The aluminum-rich part of the system BaO-Al2O3-MgO - II: Crystal structure of the beta-alumina-related compound, Ba2Mg6Al28O50

摘要

The crystals of a new phase, Ba2Mg6Al28O50, recently confirmed to exist in the system BaO-Al2O3-MgO, were grown by the floating zone method, and its crystal structure was determined by using single-crystal X-ray diffraction, The space group was P (6) over bar m2 with lattice parameters a = 5.638 Angstrom and c = 31.983 Angstrom. Structure refinement revealed stacking of conduction layers of the beta-alumina-type (BaO) separated by an extended spinel block ((Al,Mg)(17)O-24). This is the same structure with Na beta'''-alumina whose ideal formula is Na2O . 4MgO . 15Al(2)O(3) (Na2Mg4 Al30O50). (C) 1998 Academic Press. [References: 30]