SPring-8, the large synchrotron radiation facility

Inquiry number

SOL-0000001206

Beamline

BL01B1 (XAFS I)

Scientific keywords

A. Sample category	inorganic material
B. Sample category (detail)	solid-state crystal, amorphous, glass
C. Technique	absorption and its secondary process
D. Technique (detail)	XAFS, EXAFS
E. Particular condition	polarization (linear), room temperature
F. Photon energy	X-ray (4-40 keV), X-ray (> 40 keV)
G. Target information	chemical state, chemical bonding, local structure, function and structure, function

Industrial keywords

level 1---Application area	mechanics, environment, Chemical product, industrial material, others
level 2---Target	catalysis
level 3---Target (detail)
level 4---Obtainable information	local structure, chemical state
level 5---Technique	XAFS, NEXAFS

Classification

A80.34 catalysis, M40.10 XAFS

Body text

In this solution, EXAFS method at Ce and Zr K-edges was applied to study local structure of CeO₂-ZrO₂ mixed oxide, oxygen storage promoters in automotive catalysts. The EXAFS method is a powerful technique to study local structure (distance, coordination number, species of neighbor atoms) of selected elements both in crystalline states and in non-crystalline states. Figure 1 shows radial structure function of Te atom after Fourier transform of Ce K-edge EXAFS spectra. Simultaneous analysis of EXAFS data set at 2 absorption edges revealed that homogeneous CeO₂-ZrO₂ solid solution (Fig. 2(c)) has high oxygen storage capacity.

Fig. 1 Radial structure function for Ce atom in CeO₂-ZrO₂ samples prepared by different methodologies.

Fig.2 Model structures of samples in Fig. 1.

[ Y. Nagai, T. Yamamoto, T. Tanaka, S. Yoshida, T. Nonaka, T. Okamoto, A. Suda and M. Sugiura, Journal of Synchrotron Radiation 8, 616-618 (2001), Fig. 3, 4, 6,
©2001 Internationa Union of Crystallography ]

Source of the figure

Bulletin from SPring-8

Bulletin title

SPring-8 Research Frontiers, 1999-2000

Page

47, 48

Technique

XAFS spectra of dense samples are taken in a transmission mode. This method is performed by measuring x-ray absorption as a function of x-ray energy around an absorption edge of a selected element. For elements from Sn to Eu in the periodic table, K-edge XAFS has advantages, such as high-spatial resolution and small contribution of multi-electron excitations, compared with L₃-edge XAFS. Acquisition time per XAFS spectrum using QXAFS mode is 10-15 min in this solution.

Source of the figure

Private communication/others

Description

講習会プレゼン資料

Required time for experimental setup

2 hour(s)

Instruments

Instrument	Purpose	Performance
XAFS Measurement System	Measurement of XAFS spectra	3.8-113 keV
Ionization Chamber	Measurement of transmission mode XAFS	concentration > 1000 ppm

References

Document name
Y. Nagai et al., Catalysis Today, 74, (2002) 225

Related experimental techniques

Questionnaire

The measurement was possible only in SPring-8. Impossible or very difficult in other facilities.
This solution is an application of a main instrument of the beamline.

Ease of measurement

Easy

Ease of analysis

Middle

How many shifts were needed for taking whole data in the figure?

Less than one shift