Identification and characterisation of three novel compounds in the sodium–aluminium–oxygen system
Abstract
Reactions of sodium oxide with α-Al2O3 have produced three novel sodium-rich aluminates, Na7Al3O8(triclinic, space group P), Na17Al5O16(monoclinic, space group Cm), and Na5AlO4(orthorhombic, space group Pbca). X-Ray crystal structure determinations have shown Na7Al3O8 to consist of infinite double chains composed of Al6O16 rings linked by oxygen bridges, Na17Al5O16 to consist of discrete Al5O16 chains of corner-sharing AlO4 tetrahedra with almost linear angles about the bridging oxygens, and Na5AlO4 to be composed of isolated AlO4 tetrahedra.