Enhanced Structural, Optical, and Multiferroic Properties of Rod-Like Bismuth Iron Oxide Nanoceramics by Dopant Lanthanum

Herein, the influence of lanthanum concentration on the structural, thermal, optical, ferroelectric, and magnetic properties of Bi_1-xLa_xFeO₃ (BLFO, x = 0, 0.05, 0.1, 0.15, 0.2, and 0.25) nanorods prepared by hydrothermal method was investigated. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were performed to study the structural properties of BLFO nanoparticles for different lanthanum concentration. The Rietveld refinement and analysis of crystal structure revealed a single-phase perovskite structure with space group R3c. Transmission electron microscope (TEM) image of bismuth iron oxide nanorods exhibits average diameter of ~ 40 nm and length of ~ 2 μm. The ferroelectric Curie temperature of 833 °C (829 °C) was determined for BiFeO₃ (Bi_0.8La_0.2FeO₃) by differential thermal analysis (DTA). Diffuse reflectance UV-Vis spectra indicated that the optical band gap is decreased by increasing the lanthanum concentration. The ferroelectric properties of BiFeO₃ nanoparticles also improved by adding lanthanum into the structure of bismuth iron oxide. Moreover, J-E curves showed that lanthanum doping can significantly decrease the leakage current of bismuth ferrite nanorods. Finally, vibrating sample magnetometer (VSM) measurements indicated that the weak ferromagnetic behavior is observed for as-prepared BLFO nanorods with x ≤ 0.15. However, for the 20 mol% lanthanum doping, a magnetic transition from weak ferromagnetic to antiferromagnetic occurred.