Magnetoelectric Coupling Effects in Tb-Doped BiFeO3 Nanoparticles

Abstract

The magnetic, electric, and optical properties in Tb-doped BiFeO3 nanoparticles as functions of size and doping concentrations were investigated using a microscopic model, taking into account both linear and quadratic magnetoelectric (ME) coupling. We observed improved multiferroic properties and band-gap tuning. The magnetization and polarization increased with the decreased nanoparticle size and increased Tb-doping substitution x. The Neel temperature remained nearly unchanged whereas the Curie temperature was reduced with the increased x. There was doping-induced ME coupling. The dielectric constant is discussed as a function of the size, doping, and the magnetic field. The band gap decreased with the decreased size or increased Tb dopants due to competing effects of the compressive strain, oxygen defects on the surface, and Coulomb interactions. Increasing the Tb dopants and decreasing the nanoparticle size improved the ME effect.

Effect of heavy rare‐earth substitution on physical properties of BiFeO3 thin films and their photocatalytic application

“…The energy difference between the bottom of the conduction band Fe-3d and the top of the valence band O-2p corresponds to the optical band-gap energy of BFO material. 40 As can be seen in the inset of Figure 6, the substitutions of RE ions for Bi 3+ in BFO show a significant steady decline in the band-gap energy of the BFO. For the heavy rare-earth substituted BFO thin films, the band-gap energies are between 1.18 and 1.65 eV.…”

“…According to Table 3, in comparison with previous works, the present study shows lower E g values. 39,40 The shape, size distribution, and structure type can play an important role in the bandgap of nanoparticles. The low band-gap energies (E g ) of the heavy rare-earth substituted BFO thin films show that these compounds can be suitable for use as visible light-responsive photocatalysts for the degradation of organic pollutants.…”