JOPSS - Search Results

Journal Articles

Study of annealing effect on crystal and local structures of doped zirconia using multi probe

Ito, Takanori*; Mori, Masashi*; Inukai, Manabu*; Nitani, Hiroaki*; Yamamoto, Takashi*; Miyanaga, Takashi*; Igawa, Naoki; Kitamura, Naoto*; Ishida, Naoya*; Idemoto, Yasushi*

Photon Factory News, 33(1), p.18 - 24, 2015/05

http://pfwww.kek.jp/publications/pfnews/33_1/saikin1.pdf

The effect of the annealing on the crystal and local structures of doped zirconia was investigated by multi-probe technique using synchrotron X-ray and neutron diffraction, and first principles calculation. It was revealed that the annealing process enhances the periodic distortion of some zirconia compounds by Rietveld/ maximum entropy methods applied to the SR-X-ray and neutron diffractions. In addition, the combined X-ray absorption spectroscopy and first-principles calculations results showed the ZrO $_{8}$ polyhedra in zirconia were distorted by the annealing. Those results indicate that the degradation of oxide ionic conductivity by the annealing was related to the periodic distortion in zirconia.

Journal Articles

Effect of annealing on crystal and local structures of doped zirconia using experimental and computational methods

Ito, Takanori*; Mori, Masashi*; Inukai, Manabu*; Nitani, Hiroaki*; Yamamoto, Takashi*; Miyanaga, Takashi*; Igawa, Naoki; Kitamura, Naoto*; Ishida, Naoya*; Idemoto, Yasushi*

Journal of Physical Chemistry C, 119(16), p.8447 - 8458, 2015/04

https://doi.org/10.1021/jp5117118

Times Cited Count：18 Percentile：50.75(Chemistry, Physical)

The effects of the annealing process on the crystal and local structures of the doped zirconia were investigated by Rietveld refinements of synchrotron X-ray and neutron diffraction, maximum entropy method (MEM), X-ray absorption spectroscopy (XAS) and first principles calculation (FPC). This study reveals that the crystal structures of the sintered and annealed ((Zr $_{0.85}$ Y $_{0.15}$ )O $_{2}$ and (Zr $_{0.81}$ Sc $_{0.18}$ Ce $_{0.01}$ )O $_{2}$ ) are cubic with the space -3 having large atomic displacement parameters (). For the annealed (Zr $_{0.85}$ Y $_{0.15}$ )O $_{2}$ , the values reduce, and the electrons around the Zr/oxide ion sites gather at the center of each site. On the other hand, the annealed (Zr $_{0.81}$ Sc $_{0.18}$ Ce $_{0.01}$ )O $_{2}$ shows the opposite tendency to that of the annealed (Zr $_{0.85}$ Y $_{0.15}$ )O $_{2}$ .

Journal Articles

Crystal structural analysis of solid oxide fuel cells using the synchrotron X-ray and neutron diffraction method

Ito, Takanori*; Igawa, Naoki; Homma, Tetsuo*

Supuringu-8 No Kokido Hoshako O Riyoshita Gurin Enerugi Bunya Niokeru Denchi Kaihatsu, p.104 - 112, 2014/02

Functional materials consist of many elements and therefore have complex crystal structure. Synchrotron X-ray and neutron scattering facilities are powerful tools to investigate the crystal structural information of those materials. Here we make an introduction to the crystal analysis method by the synchrotron X-ray and neutron diffraction applying to the solid oxide fuel cells.

Journal Articles

Protonic conduction, crystal and electronic structures of La $_{0.9}$ Ba $_{1.1}$ Ga $_{0.95}$ Mg $_{0.05}$ O $_{4-delta}$

Hamao, Naoki*; Kitamura, Naoto*; Ito, Takanori*; Igawa, Naoki; Idemoto, Yasushi*; Daido, Hiroyuki; Kaku, Masanori*; Kubodera, Masakazu*

Solid State Ionics, 253, p.123 - 129, 2013/12

https://doi.org/10.1016/j.ssi.2013.09.021

Times Cited Count：3 Percentile：15.44(Chemistry, Physical)

La $_{0.9}$ Ba $_{1.1}$ Ga $_{0.95}$ Mg $_{0.05}$ O $_{4-delta}$ which is one of the candidates for solid electrolyte of solid oxide fuel cell was synthesized by means of a conventional solid-state reaction, and investigated by conductivity measurements, the Rietveld and maximum entropy method analyses using neutron and synchrotron X-ray diffraction data. Conductivity measurements indicated that simultaneous Ba and Mg substitutions for LaBaGaO $_{4}$ were effective way to improve the protonic conductivity. From the Rietveld and maximum entropy method analyses, it was confirmed that La $_{0.9}$ Ba $_{1.1}$ Ga $_{0.95}$ Mg $_{0.05}$ O $_{4-delta}$ kept the same crystal structure as LaBaGaO $_{4}$ even at elevated temperature, i.e. 1000 K, and that protons existed around the O3 site and formed hydrogen bonds. It is also found that oxygens in LaBaGaO $_{4}$ -based samples formed Ga-O $_{4}$ tetrahedra, and the bonding strength was varied by the partial substitutions.

