Variable excitation wavelength photoluminescence response and optical absorption in BiFeO₃ nanostructures

Abstract

In this paper we present uniformly distributed ~100 nm BiFeO₃ nanoparticles synthesized by conventional chemical co-precipitation method in order to scrutinize structural, optical, photoluminescence and dielectric properties. The Rietveld refinement of the X-ray diffraction pattern revealed that the sample is single phase in nature and crystallizes in rhombohedral structure with R3c space group. The average crystallite size and particle strain were estimated by using Debye–Scherer’s and Hall–Williamson method. The particle size of the BiFeO₃ nanoparticles is ~100 nm with uniform size distribution predicted by the field-emission scanning electron micrographs. The effective band-gap of the nanostructures calculated as 2.74 eV along with additional defect levels determined by plotting Tauc relation. The Photoluminescence response of BiFeO₃ nanoparticles is extensively observed across the UV–Visible spectrum by illuminating the sample with different excitation wavelengths from ~280 to ~360 nm. Photoluminescence also specifies the characteristic band-gap of crystalline BiFeO₃ ~2.96 eV, along with some prominent energy levels near the conduction and valence band edge that may appear due to nano-structuring. The chemical bonds between the constituent elements of the specimen are traced with FTIR spectroscopy. The dielectric study identifies low frequency dispersive nature of the specimen.