Experimental and DFT investigation of structural and optical properties of lanthanum substituted bismuth ferrites

In this work, Bi1-xLaxFeO3 [0 ≤ x ≤ 0.08, step 0.02] was successfully prepared by the co-precipitation method. The as-synthesized samples were investigated by using XRD, SEM, FT-IR, and UV–vis spectroscopy. To get a deep insight into its properties, Density Functional Theory (DFT) was also performed. Calculations have been executed using Wien2k code by employing LDA + U. XRD patterns revealed hexagonal perovskite structure with R3c space group having average crystallite size from 19 to 39 nm. Rietveld refinement was also performed to identify the different phases presented. SEM results showed a spherical-like morphology. UV–vis spectroscopy results showed that the energy band gap decreased by increasing lanthanum substitution. DFT calculations revealed optical absorption onsets of 2 eV, 2.1 eV, 1.98 eV and 1.86 eV for Bi1-xLaxFeO3 samples for pure and substituted bismuth ferrite were in good agreement with experimental results. Because of these qualities, these materials are excellent candidates for various applications including electromagnetic attenuation, switching and microwave devices.