Crystal structure and reference X-ray pattern of Ba_4Ti_10Al_2O_27

摘要

the crystal structure of Ba_4Ti_10Al_2O_27 has been refined in a joint Rietveld refinement using neutron and X-ray powder data. The compound crystallizes in the monmoclinic space group C2/m, with a =19.7057(3), b=11.3575(2), c=9.8318(2) A, β=109.218(1)°, and V=2077.81(5)A~3. It is isostructural to Ba_4Ti_10Fe_2O_27 and Ba_4Ti_11ZnO_27, and consists of a complex network of corner-and edge-sharing Ti/Al octahedra. The structure can best be described based on close-packed O/Ba-O layers in an 8-layer (8L) chhcchhc sequence.