Stabilization of the Perovskite Phase in the Y-Bi-O System By Using a BaBiO3 Buffer Layer

A topological insulating phase has theoretically been predicted for the thermodynamically unstable perovskite phase of YBiO3. Here, it is shown that the crystal structure of the Y–Bi–O system can be controlled by using a BaBiO3 buffer layer. The BaBiO3 film overcomes the large lattice mismatch of 12% with the SrTiO3 substrate by forming a rocksalt structure in between the two perovskite structures. Depositing an YBiO3 film directly on a SrTiO3 substrate gives a fluorite structure. However, when the Y–Bi–O system is deposited on top of the buffer layer with the correct crystal phase and comparable lattice constant, a single oriented perovskite structure with the expected lattice constants is observed.