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 VSr + VO or VSr + 2VO. 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.