実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report

課題番号 Project No.

装置責任者 Name of responsible person

2012B0211

Prof. Toru Ishigaki

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Relationship between oxide-ion conductivity and ordering

iMATERIA/(BL 20)

of oxygen vacancy in the Ln2Zr2O7 (Ln = La, Nd, Eu)

実施日 Date of Experiment

system2012/12/23-25 (48h)

実験責任者名 Name of principal investigator
Takeshi Hagiwara
所属 Affiliation
Kanagawa University試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
1) La2Zr2O7, sintered body.
2) Nd2Zr2O7, sintered body.
3) Eu2Zr2O7, submicrometer powder.

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

Samples of Ln2Zr2O7 (Ln = La, Nd, and Eu) were synthesized by a solid-state reaction method,using ZrO2 (99.2%, Tosoh Corporation), Eu2O3 (99.9%, Mitsuwa Chemicals Co.,Ltd.), Nd2O3(99.9%, Mitsuwa Chemicals Co.,Ltd.) and La2O3 (99.99%, Wako Pure Chemical Industries, Ltd.) as
starting materials.
Weighed powders were wet ball-milled for 20 h using a milling pot made of synthetic resin andresin-coated balls, and ethanol as the dispersion reagent. After drying, the powder mixtures werecalcined at 1373 K for 5 h in air. The powder samples were uniaxially-compacted under thepressure of 5 MPa and subjected to rubber press at 200 MPa, after sieving under 53 μm in meshsize. Compacts thus obtained were sintered at 1873 K for 10 h in air. The relative densities ofsintered body, which were estimated from geometric dimensions and weights, were 95.3-98.1 % of
the true densities. The sintered sample of Eu2Zr2O7 was then crushed and ground into powder forsubmicron.

12. 実験方法及び結果（つづき） Experimental method and results (continued)2-1) The results of Nd2Zr2O7 and La2Zr2O7
The time-of flight (TOF) neutron diffraction (ND) data for Ln2Zr2O7 (Ln = Nd and La) weretaken using a high throughput neutron diffractometer, iMATERIA, in BL-20 installed at theMaterial and Life Science Experimental Facility (MLF) of the Japanese Proton Accelerator
Research Complex (J-PARC). The ND data of La2Zr2O7 and Nd2Zr2O7 were collected with awide-d mode on the high resolution bank at 298, 1076, 1202, 1329, and 1455 K using a vanadium
furnace in vacuum (ca. 0.1Pa). The measurement temperatures were calibrated on the basis oflattice constants of Ln2Zr2O7 (Ln = Nd and La) obtained by high temperature X-ray diffractometry
reported in “J. Fuel Cell Sci. and Technol., 8, 051020-051024 (2011)”. The measurement time fordata collection in the 300 kW beam power was about 20 min for about 1.5g samples (sinteredbodies) contained in a 6mm diameter cylindrical vanadium cell.

Rietveld refinements for

TOF-ND data (d spacings between 0.5 and 4.0Å) were performed using the program Z-Rietveld.
The pyrochlore(P)-type structure belongs to a space group of Fd 3 m (NO.227)(Z = 8).

For origin

choice 2 and placing Ln3+ ions at the origin, i.e., 16c site (0, 0 ,0), Zr4+ ions are located at the 16dsite (1/2, 1/2, 1/2), and O2- ions at the O1(8a) site (1/8, 1/8, 1/8) and O3(48f ) site (x, 1/8, 1/8). TheO2(8b) site (3/8, 3/8, 3/8) is vacant in the completely ordered P-type structure. The diffraction
data were analyzed by using a multi-phase (i.e. Ln2Zr2O7 (Ln = Nd or La) with the completelyordered P-type structure and V) model. Figure 1 shows the result of the Rietveld analysis ofNd2Zr2O7 at 1455 K. The structural parameters estimated by Rietveld analysis of powder ND
data for Nd2Zr2O7 and La2Zr2O7 at 1455 K are summarized in Table 1.

d space / ÅFig. 1 The observed (+) and calculated (solid line) neutron diffraction patterns of Nd2Zr2O7 at
1455 K after the completion of Rietveld refinement. The curve in the bottom part of the plots
represents the difference between observed and calculated intensities (Yi obs – Yi calc).

