Influence of Ca doping on X‐ray photoelectron core‐level spectra of magnetoelectric bulk BiFeO <sub>3</sub>
B. Ramachandran, Ambesh Dixit, M. S. Ramachandra Rao, R. Naik
Abstract
The X‐ray photoelectron spectrum (XPS) core‐level spectra of pristine and doped bulk BiFeO 3 , namely Bi 0.9 Ba x Ca y FeO 3 with x + y = 0 and 0.1 were recorded on the Ar + ‐ion sputtered sample surface at room temperature. Afterward, the obtained XPS spectra of Bi 4 f , Fe 2 p , O 1 s , Ba 3 d and Ca 2 p levels were inspected using the symmetric Gaussian‐Lorentzian product function, to study the influence of the spin‐orbit coupling and/or electrostatic interactions on these spectra. Our findings show all elements have a single valence state (except Bi) with the allowed spin‐orbit splitting energy (Δ) for their valence of Bi 3+ , Fe 3+ , O 2− , Ba 2+ , and Ca 2+ . Here, the fraction of Bi atoms was converted into Bi‐metal Bi o , due to the Ar + ‐ion sputtering process. Interestingly, the Fe 3+ 2 p 3/2 spectra of these samples were fitted well with four Gupta–Sen multiplets, due to the combined electrostatic and spin‐orbit interactions. Particularly, the chemical pressure induced by Ca doping considerably influences the Fe 3+ 2 p 3/2 spectra of BiFeO 3 , due to the change in the FeO 6 octahedra tilting and the change in the position of Fe cations upon Ca doping. So, the edge of the valence band of the Ca‐doped BiFeO 3 materials shifted toward the Fermi level by about ~0.7 ± 0.1 eV when compared to BiFeO 3 .