Journal Articles

Study of oxygen ion diffusion in (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33-delta}$ through neutron diffractions at 300 and 720 K

Ito, Takanori*; Hirai, Takene*; Yamashita, Junichi*; Watanabe, Shoji*; Kawata, Etsuya*; Kitamura, Naoto*; Idemoto, Yasushi*; Igawa, Naoki

Physica B; Condensed Matter, 405(8), p.2091 - 2096, 2010/04

https://doi.org/10.1016/j.physb.2010.01.109

Times Cited Count：15 Percentile：55.02(Physics, Condensed Matter)

We analyze the mechanism of oxygen ion diffusion in (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33-delta}$ by using the Rietveld refinement, the maximum entropy method (MEM) analysis, and MEM-based pattern fitting (MPF) with neutron diffractions at 300 and 720 K. We speculate that when $_{rm aniso}$ and neutron scattering density of O1(4) site with a large number of vacancies metamorphose into that with anisotropy directed toward the O1(4) and O2(8) sites at 720 K, the oxygen ions diffuse along the paths between O1(4) and O1(4), and O1(4) and O2(8).

Journal Articles

Study of mechanism of mixed conduction due to electrons and oxygen ions in (La $_{0.75}$ Sr $_{0.25}$ )MnO $_{3.00}$ and (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ through rietveld refinement and MEM analysis

Ito, Takanori*; Shirasaki, Saori*; Fujie, Yoshinori*; Kitamura, Naoto*; Idemoto, Yasushi*; Osaka, Keiichi*; Hirosawa, Ichiro*; Igawa, Naoki

Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 77(2), p.161 - 168, 2009/02

https://doi.org/10.5796/electrochemistry.77.161

Times Cited Count：3 Percentile：8.22(Electrochemistry)

We analyzed the mechanism of mixed conduction due to electrons and oxygen ions in (La $_{0.75}$ Sr $_{0.25}$ )MnO $_{3.00}$ and (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ through the Rietveld refinement and maximum entropy method analyses of neutron and synchrotron X-ray diffractions. It was found that Mn-O plane in (La $_{0.75}$ Sr $_{0.25}$ )MnO $_{3.00}$ has a strong, isotropic covalent bond that enables conduction of electrons. The (Co, Fe)-O2 plane with a covalent bond and a low concentration of oxygen vacancies in (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ can also conduct electrons. On the other hand, the (Ba, Sr)-O1 plane in (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ , which has a high concentration of oxygen vacancies, large isotropic displacement parameter, and a strong ionic bond, is responsible for the diffusion of oxygen ions.

Journal Articles

Determination of crystal structure and charge density of (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ by Rietveld refinement and maximum entropy method analysis

Ito, Takanori*; Nishida, Yuki*; Tomita, Aya*; Fujie, Yoshinori*; Kitamura, Naoto*; Idemoto, Yasushi*; Osaka, Keiichi*; Hirosawa, Ichiro*; Igawa, Naoki

Solid State Communications, 149(1-2), p.41 - 44, 2009/01

https://doi.org/10.1016/j.ssc.2008.10.020

Times Cited Count：36 Percentile：76.96(Physics, Condensed Matter)

The crystal structure and charge density of (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ were investigated by the Rietveld refinement method and the maximum entropy method by using neutron and synchrotron X-ray diffraction. The crystal structure was refined by using the split atom model to cation sites with the space group, . The site occupancies of O1(4) and O2(8) sites were 0.59 and 0.87, respectively. It was found that the (Co, Fe)-O2 plane in the sample has anisotropic covalent and ionic bands, and that the (Ba, Sr)-O1 bond was ionic with a low charge density.

Oral presentation

Study of electron-oxide ion mixed conduction in SOFC cathode materials by MEM

Ito, Takanori*; Yokote, Takenori*; Kitamura, Naoto*; Idemoto, Yasushi*; Sakuma, Takashi*; Takahashi, Haruyuki*; Igawa, Naoki

no journal, ,

The investigation and development of the cathode materials are one of the major subjects to decrease the operation temperature for solid oxide fuel cell. In this study, we measured the neutron and synchrotron X-ray diffraction of La $_{0.73}$ Sr $_{0.24}$ MnO $_{3}$ and (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{3-delta}$ . We discuss the mechanism of the electron-oxide ion mixed conduction from the Rietveld and the maximum entropy method analyses.

