The Aurivillius phases of complex bismuth oxides have attracted considerable attention because of their lattice polarization (ferroelectricity) and photocatalytic activity. We report a first-principles exploration of Bi2WO6 and the crystal engineering through replacing W6+ by pentavalent (Nb5+ and Ta5+) and tetravalent (Ti4+ and Sn4+) ions, with charge neutrality maintained by the formation of a mixed anion oxyhalide sublattice. We find that Bi2SnO4F2 is thermodynamically unstable, in contrast to Bi2TaO5F, Bi2NbO5F, and Bi2TiO4F2. The electric dipoles introduced by chemical substitutions in the parent compound are found to suppress the spontaneous polarization from 61.55 μC/cm2 to below 15.50 μC/cm2. Analysis of the trends in electronic structure, surface structure, and ionization potentials is reported. This family of materials can be further extended with control of layer thicknesses and choice of compensating halide species.
Bibliographical noteFunding Information:
This research has been partially supported by Keio University Research Grant for Young Researcher’s Program, Yoshida Scholarship Foundation, Japan Student Services Organization, and Centre for Doctoral Training on Theory and Simulation of Materials at Imperial College London. Part of computation in this work has been done using the facilities of the Supercomputer Center, Institute for Solid State Physics, University of Tokyo. Some of the calculations were also carried out in the UK national Archer HPC facility, accessed through membership of the UK Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202).
© 2019 American Chemical Society.