FE-SEM observations of multiple nanohillocks on SrTiO irradiated with swift heavy ions

Kitamura, Akane; Ishikawa, Norito; Kondo, Keietsu; Fujimura, Yuki; Yamamoto, Shunya*; Yamaki, Tetsuya*

Transactions of the Materials Research Society of Japan, 44(3), p.85 - 88, 2019/06

https://doi.org/10.14723/tmrsj.44.85

Swift heavy ions can create nanosized hillocks on the surfaces of various ceramics. When these materials are irradiated with swift heavy ions at normal incidence, each ion impact results in the formation of a single hillock on the surfaces. In contrast, irradiation at grazing incidence forms chains of multiple hillocks on the surface, for example, for strontium titanate (SrTiO). So far, chains of multiple hillocks have been investigated using atomic force microscopy (AFM). It should be noted that AFM measurements involve systematic errors of several nanometers due to the finite size of the probe tip. Consequently, it is possible that the image of one hillock may merge with that of a neighboring hillock even if the two hillocks are well separated. In contrast to AFM, field-emission scanning electron microscopy (FE-SEM) is a useful technique for obtaining higher-resolution images. In this study, we observed multiple nanohillocks on the surfaces of SrTiO using FE-SEM. Crystals of SrTiO(100) and 0.05 wt% Nb-doped SrTiO(100) were irradiated with 350 MeV Xe ions, respectively, at grazing incidence, where the angle between the sample surface and the beam was less than 2. On the SrTiO surface, a chain of periodic nanohillocks is created along the ion path. In contrast, black lines accompanied by hillocks are observed on the Nb-doped SrTiO surface.

Local disorder in proton conductor BaSnInO analyzed by neutron diffraction/ atomic pair distribution function

Igawa, Naoki; Kodama, Katsuaki; Taguchi, Tomitsugu*; Yoshida, Yukihiko*; Matsukawa, Takeshi*; Hoshikawa, Akinori*; Ishigaki, Toru*

Transactions of the Materials Research Society of Japan, 43(6), p.329 - 332, 2018/12

https://doi.org/10.14723/tmrsj.43.329

For the understanding of the crystal structural effect on the electrical properties, the local disorder in BaSnInO which is one of the excellent proton conductors for solid oxide fuel cells was estimated by using the Atomic Pair Distribution Function (PDF) analysis method with the neutron diffraction. The local structure is almost the same as the average structure which was estimated by the Rietveld analysis using the cubic crystal structure (space group, ) in the atomic distance range of 6. The PDF profile was fitted better using the tetragonal crystal structure with the space group of 4/ than those with in the range 6. Those results indicate the presence of the local disorder in the lattice. In this work, the relationship between the average and local structures of BaSnInO will be discussed.

Local structure analysis of KNbO nanocrystals with cubic shape

Yoneda, Yasuhiro; Kunisada, Ryoichi*; Chikada, Tsukasa*; Ueno, Shintaro*; Ohara, Koji*; Wada, Satoshi*

Transactions of the Materials Research Society of Japan, 43(2), p.93 - 96, 2018/04

https://doi.org/10.14723/tmrsj.43.93

KNbO nanocrystals were grown by solvothermal technique assisted by a microwave treatment. We performed high-energy X-ray diffraction to extract average and local structural parameters. The particle size can be evaluated by the Scherrer's equation. The unit cell size was reduced as the particle size increased. The local structure was found to be a rhombohedral structure, which was similar to that of the bulk KNbO.

Radiation enhanced precipitation of solute atoms in AlCu binary alloys; Energetic ion irradiation experiment and computer simulation

Mayumi, Ren*; Semboshi, Satoshi*; Okamoto, Yoshihiro; Saito, Yuichi*; Yoshiie, Toshimasa*; Iwase, Akihiro*

Transactions of the Materials Research Society of Japan, 42(1), p.9 - 14, 2017/02

https://doi.org/10.14723/tmrsj.42.9

AlCu binary alloys were irradiated with 16 MeV Au, 4.5 MeV Ni or 4.5 MeV Al ions at room temperature. Changes in surface hardness and the local atomic structure around Cu atoms were examined by using the Vickers hardness measurement and the EXAFS measurements, respectively. Some specimens were aged at 453 K and Vickers hardness was measured. The computer simulation was also performed by using the rate equation method. The hardness of irradiated specimens increased much faster than that of the aged specimens and it became larger than the maximum value of the hardness for the aged specimens. The comparison of the experimental EXAFS result with that of FEFF simulation suggests that the ion irradiation produced small Cu precipitates in the specimens. The computer simulation visualized the growth process of Cu precipitates during the irradiation, and the result qualitatively corresponds to the experimental result.

Local structure analysis of BiNaTiO, BiNaLiTiO, and 0.95BiNaTiO 0.05BaMnVO

Yoneda, Yasuhiro; Nagamoto, Takeru*; Nakai, Tomoaki*; Kobune, Masafumi*

Transactions of the Materials Research Society of Japan, 41(2), p.197 - 200, 2016/06

http://doi.org/10.14723/tmrsj.41.197

BiNaTiO (BNT) has been investigated as a lead-free piezoelectric material. We have already performed structure analysis of BNT. The average structure of BNT with low-temperature synthesis is a rhombohedral structure and it becomes a monoclinic structure as the synthesized temperature increases. Our local structure analysis indicated that the -site atoms of Bi and Na displaced toward different position depending on the lattice expansion and construction. We synthesized BNT crystals with various substitution and performed local structure analysis to examine the hypothesis. The local structure analysis revealed that the substitution effect on BNT can be explained by our hypothesis.

