Al3Si4 has been identified and, due to a higher lithium content, its cell parameter is slightly larger (a = 6.115 Å). The tetragonal cell (a = 6.179(1) Å, c = 12.199(4) Å) of Li18Al2Si6 may be considered as a (1 × 1 × 2) supercell of the cubic one. Structural variations are strongly correlated to compositional fluctuations and atomic substitutions, in every case the SIAl network displays some covalent character. In the Li15Al3Si6 hexagonal cell, bonding is more covalent leading to a heterographite-like SIAl network.
Print ISSN: 0044-2968
Volume: 218, 11/2003
Pages: 740