Oral presentation

Crystal structure of SOFC cathode materials by neutron and synchrotron X-ray diffraction

Ito, Takanori*; Yokote, Takenori*; Kitamura, Naoto*; Idemoto, Yasushi*; Sakuma, Takashi*; Takahashi, Haruyuki*; Igawa, Naoki

no journal, ,

Perovskite-type oxides with electron-oxide ion mixed conduction are attractive materials as a cathode for solid oxide fuel cell. Although (La,Sr)MnO $_{3}$ is applied for this purpose, (Ba,Sr)(Co,Fe)O $_{3-delta}$ has much attention because it has lower operation temperature. In this study, we carried out the neutron and synchrotron X-ray diffraction study on those materials, and discuss the difference in crystal structure including the nuclei and electron distribution on the transition metal-oxygen plain in the crystal from the results of the Rietveld and the maximum entropy method analyses.

Oral presentation

Effect of annealing on crystal structure of SOFC electrolyte materials by in-situ neutron diffraction

Ito, Takanori*; Hirai, Takene*; Wang, Z.*; Mori, Masashi*; Igawa, Naoki

no journal, ,

We investigate the effect of annealing on the crystal structure of the solid oxide fuel cell electrolyte by neutron diffraction study with the Rietveld/maximum entropy method analyses. We observed the high nuclear scattering length density distribution of oxygen on the (400) plane of as sintered scandium and cerium oxide doped zirconia measured at 700 K. It was founded that those spread region became lower by the annealing at 600 $^{circ}$ C for 1000h.

Oral presentation

Effect of anealing on crystal structure of SOFC electrolyte materials by in-situ neutron diffraction

Ito, Takanori*; Hirai, Takene*; Wang, Z.*; Mori, Masashi*; Igawa, Naoki

no journal, ,

The crystal structures of annealed SOFC, (Zr,Y)O $_{2-delta}$ , (Zr,Sc,Ce)O $_{2-delta}$ were analyzed out by the Rietveld/maxmum entropy method applying the in-situ neutron powder diffraction at 600 and 800 $^{circ}$ C. We found that the nuclear distribution region became narrow by the annealing at 600 $^{circ}$ C for 1000 h.

Oral presentation

Long annealing effects of (La, Sr)(Co, Fe)O $_{3-delta}$ for solid oxide fuel cells cathode materials

Ito, Takanori*; Kurumada, Masamori*; Nishida, Yuki*; Hirai, Takene*; Igawa, Naoki

no journal, ,

We have studied the change of oxygen behavior using by neutron diffractions before and after annealed (La,Sr)(Co,Fe)O $_{3-delta}$ (LSCF) synthesized from high or low purity raw materials. The oxygen neutron scattering length density of the high purity LSCF concentrated to the 18 site after annealing according to results of the Rietveld refinement and the maximum entropy method. On the other hand, For one of the low purity LSCF, No marked changes were seen. These results suggest that oxygen concentrate to the stable site in the high purity LSCF, on the other hand, the stability of the oxygen in low purity LSCF did not change by annealing.

Presentation/Publication Type

Journal/Book Title

Meeting title

First Author

Keyword

Language

Publication Year

Held year of conference

Study of annealing effect on crystal and local structures of doped zirconia using multi probe

Effect of annealing on crystal and local structures of doped zirconia using experimental and computational methods

Crystal structural analysis of solid oxide fuel cells using the synchrotron X-ray and neutron diffraction method

Protonic conduction, crystal and electronic structures of La $_{0.9}$ Ba $_{1.1}$ Ga $_{0.95}$ Mg $_{0.05}$ O $_{4-delta}$

Study of oxygen ion diffusion in (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33-delta}$ through neutron diffractions at 300 and 720 K

Study of mechanism of mixed conduction due to electrons and oxygen ions in (La $_{0.75}$ Sr $_{0.25}$ )MnO $_{3.00}$ and (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ through rietveld refinement and MEM analysis

Determination of crystal structure and charge density of (Ba $_{0.5}$ Sr $_{0.5}$ )(Co $_{0.8}$ Fe $_{0.2}$ )O $_{2.33}$ by Rietveld refinement and maximum entropy method analysis

Study of electron-oxide ion mixed conduction in SOFC cathode materials by MEM

Crystal structure of SOFC cathode materials by neutron and synchrotron X-ray diffraction

Effect of annealing on crystal structure of SOFC electrolyte materials by in-situ neutron diffraction

Effect of anealing on crystal structure of SOFC electrolyte materials by in-situ neutron diffraction

Long annealing effects of (La, Sr)(Co, Fe)O $_{3-delta}$ for solid oxide fuel cells cathode materials