Impact of annealing atmosphere on the multiferroic and dielectric properties of BiFeO3/Bi3.25La0.75Ti3O12 thin films

Multiferroic BiFeO₃/Bi_3.25La_0.75Ti₃O₁₂ films annealed in different atmospheres (N₂ or O₂) were prepared on Pt/Ti/SiO₂/Si substrates via a metal organic decomposition method. Based on our experimental results, it is considered that, in the films annealed in N₂, fewer Fe²⁺ ions while more oxygen vacancies are involved. As a result, at room temperature, predominated by the reduced Fe²⁺ fraction, lower leakage current and dielectric loss, better ferroelectric property while reduced magnetization are observed. However, the oxygen vacancies might be thermally activated at elevated temperature; thus, more strongly temperature-dependent leakage current and a higher dielectric relaxation peak are observed for the films annealed in N₂.