Photocatalytic activity and magnetic enhancements by addition of lanthanum into the BiFeO₃ structure and the effect of synthesis method

In this paper, the photocatalytic activity, as well as the magnetic enhancement of multiferroics BiFeO₃ (BFO) and Bi_0.8La_0.2FeO₃ (BLFO) nanocrystals with two different morphologies, synthesized by two different sol–gel and hydrothermal (HT) methods, have been studied. All the obtained samples were characterized using X-ray diffractometer, Fourier transform infrared spectroscopy, transmission electron microscopy, UV–Vis spectroscopy and vibrating sample magnetometer. Differential thermal analysis measurements were probed ferroelectric- paraelectric first-order phase transition (T_C) for all samples. Addition of lanthanum decreases the electric phase transition. For photocatalyst application of bismuth ferrite, adsorption potential of nanoparticles for methylene blue (MB) organic dye was evaluated. The doping of La in the BFO structure enhanced the photocatalytic activity and about 71% degradation of MB dye was obtained under visible irradiation. The magnetic properties of BLFO nanoparticles improve compared to the undoped BiFeO₃ nanoparticles. The non-saturation at high applied magnetic field for as-prepared samples by HT is related to the size and shape of products. This work not only presents an effect of 20 mol% lanthanum substitution into the bismuth ferrite structure on the physical properties of BFO, but also compares the synthesis method and its influence on the photocatalytic activity and multiferroics properties of all nanopowders.