Structural, optical, and photocatalytic properties of Bi1–xRExFeO3 (RE=La, Ce, Pr, Nd, Sm; x=0, 0.05, 0.1) thin films

Abstract

Bismuth ferrite perovskite materials have recently attracted great attention because of their unique properties. In this study, Bi_1–xRE_xFeO₃ (RE = La, Ce, Pr, Nd, Sm; x = 0, 0.05, 0.1) thin films were deposited on glass substrates via low-temperature sol–gel assisted spin coating procedure. It is found that in the presence of light rare-earth ions as the substitutions, the structural, morphological, and optical properties of the thin films are changed in the prepared thin films. We find that the thin films have rhombohedral structures, and from field emission scanning electron microscopy (FESEM) images, it is observed that the substitution of light rare-earth ions for Bi³⁺ affects the surface morphology and grain size of the BiFeO₃ (BFO) thin film. Moreover, the optical properties of prepared films were investigated via UV–visible spectroscopy. For all samples, the bandgap energy values are between 1.22 and 1.65 eV. Also, the refractive index and extinction coefficient of samples are about 1.14–1.41 and 0.1–0.6, respectively. Photocatalytic properties of the samples were investigated by measuring the degradation of methylene blue (MB) dye under irradiation of sunlight. We find that the light rare-earth substituted BFO thin films have better photocatalytic activity compared to pure BiFeO₃ thin film, the reason can be described as the band gap varied between 1.20 and 1.65 eV for different rare earth ions which directly influences the photocatalytic properties of the investigated samples. It is observed that the prepared thin films can remove between 37.18% and 69.14% of dye after 180 min of irradiation. This study confirms that prepared thin films are a suitable candidate for photocatalytic applications.