Impact of Mn2+-Si4+ co-substitution on the electronic structure of Zn0.3Mn0.7Fe2O4 ferrites studied by X-ray photoelectron spectroscopy

Abstract

X-ray photoelectron spectroscopy (XPS) has been employed to explore the electronic structure of Zn0.3Mn0.7+xSixFe2-2xO4 (x = 0.0-0.3) ferrite series. The Si2p XPS spectra insinuated the presence of Si ions in the +4 valence state. The elemental Si-0 and suboxide SiOx are present in the system, the former showing an increase and the latter a decrease in atomic percentage upon Mn-Si substitution. It is also inferred that a fraction of Si-0 might be residing at the grain boundaries; however, more studies are required to substantiate this. The Fe2p XPS spectra stipulate that ferrous and ferric ions co-occur in the system. The ferrous ions occupy the octahedral sites while the ferric ions dwell on both the octahedral and the tetrahedral sites. The O1s spectra indicate a remarkable increase in the oxygen defects with increasing Mn-Si substitution (x). The Mn2p XPS data indicate that the Mn+2 states show an overall increasing tendency with increasing Mn-Si concentration. Also, the Mn+4/Mn+3 ratio shows an increment with an increase in Mn-Si substitution.