Photon Factory Activity Report 2004 #22 Part B (2005)
Instrumentation and TechniqueNE1/2004G312

Kβ intensity ratios for Gd and Tb oxides and fluorides
Masaaki HARADA1, Masahiko SHOJI2, Hiroshi KAWATA3, and Kenji SAKURAI*2
1
Fukuoka University of Education, Munakata, Fukuoka 811-4192, Japan
2
National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan3
Photon Factory, Tsukuba, Ibaraki 305-0801, Japan
Introduction
It has become important to develop methods forobserving the chemical environments of gadolinium andterbium in light of recent strong demand related tonanotechnology applications. In this report, the use of Kβ
X-ray fluorescence spectra has been examined.
Experimental
The samples measured were 10 mm diameter x 5mm thick pellets of Gd and Tb compounds (metal, oxide,and fluoride). They were mounted in the vacuum
chamber that is usually used for Compton scattering
measurements at the beamline. Energy-dispersive X-ray
fluorescence (XRF) spectra were collected from 90 deg
direction by a Ge detector (Canberra) and a digital signal
processor (ORTEC DSPEC Jr). The energy of theincident X-rays was set at 69 keV.
Results and Discussion
Figure 1 shows X-ray fluorescence spectra ofterbium oxide (Tb4O7). The accumulation time (real time)was 7200 sec. and the counting rate was 1.3 k counts/sec.
One can see characteristic Tb K-lines as well as theirescape and sum peaks. The Kβ peaks measured werehigher than those of Kα, because an attenuator (copperplate, 1.5mm thick) was placed in front of the detector.
The energy resolution was ca 400 eV at around Tb Kβ1.
The intensity ratio between the Kβ1 and Kβ2 lines(see the inset of Fig.1) is basically constant, and is around0.75, as long as the sample is thick enough, though themass absorption coefficient differs for these two energies.
6Kα5Intensity (counts)

104Kβ2

EscapeKβ2

1010

Kβ1

5052

Pb K

Pb L

Sum2

Table 1 Summary of the intensity ratio Kβ2/Kβ1 for Gd andTb samples.
Metal

Gd
0.75715±0.00031

Tb
0.74719±0.00028

Fluoride
Oxide

0.75609±0.00027
0.75620±0.00037

0.74605±0.00031
0.74406±0.00050

100.0Excitation

310References[1] M. Harada and K. Sakurai, Photon Factory Activity
Report #20, 286 (2002); #21, 268 (2003).
*sakurai@yuhgiri.nims.go.jp

Kβ1/(Kβ1+Kβ2)

10However, the intensity ratio can change slightly
depending on the chemical environment [1]. Some results
for gadolinium and terbium are listed in Table 1. Theintensity ratio Kβ2/Kβ1 grows larger for metals rather thanoxides and fluorides in the case of both gadolinium andterbium. Figure 2 shows the differences among thosesamples more clearly. Here, the net intensity ratios ofΚβ1 to (Κβ1 + Κβ2) for fluorides and oxides were plotted
as a percentage to those of metals. It has been found that
there is only small difference between the fluoride andoxide for gadolinium, but some changes are observed forterbium. It is interesting to note when considering thepresent results that they correspond to the order of theformal oxidation number, i.e., 0, +3, and +3.5 for terbium
metal, fluoride, and oxide, respectively. Although theresearch is in the preliminary stage, further experiments
to collect data for many different compounds are inprogress. Some theoretical discussion is also important.
The authors would like to thank Professor N. Shiotani forhis kind cooperation.

10GdTb99.5

Compton1

1099.0010204060
Energy (keV)

Figure 1 The XRF spectra of Tb4O7 pellet.

80

100

Fluoride
Oxide
Figure 2 The relative changes of Kβ intensity ratios forfluorides and oxides in comparison to the metals. The
left (red) and right (green) bars indicate gadolinium andterbium, respectively.

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