Observation of enhanced multiferroic, magnetoelectric and photocatalytic properties in Sm-Co codoped BiFeO3 nanoparticles

Abstract

Single phase multiferroics BiFeO3 (BFO), Bi0.99Sm0.01FeO3 (Sm1) and Bi0.99 Sm0.01Fe0.99Co0.01 O3 (Sm1Co1) were successively synthesized by tartaric acid assisted sol-gel method. The X-ray diffraction patterns analyzed through Rietveld refinement method confirmed substitution driven structural distortion, which was further supported by William- Hall plot. The morphological analysis of BFO and Sm1Co1 could be effectively controlled to form nanoparticles, due to the smaller ionic radii of the dopants cations. The co-doping of Sm and Co in BFO lattice significantly enhanced the magnetic properties, with the saturation magnetization being 8.4 emu/g, which is about 20 times larger than that of pure BFO (0.40 emu/g). The decrease of Neel transition temperature and irreversible behavior of FC/ZFC curves also support improved magnetic properties. With the codoping of Sm-Co, the band gap was decreased, while interestingly, the leakage current density was significantly reduced to about 10−7 A cm−2. A reduction of oxygen vacancies was confirmed by XPS analysis in the case of Sm1Co1 sample. The codoping leads to improved ferroelectric properties and significant enhancement of magnetoelectric coupling coefficient (9mV/cmOe). The photocalalytic activity of Sm1Co1 enhanced significantly and about 92% degradation of methylene blue dye was achieved using this catalyst under visible light irradiation.