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Chen, Y.*; Feng, X.*; Kasukabe, Yoshitaka*; Yamamoto, Shunya; Yoshikawa, Masahito; Fujino, Yutaka*
Journal of Alloys and Compounds, 577(Suppl.1), p.S18 - S24, 2013/11
Times Cited Count：2 Percentile：17(Chemistry, Physical)Epitaxial transformation processes of titanium films due to Nitrogen-implantation have been clarified through in-situ observations by using transmission electron microscope(TEM)and electron energy loss spectroscope, along with molecular orbital calculations. The N
ions with 62 keV are implanted into as-deposited Ti films which consist of hcp-Ti and TiH
with preferred orientations, in the 400 kV analytic high resolution TEM combined with ion accelerators at JAEA Takasaki. Thus, titanium nitride (TiN
) films with preferred orientations are epitaxially formed by the inheritance of partial atomic arrangement of hcp-Ti or TiH in as-deposited Ti films and by the occupation of octahedral sites by N atoms, which elucidates that epitaxial transformation of hcp-fcc Ti sublattices occurs.
Kasukabe, Yoshitaka*; Shimoda, Hiroyuki*; Chen, Y.*; Yamamoto, Shunya; Yoshikawa, Masahito; Fujino, Yutaka*
Nuclear Instruments and Methods in Physics Research B, 315, p.131 - 135, 2013/11
Times Cited Count：1 Percentile：11.54(Instruments & Instrumentation)Epitaxial transformation phenomena of titanium films due to Nitrogen-implantation have been clarified through in-situ observations by using transmission electron microscope(TEM)and electron energy loss spectroscope (EELS), along with molecular orbital calculations. The N
ions with 62 keV are implanted into as-deposited Ti films which consist of hcp-Ti and TiH
with preferred orientations, in the 400 kV analytic high resolution TEM combined with ion accelerators at JAEA Takasaki. The result of EELS measurements indicates that the hcp-fcc transformation occurs preferentially above a critical concentration ratio, N/Ti 
0.25. This means that above the N/Ti 0.25, the invasion of implanted N atom to the N-unoccupied octahedral site in the neighboring unit cell next to the N-occupied one in hcp-Ti occurs preferentially, and induces the growth of nucleus of the hcp-fcc transformation.
Kasukabe, Yoshitaka*; Chen, Y.*; Yamamoto, Shunya; Yoshikawa, Masahito; Fujino, Yutaka*
e-Journal of Surface Science and Nanotechnology (Internet), 9, p.191 - 198, 2011/04
The purpose of this work is to study changes of the crystallographic and electronic structures of Ti films by heating and by nitriding during N-implantation into Ti films, using in-situ transmission electron microscope equipped with the instrument for electron energy loss spectroscopy, and then to clarify the atomistic nitriding processes of Ti thin films due to the N-implantation with the aid of self-consistent charge discrete variational X
molecular orbital calculations. It is clarified that the maximum concentration of N in Ti films during the N-implantation and the change of electronic structures near the fermi level, respectively, depend on the implantation temperature and the ratio of N/Ti in Ti films. Furthermore, taking into account the bonding interaction of Ti sublattices with ligand N atoms, the transformation mechanisms between hcp-Ti and fcc-Ti sublattices due to the implantation of N atoms are discussed.
Kasukabe, Yoshitaka*; Watanabe, Yohei*; Yamamoto, Shunya; Yoshikawa, Masahito; Fujino, Yutaka*
e-Journal of Surface Science and Nanotechnology (Internet), 7, p.625 - 632, 2009/04
Titanium nitrides (TiN) are non-stoichiometric compounds and show covalent properties as well as metallic and ionic properties, which make them fascinating for both fundamental research and technological applications. The purpose of this work is to study changes of the crystallographic and electronic structures of Ti films by heating and by nitriding during N-implantation into Ti films separated from NaCl(001) substrates, using in-situ transmission electron microscope (TEM) equipped with the instrument for electron energy loss spectroscopy (EELS), and then to clarify the atomistic nitriding processes of Ti thin films due to the N-implantation with the aid of molecular orbital calculations. The present calculations throw light on the hcp-fcc transformation mechanism between fcc-Ti sublattices and hcp sublattices due to the release of H atoms or due to the implantation of N atoms, taking into account the bonding interaction of Ti sublattices with ligand H or N atoms.
Kasukabe, Yoshitaka*; Nishida, Shinsaku*; Yamamoto, Shunya; Yoshikawa, Masahito; Fujino, Yutaka*
Applied Surface Science, 254(23), p.7942 - 7946, 2008/09
Times Cited Count：8 Percentile：37.3(Chemistry, Physical)In order to clarify atomistic growth processes of TiN films due to ion implantation, in-situ observations by using transmission electron microscope and electron energy loss spectroscope at JAEA-Takasaki have been carried out, along with composition analysis and with the characterization of the electronic structure by molecular orbital calculation. The characterization of electronic structure of Ti films before and after implantation indicates that octahedral sites of hcp-Ti with larger space have higher electron density, which leads to the invasion of implanted ions into octahedral sites, and that the hcp-fcc transformation is induced by the shear in 
010
direction on (001) plane, promoted by the forming of 
-type covalent bonds mainly consisted of hybridized orbitals due to combination of Ti3d and N2p, and by the weakening of Ti-Ti bonds.
Kasukabe, Yoshitaka*; Yamamura, Tsutomu*; Wang, J. J.*; Nishida, Shinsaku*; Yamamoto, Shunya; Yoshikawa, Masahito
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 146, 2007/02
no abstracts in English
Kasukabe, Yoshitaka*; Wang, J. J.*; Yamamura, Tsutomu*; Fujino, Yutaka*; Yamamoto, Shunya; Yoshikawa, Masahito
Materia, 45(1), p.23 - 31, 2006/01
no abstracts in English
Kasukabe, Yoshitaka*; Wang, J. J.*; Yamamura, Tsutomu*; Yamamoto, Shunya; Fujino, Yutaka*
Thin Solid Films, 464-465, p.180 - 184, 2004/10
Times Cited Count：9 Percentile：43.98(Materials Science, Multidisciplinary)no abstracts in English
Wang, J. J.*; Kasukabe, Yoshitaka*; Yamamura, Tsutomu*; Yamamoto, Shunya; Fujino, Yutaka*
Thin Solid Films, 464-465, p.175 - 179, 2004/10
Times Cited Count：1 Percentile：7.12(Materials Science, Multidisciplinary)no abstracts in English
Kasukabe, Yoshitaka*; Yamamura, Tsutomu*; Wang, J. J.*; Nishida, Shinsaku*; Yamamoto, Shunya; Yoshikawa, Masahito
no journal, ,
no abstracts in English
