Fabrication, structural characteristics, and influence of Bi3+ doping concentration on UV-vis spectra of Bi3+:SnO2 nanocomposite materials

Abstract

The authors report the characteristics and optical properties of Bi³⁺-doped SnO₂ quantum dots prepared by sol-gel and hydrothermal methods. The structure and morphology of the materials as a function of doping concentration were studied and analysed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The structure of the material was assigned to the tetragonal crystal structures of the SnO₂ rutile phase, reported in JCPDS Card No. 41-1445. With the increase of Bi³⁺ doping, the crystallinity of Bi-doped SnO₂ worsened. The average sizes of the SnO₂ nanocrystals were within 3-8 nm. The effect of Bi³⁺ ion concentration on the absorbance properties of the materials was investigated by UV-Vis absorption spectra. The absorbance decreased with increasing the concentration of Bi³⁺ dopant in the SnO₂ lattice. The bandgap width decreased with Bi³⁺ dopant concentration. All Bi³⁺-doped SnO₂ samples presented an enlargement of the light absorption range due to a bandgap width decrease.