Local Structure of Pr, Nd, and Sm Complex Oxides and Their X-ray Absorption Near Edge Structure Spectra

Abstract

Pr, Nd, and Sm L1-edge and L3-edge X-ray absorption near edge structure (XANES) spectra of their complex oxides were measured to investigate the relationship between the characteristic feature of the spectra and the local structure around the Pr, Nd, and Sm atoms. The pre-edge peak area of the L1-edge and the full width at half-maximum (fwhm) of the white line of the L3-edge XANES spectra are extracted by curve fitting analyses with one Gaussian and one cubic spline function as a background or with one arctangent and one pseudo-Voigt function, respectively. As a result, a clear correlation between the pre-edge peak area and the fwhm is found with another correlation with abstract physical parameters defined by bond angles formed with Pr, Nd, or Sm and two adjacent oxygen atoms, which represent an indicator of disorder of local configuration of the target element. This finding will open a way to estimate an average local structure of lanthanide elements by means of XANES spectroscopy.

Local Structure Study of Lanthanide Elements by X‐Ray Absorption Near Edge Structure Spectroscopy

“…Figure 9 shows Sm L 3 -edge XANES spectra of 1 mol % Sm-doped Bi 2 O 3 ÀB 2 O 3 glasses. [28] The XANES spectra are almost identical, but slightly different in their FWHMs of white line. The FWHMs were estimated by curve fitting analysis with one arctangent function and one pseudo-Voigt function in the range from 6715 to 6730 eV.…”

“…We also examined the relationship between the local structure and the L 1 ‐edge and L 3 ‐edge features of various oxides with early (Pr, Nd, Sm) and late (Ho, Er, Yb) lanthanide elements. These Ln L 1 ‐edge and L 3 ‐edge XANES spectra also show small but significant pre‐edge and white line features, and the BAA index works well with the experimental parameters from the L 1 and L 3 ‐edge XANES spectra as shown on the Ln L 1 ‐edge in Figure . Please refer to our previous paper for the corresponding L 3 ‐edge data.…”

“…To test the feasibility of the present XANES‐based approach, we measured and analysed Sm L 3 ‐edge XANES and EXAFS spectra of Sm‐doped Bi 2 O 3 −B 2 O 3 glasses. Figure shows Sm L 3 ‐edge XANES spectra of 1 mol % Sm‐doped Bi 2 O 3 −B 2 O 3 glasses . The XANES spectra are almost identical, but slightly different in their FWHMs of white line.…”

“…8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 These Ln L 1 -edge and L 3 -edge XANES spectra also show small but significant pre-edge and white line features, and the BAA index works well with the experimental parameters from the L 1 and L 3 -edge XANES spectra as shown on the Ln L 1 -edge in Figure 6. [28][29] Please refer to our previous paper for the corresponding L 3 -edge data. 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52…”

“…We started La L 1 and L 3 ‐edge XANES measurement of well‐defined La complex oxides and found a simple correlation among the pre‐edge feature at the L 1 ‐edge, the white line width on the L 3 ‐edge, and the local symmetry of the Ln species itself, and proposed a simple index, a bond angle analysis (BAA) index defined from all of the independent angles consisting of an X‐ray absorbing atom and two adjacent O atoms. Next, we successfully demonstrated generality of this strategy for Pr, Sm, Nd, and Ho, Er, Yb complex oxides. These results suggest that the empirical quantitative analysis on the Ln L 1 and L 3 ‐edge XANES spectra could be a complementary method to conventional EXAFS curve fitting analysis.…”