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
2015/2/16

課題番号 Project No.

装置責任者 Name of responsible person

2014A0175

Takashi Kamiyama

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Crystal structures at high temperature of layered gallate-based

SuperHRPD/BL08

oxide-ion conductors with the Melilite structure

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2014/6/12 - 2014/6/14

Yasushi Idemoto

2014/12/3 - 2014/12/5

所属 Affiliation
Tokyo University of Science
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.

La1+xSr1-xGa3O7+,pellet2. 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 method
La1+xSr1-xGa3O7+ (x=0~0.62) were synthesized by a conventional solid-state reaction method using
La2O3, SrCO3 and Ga2O3 as starting materials. Phase identifications of these samples were performed
preliminarily by powder X-ray diffraction measurements, and the metal compositions were confirmed byinductively-coupled plasma (ICP) technique. Conductivities of their sintered pellets were measured at thetemperature range of 300~900 oC by an AC two probe method. From dependencies of the conductivities on
oxygen partial pressure, predominant oxide-ion conductions were confirmed in the case of La1+xSr1-xGa3O7+
with x > 0.
In order to investigate crystal structures at elevated temperature, neutron diffraction patterns wererecorded at 500 oC in addition to room temperature by SuperHRPD. In this experiment, a sintered pellet of eachsample was loaded in a V can, and then the can was mounted in a furnace. The obtained data (BS bank) wereanalyzed on the basis of the Rietveld method and the maximum-entropy method by using the Z-Rietveld andZ-MEM.
12. 実験方法及び結果（つづき） Experimental method and results (continued)
Results
A Rietveld refinement pattern of La1.5Sr0.5Ga3O7.25 at 500 oC is presented in Fig. 1. In the analysis, we
assumed a space group of the crystal structure as P-421m (the Melilite-type structure), and refined atomic
positions and displacement parameters of all the elements. Site occupancies were fixed taking the metalcomposition and the nominal valences into account. It was demonstrated that the sample had a single phase of
the Melilite structure even at high temperature as well as room temperature although the lattice parameters
became larger due to thermal expansion.
Figure 2 shows a 2D image of nuclear-density distribution [(001) plane] of the sample at 500 oC. In thisfigure, the O4 represent interstitial oxide ions which can be considered as conduction species. It was found thatthe nuclear density of O4 was dispersed anisotropically within the (001) plane. This results indicates that theinterstitial oxide ions can diffuse along with this plane, i. e. the Ga-O4 tetrahedral network.

Fig. 1 Rietveld refinement pattern of La1.5Sr0.5Ga3O7.25 at 500 oC (S. G. P-421m). Plus marks show observed
neutron diffraction intensities, and a solid line represents calculated intensities. Vertical marks indicate positionsof the Bragg reflections. A curve at the bottom is a difference between the observed and calculated intensities.
R-factors were R wp=2.16 % and Re=1.57 %.

Fig. 2 Nuclear-density distribution [(001) plane] of La1.5Sr0.5Ga3O7.25 at 500 oC.

2