Local structure analysis of BaTiO modulated by Mn substitution

Yoneda, Yasuhiro; Kohara, Shinji*; Noguchi, Yuji*; Miyayama, Masaru*

Transactions of the Materials Research Society of Japan, 40(1), p.29 - 32, 2015/03

https://doi.org/10.14723/tmrsj.40.29

Barium titanate (BaTiO) with a high dielectric constant is widely used in the production of ceramic capacitors. However, during sintering large numbers of ionized oxygen vacancies and conduction electrons are created. Doping with manganese is one of several ways to confine the electrons to a small region. In Mn-doped BaTiO there exist three valence states for the manganese ions, Mn, Mn, and Mn. The Mn is nearly exactly incorporated into Ti sites and participates in the collective motion in the lattice. We performed local structure analysis by using atomic pair-distribution function (PDF) and X-ray absorption fine structure (XAFS). Figure 1 shows the obtained PDFs for pure BaTiO and 0.5%-Mn-doped BaTiO. All data collected at room temperature. Two obtained PDF patterns are well in agreement. Mn doping has hardly affected local structure.

Local structure analysis of Nb-related perovskite materials

Yoneda, Yasuhiro; Kohara, Shinji*; Nagata, Hajime*; Fu, D.*; Takenaka, Tadashi*

Transactions of the Materials Research Society of Japan, 39(4), p.455 - 458, 2014/12

https://doi.org/10.14723/tmrsj.39.455

NaNbO, KNbO, and AgNbO have rhombohedral structure at low temperatures. The phase transition depends on -site ion with NbO octahedron. NaNbO and KNbO have structural phase transition from rhombohedral to orthorhombic with increasing temperature. On the other hand, the phase transition of AgNbO occurs from rhombohedral to monoclinic. Since the rhombohedral structure is a highly ordered average structure, it tends to be subject to the influence of local randomness. We performed local structure analysis by using atomic pair-distribution function (PDF). The Nb-O bond clearly appeared in the observed distribution for NaNbO, but degraded in that for AgNbO. The difference of local structures causes different successive phase transitions for the Nb-related perovskite materials.

Fabrication and application of microcapsules including fluorescent magnetic particles for crack inspection of pipes

Ito, Fuyumi; Nishimura, Akihiko

Transactions of the Materials Research Society of Japan, 38(4), p.667 - 672, 2013/12

https://doi.org/10.14723/tmrsj.38.667

We are proposing Magnetic particle Testing (MT) using fabricated micro capsules by the hand-shake method. Here a test piece magnetized beforehand is immersed in liquid dispersed with magnetic particles. Fluorescent pigment adheres to the magnetic particles. So, MT is able to facilitate the crack visually as long as a certain amount of magnetic particles are holding the fluorescent pigment. However, separation between particle and pigment degrades transparency in liquid. Finally the hazy liquid makes difficult to find any crack. To solve this problem, we propose to use the Magnetic Particle Micro Capsule (MPMC). In addition, to applying this MPMC, the surround of the nuclear power plant should be confirmed. To confirm inside wall, the Laser Induced Breakdown Spectroscopy (LIBS) was applied.

Development of a new scanning ion microbeam analysis and imaging technique; Ion-Luminescence Microscopic Imaging and Spectroscopy (ILUMIS)

Kada, Wataru; Sato, Takahiro; Yokoyama, Akihito; Koka, Masashi; Kamiya, Tomihiro

Transactions of the Materials Research Society of Japan, 38(3), p.443 - 446, 2013/09

https://doi.org/10.14723/tmrsj.38.443

Microscopic imaging and analysis techniques are increasing its importance and being interested from the environmental research fields especially for the target with a complex elemental or chemical structures. Electron or synchrotron-radiation microbeam probes are quite poplar scanning analytical probing techniques for the imaging of such microscopic targets. On the other hand, microbeam techniques using MeV ions have also utilized for such analysis purpose with advantages in the aspect of sensitivity and S/N ratios. However, these Ion Beam Analysis (IBA) techniques like PIXE (Particle Induced X-ray Emission) do not have enough sensitivity in the chemical-state analysis. This limits the application area of IBA techniques compared to the other beam probes. In this study, an new ion microbeam technique with Microscopic by spectroscopic analysis of IL was developed and combined with micro-PIXE system for the simultaneous analysis and imaging of chemical-state distribution in microscopic targets. Spectroscopy of IL from the National Institute of Environmental Science (NIES) aerosol standards was first achieved to visualize chemical state distribution in such microscopic analytical targets with spatial resolution of 1m.

Fabrication of micropatterns on teflon by proton beam writing and nitrogen ion beam irradiation

Kitamura, Akane; Sato, Takahiro; Koka, Masashi; Kamiya, Tomihiro; Kobayashi, Tomohiro*

Transactions of the Materials Research Society of Japan, 38(1), p.101 - 104, 2013/03

https://doi.org/10.14723/tmrsj.38.101