A DFT+U look into experimentally synthesized monoclinic scheelite BiVO4
Jannatul Fardush Tanha, Syed Farid Uddin Farhad, Ummay Honey, Nazmul Islam Tanvir, Tarique Hasan, Sadiq Shahriyar Nishat, Alamgir Kabir, Shahran Ahmed, Mahmuda Hakim, M. N. I. Khan, Mohammad Moniruzzaman, Imtiaz Ahmed
Abstract
We present a combined experimental and Hubbard interaction corrected density functional theory (DFT+U) based study of monoclinic scheelite (ms) bismuth vanadate BiVO4 (BVO). The ms-BVO samples were synthesized using the standard solid state reaction technique. The ms phase of the synthesized BVO samples has been confirmed from Rietveld analysis of the powder x-ray diffraction pattern and room temperature Raman spectroscopy. Both experimentally obtained crystal parameters and Raman peak positions were benchmarked against the DFT+U simulations. The variations in morphology and chemical concentrations due to different sintering temperatures and milling times were analyzed using field emission scanning electron microscopy and energy dispersive x-ray spectroscopy. The measured energy bandgap in the range of 2.38–2.58 eV from UV-Vis-NIR diffuse reflection spectroscopy was explained within the context of grain size variations in combination with bismuth and oxygen vacancies from DFT+U simulations.