No abstract

Aurivillius phases are compounds with the general formula (Am−1BmO3m+1)2− (Bi2O2)2+ that consist of (m − 1) perovskite‐like units interrupted by bismuth oxide layers. Compounds with A = {Ba2+; Sr2+}, B = {Nb5+}, and m = 2 are studied by EXAFS spectroscopy and X‐ray diffraction. The lattice parameters a and c of the tetragonal phase, studied by X‐ray diffraction, increase with increasing Ba content. The short‐range order environment of Ba, Sr, and Bi ions are analyzed for several Ba:Sr ratios using EXAFS spectroscopy. It is found that the Ba and Sr ions substitute each other in a solid solution. Their different ionic radii cause a tilting and distortion of the surrounding NbO6 octahedra. The first BiO interatomic distances are not influenced by the composition. Thus, the (Bi2O2)2+ layers possess a very high stability and determine the structure of the unit cell.