Crystal structure of hexagonal SrAl 2O 4 at 1073 K

Abstract

The crystal structure of SrAl 2O 4 at 1073 K was determined from conventional X-ray powder diffraction data using direct methods, and it was further refined by the Rietveld method. The structure was hexagonal (space group P6 3, Z = 6 ) with a=0.89260(3) nm, c=0.84985(2) nm and V=0.58639(3) nm 3. Final reliability indices were R wp=7.87%, R p=5.87% and R B =4.19%. The [AlO 4] tetrahedra are linked to form trigonally distorted rings and they are joined in layers. These layers are stacked with a two-layer repeat and connected by the tetrahedral apices. All of the Sr atoms occupy the centers of the rings when viewed along the c-axis. The structure is described as a stuffed derivative of tridymite.