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
課題番号 Project No. 2012B0217

提出日 Date of ReportFebruary 1, 2013
装置責任者 Name of responsible person
Toru Ishigaki

実験課題名 Structural Origin of Large Oxygen Permeability in

装置名 Name of Instrument/（BL No.）

the K2NiF4-Type Mixed and Ionic Conductors

BL-20

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Masatomo Yashima

December 25-27, 2012

所属 Affiliation

January 14, 18, 2013

Department of Chemistry and Materials Science, Graduate
School of Science and Engineering,Tokyo Institute of Technology
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.

A A' BO4- and ABO3-based materials (A: large cations such as rare earth La, Ce, Pr, Nd, Y and Ba, Sr, Ca; B:
smaller cations as In, Si, Sn, Ge, Ga, Mn, Fe, Co).

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.

Experimental methods

Neutron powder diffraction data of AA' BO4- and ABO3-based materials were measured atroom temperature and at high temperatures by a high-resolution neutron powder
diffractometer iMateria installed at the beam line BL20 of J-Parc facility, Japan. The sinteredor the powder samples were introduced into 6 mm vanadium sample holders and were used
for the diffraction measurements. The diffraction data were analyzed by the Rietveld methodwith the computer program Z-Rietveld.
Experimental results

The crystal structure of BaNdInO4 has previously unknown structural type and we haverecently solved its crystal structure from the powder X-ray diffraction data. The Rietveld
analysis of BaNdInO4 was initially carried out using the structural model obtained by thepowder X-ray diffraction analysis. However, the analysis did not give a good quality fitting as
shown in the Figure 1a (Rwp = 0.1350 and RB = 0.1767).
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2. 実験方法及び結果（つづき） Experimental method and results (continued)

Because some diffraction peaks could not be explained by the initial structural model, the unit
cell parameters were re-examined and it was found that the correct structure has a doubled
unit cell of the initial model. Using a new structural model, a good quality fitting was finallyachieved with Rwp = 0.0417 and RB = 0.0441 (Figure 1b). Neutron diffraction profiles include
useful information on oxygen, because the scattering ability of the oxygen nucleus (amplitude ofcoherent scattering length) is relatively large and independent of diffraction angle. In the present
case, both the initial and final structural models of BaNdInO4 have almost same atomic positions
for the metal atoms and small difference could be recognized in the oxygen atomic positions.
Because of the low scattering power for oxygen in the X-ray diffraction data, it was very difficult todetermine the correct crystal structure only from the powder X-ray diffraction data. Thus, thepresent study has clearly showed that the neutron powder diffraction experiments provide thecritical information for a correct crystal structure of the metal oxide materials. Finally, the validityof the analyzed crystal structure of BaNdInO4 was confirmed from bond valence sums (BVS). The
BVSs of the cations were calculated to be 3.00 for In, 1.75 for Ba and 2.95 for Nd. The formal
charges of In, Ba and Nd are +3, +2 and +3, and well agree with the calculated BVSs.
In the crystal structure of BaNdInO4, the Ba and In construct the two-dimensional slabs (BaInOslabs) which are interleaved with the two-dimensional NdO layers (Figure 2). Such layered
structure could have an advantage for the oxide-ion conduction and we are currently carrying out
the electrical-conductivity measurements with the aim for the application as a mixed oxide-ionconductor.

Figure 1. Rietveld plot of BaNdInO4 with (a) the initial wrong structural model and (b) the final
correct structural model.

Figure 2. Refined crystal structure of BaNdInO4.

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