Great ferroelectric properties and narrow bandgaps of BiFeO3 thin films by (Mg, Mn) modifying

• Published in: Applied surface science 2022-06, Vol.586, p.152751, Article 152751
• Main Authors: Liang, Xia-Li, Dai, Jian-Qing, Zhang, Guo-dong
• Format: Article
• Language: English
• Subjects: (Mn, Mg) co-doping; BiFeO3 thin film; Ferroelectric properties; Narrower bandgap; Sol-gel; Spin coating
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.152751

(a) Ferroelectric hysteresis loops and (b) plots of (ahv)2 versus hv curves of the BiFe1-2xMnxMgxO3 (x = 0–5 mol%) thin films. [Display omitted] •High-quality modified BiFe1-2xMgxMnxO3 (BFMMO-x, where ×  = 0–5 mol%) films were successfully prepared on FTO/glass as substrates via the sol–gel method.•High residual polarization value (Pr = 214.8 μC/cm2) is obtained and confirmed to be spontaneous polarization (ΔP = 410.5 μC/cm2).•A significant widening in the visible absorption range and a decrease in the bandgap were observed from 2.19 to 1.82 eV. High-quality modified BiFe1-2xMgxMnxO3 (BFMMO-x, x  = 0–5 mol%) films were successfully prepared via the sol–gel method. The influence of (Mg, Mn) doping amounts on the crystal structure, oxygen vacancy content, leakage mechanism and optical, ferroelectric and electrochemical properties of the BFMMO films was investigated. All samples exhibited a pure perovskite phase and successful doping of the (Mg, Mn) at the Fe site was achieved. As the stoichiometric ratio increased, the structural distortion of the octahedra increased, resulting in the formation of homogeneous microstructures. XPS measurements illustrated that the replacement of Fe3+ with Mn and Mg ions effectively suppressed the generation of oxygen defects and increased the concentration of Fe3+ ions of the perovskite lattice. A high spontaneous polarization Pr (214.8 μC/cm2), ΔP (410.5 μC/cm2) and low leakage (1.5 × 10−8A/cm2) as well as a good dielectric constant (388.0) and loss (0.017) were simultaneously attained in the BFMMO-4thinfilm. A significant widening in the visible absorption range and a decrease in the bandgap were observed from 2.19 to 1.82 eV. By simultaneously introducing Mg and Mn into the BFO, enabling both a higher polarization and narrower bandgap, a novel method for improving the performance of BFO-based devices was achieved.