EELS Investigations of Different Niobium Oxide Phases

Abstract

Electron energy loss spectra in conjunction with near-edge fine structures of purely stoichiometric niobium monoxide (NbO) and niobium pentoxide (Nb2O5) reference materials were recorded. The structures of the niobium oxide reference materials were checked by selected area electron diffraction to ensure a proper assignment of the fine structures. NbO and Nb2O5 show clearly different energy loss near-edge fine structures of the Nb-M4,5 and -M2,3 edges and of the O-K edge, reflecting the specific local environments of the ionized atoms. To distinguish the two oxides in a quantitative manner, the intensities under the Nb-M4,5 as well as Nb-M2,3 edges and the O-K edge were measured and their ratios calculated. k-factors were also derived from these measurements.

Microstructural control of new intercalation layered titanoniobates with large and reversible d-spacing for easy Na + ion uptake

“…The Nb M 5,4 edges represent the electron transition from Nb 3d levels to unoccupied Nb 4f and 5p levels. Nb ELNES spectra also show the same trend as that of titanium in the shift of the M 5,4 edges to the lower energy position after sodiation, which is attributed to the decrease in the oxidation state of Nb 5+ ( 53 ). Bach et al .…”

“…Bach et al . ( 53 ) performed the EELS investigation of Nb 2 O 5 (+5), NbO 2 (+4), and NbO (+2). In comparison with Nb ELNES spectra in the reference, the delayed maximum shape after sodiation is similar to that of NbO 2 (+4), which is an evidence for the reduction of niobium.…”

Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by transmission electron microscopy and electron energy loss spectroscopy

“…28 Three spectra for each region were added after the background subtraction with log-polynomial function. 29 Thickness of the sample in the region of interest was estimated to be 41 nm from the Log-Ratio Method. 28 The linear relationship between the chemical shift of Medge onset and niobium valence can be used to determine the niobium oxidation state.…”

Quantitative use of electron energy-loss spectroscopy Mo-M2,3 edges for the study of molybdenum oxides

“…In 1987, Hofer has shown that M 4,5 edges can be used for elemental quantification of MoO 3 by determining the k-factors [20], and the same method was applied more recently to quantify niobium oxides [21,22]. The main drawback of using 4d-TM-M 4,5 edges lies however in the delayed maximum that hinders the precise determination of the edge offset and thus has a detrimental effect on the precision of the elemental quantification.…”