22. 実験方法及び結果（つづき） Experimental method and results (continued)
Table 1. The results of Rietveld analysis of ND data for Nd2Zr2O7 and La2Zr2O7 at 1455 K.
Nd2Zr2O7
AtomSiteOccupancyxyz
B (Å2)
Nd
16c
1.0
0.0
0.0
0.0
0.80(2)
Zr
16d
1.0
0.5
0.5
0.5
0.49(2)
O1
8a
1.0
0.125
0.125
0.125
1.62(1)
O28b0
0.375
0.375
0.375
1.62(1)O348f
1.00.4102(1)
0.125
0.125
1.62(1)
Lattice parameter = 10.739(1) Å, RB =11.0%, RF = 13.3%, Rwp = 3.03%.
La2Zr2O7Site
Occupancyxyz
B (Å2)
La
16c
1.0
0.00.00.01.58(2)
Zr
16d
1.0
0.5
0.5
0.50.88(2)
O1
8a
1.0
0.125
0.125
0.125
1.80(2)
O2
8b0
0.375
0.375
0.375
1.80(2)
O3
48f
1.00.4189(1)
0.125
0.125
1.80(2)
Lattice parameter = 10.906(1) Å, RB =8.61%, RF = 11.7%, Rwp = 3.69%.
Although the values of Rwp for Rietveld analysis results of Nd2Zr2O7 and La2Zr2O7 were lower
than 4%, the values of RF of them were higher than 10%. To improve the refinements, we areplanning to introduce another crystal structure model, i.e. oxygen vacancies exist not only in O2(8b) site but also in O1 (8a) and O3 (48f ) sites.

2-2) The results of Eu2Zr2O7
Since the absorption cross section of the neutron for Eu is very large (a = 4530 barns), theEu2Zr2O7 sample for ND measurement was prepared by a special method.

The cylinder ofvanadium foil (diameter: ca.5mm) was put in the cylindrical vanadium cell of diameter 6 mm.
The space between the vanadium foil and vanadium cell was filled with about 0.2 g of Eu2Zr2O7powder.

The powder ND data of Eu2Zr2O7 were collected with a wide-d mode on the highresolution bank at 298 K. The measurement time for data collection in the 300 kW beam power
was about 14 h for about 0.2 g samples contained in a 6mm diameter cylindrical vanadium cell.
Rietveld refinements for TOF powder ND data (d spacing between 1.0 and 4.0Å) were performed
using the program Z-Rietveld. The Rietveld analyses were carried out assuming the following
two structure-models: Model 1 was assumed to be a completely oxygen vacancy ordered P-typestructure, where the O2(8b) site was vacancy, i.e. O2(8b) site occupancy was fixed to be 0.0, andModel 2 to be an oxygen vacancy disordered P-type structure, where the O2(8b) site was partiallyoccupied by oxide-ions.

32. 実験方法及び結果（つづき） Experimental method and results (continued)

d space / ÅFig. 2 The observed (+) and calculated (solid line) powder neutron diffraction patterns of Eu2Zr2O7
at 298 K. after the completion of Rietveld refinement. The curve in the bottom part of the plots
represents the difference between observed and calculated intensities (Yiobs – Yi calc).

Table 2. The results of Rietveld analysis of ND data for Eu2Zr2O7 at 298 K.
Eu2Zr2O7
Occupancy
xyz
1.0
0.0
0.0
0.0
1.0
0.5
0.5
0.5
1.00(1)
0.125
0.125
0.125
0.480(1)
0.375
0.375
0.375
0.920(2)0.4045(1)
0.125
0.125
Lattice parameter = 1.0558(1)nm, RB =17.0%, RF = 9.68%, Rwp = 11.2%.
AtomEuZr
O1O2O3Site
16c16d8a8b48f

B (Å2)
0.2
0.2
1.18(3)
1.18(3)
1.18(3)Figure 2 shows the final result of the Rietveld analysis of Eu2Zr2O7 on the basis of the Model 2.
The B values of Eu and Zr sites were fixed to 0.2, since they converged to very small values. TheRwp values on the basis of Models 1 and 2 were 12.5 and 11.2%, respectively. The RB and RFvalues on the basis of Model 1 were 15.2 and 10.5%, respectively. While the RB and RF values on
the basis of Model 2 were 17.0 and 9.68%, respectively. The structural parameters estimated byRietveld analysis of powder ND data for Model 2 is summarized in Table 2. To complete the lower

R values, we are planning to perform the Rietveld analysis again using the wider d range data.

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