Structural stability of layered n -LaFeO 3 -Bi 4 Ti 3 0 12 , BiFeO 3 -Bi 4 Ti 3 0 12 , and SrTiO 3 -Bi 4 Ti 3 0 12 thin films

A series of layered n -ABO 3 -doped Aurivillius structures Bi 4 Ti 3 0 12 (BTO) thin films are synthesized on (001) SrTiO 3 (STO) substrates by pulsed laser deposition, where n represents the number of ABO 3 perovskite. X-ray diffraction substantiates that these films have expected layered Aurivillius structures. Furthermore, the microstructure of these samples is “systematically” characterized by transmission electron microscopy. It is found that the structure of n-STO-doped BTO becomes unstable when n is equal to 3, as revealed by the occurrence of intergrowth. Similar phenomenon is observed in n-LaFeO 3 -doped BTO; the layered Aurivillius structure is totally collapsed in the case of n as high as 2.5. In contrast, 3-BiFeO 3 -doped BTO still keeps perfect Aurivillius structure. The above-observed structural stabilities of these materials are explained by the theoretical formation enthalpy calculated by the density functional theory. This work provides the necessary information to explore the multifunctionality based on Aurivillius n -ABO 3 -BTO oxides.