Deposition of hydroxyapatite on SiC nanotubes in simulated body fluid

Taguchi, Tomitsugu; Miyazaki, Toshiki*; Iikubo, Satoshi*; Yamaguchi, Kenji

Materials Science & Engineering C, 34, p.29 - 34, 2014/01

https://doi.org/10.1016/j.msec.2013.10.007

SiC nanotubes can become candidate reinforcement materials for dental and orthopedic implants due to their light weight and excellent mechanical properties. However, it has not been reported about the development of bioactive SiC materials. In this study, hydroxyapatites were found to on SiC nanotubes treated with NaOH and subsequently HCl solution after soaking in simulated body fluid. On the other hand, hydroxyapatites did not deposit on as-received SiC nanotubes, the SiC nanotubes with NHOH solution treatment and SiC bulk materials with NaOH and subsequently HCl solution treatment. Therefore, we succeeded in the development of bioactive SiC nanotubes by downsizing SiC materials to nanometer size and treating with NaOH and subsequently HCl solutions for the first time.

Local crystal structure of nano-manganese-oxide gold adsorbent

Iikubo, Satoshi*; Koyanaka, Hideki*; Shamoto, Shinichi; Takeuchi, Ken*; Kohara, Shinji*; Kodama, Katsuaki; Loong, C.-K.*

Journal of Physics and Chemistry of Solids, 71(11), p.1603 - 1608, 2010/11

https://doi.org/10.1016/j.jpcs.2010.08.011

The local crystal structure of dried and deuterated nano-manganese-oxide powder samples was studied via atomic pair distribution function analysis of X-ray and neutron powder diffraction data. The protonated sample shows ultrahigh efficiency as a gold adsorbent even from ppt-level aqueous solutions such as seawater. We show that the nano-manganese-oxide particles have an R-MnO-type local crystal structure. The possible role of the protons on the surface of the nano-particles is discussed.

Relationship between average and local crystal structure and the ferroelectric properties of a Sr-Bi-Ta-Si-O ferroelectric material

Idemoto, Yasushi*; Taniyama, Satoshi*; Iikubo, Satoshi*; Shamoto, Shinichi; Richardson, J. W.*

Journal of Physics and Chemistry of Solids, 70(8), p.1156 - 1165, 2009/08

https://doi.org/10.1016/j.jpcs.2009.06.017

Total scattering of disordered crystalline functional materials

Shamoto, Shinichi; Kodama, Katsuaki; Iikubo, Satoshi; Taguchi, Tomitsugu

Nuclear Instruments and Methods in Physics Research A, 600(1), p.229 - 231, 2009/02

https://doi.org/10.1016/j.nima.2008.11.035

As one of scientific research targets at total scattering diffractometers at J-PARC, we propose disordered crystalline functional materials. They are optical recording material, thermoelectric material, relaxor ferroelectric material, and so on. In an optical recording material, a metal-like phase should have low thermal conductivity and high electrical resistivity, simultaneously. This contradicting condition challenges material scientists to design the good functional material, which should have at least two types of crystallographic sites. One site limits the thermal conductivity, whereas the other site carries electrons or holes with high mobility. The periodic boundary condition is lost in the disorder parts. Therefore, the atomic pair distribution function (PDF) analysis is suitable to investigate the form and size of the crystalline parts as well as the disordered parts in the materials.

Magnetovolume effect in MnCuGeN related to the magnetic structure; Neutron powder diffraction measurements

Iikubo, Satoshi; Kodama, Katsuaki; Takenaka, Koshi*; Takagi, Hidenori*; Shamoto, Shinichi

Physical Review B, 77(2), p.020409_1 - 020409_4, 2008/01

https://doi.org/10.1103/PhysRevB.77.020409

Magnetic structures in an antiperovskite system MnCuGeN with a large magneto-volume effect above =0.15 have been studied by neutron powder diffraction measurement. The present neutron study revealed that not only a cubic crystal structure, but also a antiperovskite spin structure, is a key ingredient of the large magneto-volume effect in this itinerant electron system. The large magneto-volume effect is possibly ascribed to the geometrical frustration originating from the corner-shared octahedra of the antiperovskite sturucture.

Origin of the monoclinic-to-monoclinic phase transition and evidence for the centrosymmetric crystal structure of BiMnO

Belik, A. A.*; Iikubo, Satoshi; Yokosawa, Tadahiro*; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Azuma, Masaki*; Takano, Mikio*; Kimoto, Koji*; Matsui, Yoshio*; et al.

Journal of the American Chemical Society, 129(4), p.971 - 977, 2007/01

https://doi.org/10.1021/ja0664032

Structural properties of polycrystalline single-phased BiMnO samples prepared at 6 GPa and 1383 K have been studied by selected area electron diffraction (SAED), convergent beam electron diffraction (CBED), and the Rietveld method using neutron diffraction data measured at 300 and 550 K. The SAED and CBED data showed that BiMnO crystallizes in the centrosymmetric space group C2/c at 300 K. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO at 300 K melts above T= 474 K. The phase transition at 474 K is of the first order and accompanied by a jump of magnetization and small changes of the effective magnetic moment and Weiss temperature.

Local crystal structures of GeSbTe revealed by the atomic pair distribution function analysis

Shamoto, Shinichi; Kodama, Katsuaki; Iikubo, Satoshi; Taguchi, Tomitsugu; Yamada, Noboru*; Proffen, T.*

Japanese Journal of Applied Physics, Part 1, 45(11), p.8789 - 8794, 2006/11

https://doi.org/10.1143/JJAP.45.8789

Two types of optical recording crystalline material GeSbTe have been studied by neutron and X-ray powder diffraction measurements. One is the crystalline cubic-phase GeSbTe. The other is nanocrystalline-phase GeSbTe. For the nanocrystalline phase, the local crystal structure and the particle size distribution were obtained simultaneously by PDF analysis using a spherical-particle form factor. The lattice parameter is longer than that of the crystalline phase, suggesting an antimony-richer composition than the matrix. This compositional deviation would form the nanoparticle, resulting in nucleation-dominated crystal growth.

BiScO: Centrosymmetric BiMnO-type oxide

Belik, A. A.*; Iikubo, Satoshi; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Maie, Makoto*; Nagai, Takuro*; Matsui, Yoshio*; Stefanovich, S. Y.*; Lazoryak, B. I.*; et al.

Journal of the American Chemical Society, 128(3), p.706 - 707, 2006/01

https://doi.org/10.1021/ja057574u

The crystal structure of BiScO have been determined by neutron diffraction and electron diffraction measurements. All experimental results shows space group of BiScO is C2/c, which has a center of symmetry.

Effects of "stripes" on the magnetic excitation spectra of LaNdSrCuO

Ito, Masafumi*; Yasui, Yukio*; Iikubo, Satoshi*; Soda, Minoru*; Sato, Masatoshi*; Kobayashi, Akito*; Kakurai, Kazuhisa

Journal of the Physical Society of Japan, 72(7), p.1627 - 1630, 2003/07

https://doi.org/10.1143/JPSJ.72.1627

no abstracts in English

Local structure analysis of a nano-manganese oxide

Iikubo, Satoshi; Koyanaka, Hideki*; Takeuchi, Ken*; Kohara, Shinji*; Loong, C.-K.*; Kodama, Katsuaki; Shamoto, Shinichi

no journal, , 

The crystal structure of a nano-manganese oxide, which has high performance as gold adsorbent from seawater has been determined by using the atomic pair distribution function analysis of X-ray and neutron diffraction data. The results complementarily show that the nano-manganese oxide consists mainly of R-MnO.