Growth, structure and defects of (La,Sr)(Al,Ta)O₃ crystals for preparing BiFeO₃ thin films

A new (La,Sr)(Al,Ta)O₃ (LSAT) crystal is focused on in this paper to be used as an ideal substrate for preparing perfect BiFeO₃ thin films. The crystal structures are designed with a low lattice mismatch between LSAT and BiFeO₃. LSAT crystals were grown by the Czochralski method. In order to get colourless crystals with high transmittance, density functional theory is used to simulate the crystals with different defects. From the results, it is found that the colour centre originates from the defect of V_Sr + V_O or V_Sr + 2V_O. Thus, it is necessary for the crystals to be annealed in O₂ and then in N₂. High-quality BiFeO₃/LSAT thin films will have promising application prospects.