Oxidation of TiAl surface with hyperthermal oxygen molecular beams

Hashinokuchi, Michihiro*; Tode, Mayumi*; Yoshigoe, Akitaka; Teraoka, Yuden; Okada, Michio*

Applied Surface Science, 276, p.276 - 283, 2013/07

https://doi.org/10.1016/j.apsusc.2013.03.082

A Chemical-state-specific study of the composition of the natural oxide layer of VCrTi

Harries, J.; Teraoka, Yuden; Tode, Mayumi; Yoshigoe, Akitaka

Applied Physics Express, 5(3), p.031802_1 - 031802_3, 2012/03

https://doi.org/10.1143/APEX.5.031802

Effect of the soft X-rays on highly hydrogenated diamond-like carbon films

Kanda, Kazuhiro*; Yokota, Kumiko*; Tagawa, Masahito*; Tode, Mayumi; Teraoka, Yuden; Matsui, Shinji*

Japanese Journal of Applied Physics, 50(5), p.055801_1 - 055801_3, 2011/05

https://doi.org/10.1143/JJAP.50.055801

Recently, the irradiation of soft X-ray synchrotron radiation (SR) to highly-hydrogenated diamond-like carbon (H-DLC) films in vacuum results in the desorption of hydrogen and the increase of film density, hardness and refractive index. In this study, we investigated SR irradiation effects on the H-DLC with different hydrogen contents. The H-DLC thin films were deposited on an Si wafer with 200 nm thickness by an amplitude-modulated radio frequency plasma chemical vapor deposition method. The SR irradiation was carried out at NewSUBARU BL6. The SR has a continuous spectrum from IR to soft X-ray, which is lower than 1 keV. The hydrogen content dependence on SR dose was estimated using elastic recoil detection analysis (ERDA) and Rutherford backscattering (RBS) techniques. The hydrogen content was kept constant in the low-hydrogenated DLC film, while that in the high-hydrogenated DLC film decreased exponentially with soft X-ray dose.

The Study of oxidation on TiAl surface with photoemission spectroscopy in conjunction with synchrotron radiation

Hashinokuchi, Michihiro*; Sumimoto, Yuichi*; Tode, Mayumi; Harries, J.; Okada, Michio*; Teraoka, Yuden; Kasai, Toshio*

Denki Gakkai Rombunshi, C, 130(10), p.1723 - 1729, 2010/10

https://doi.org/10.1541/ieejeiss.130.1723

The oxidation processes on a TiAl surface induced by a hyperthermal O molecular beam (HOMB) with a translational energy of 2.2 eV was studied by X-ray photoemission spectroscopy in conjunction with synchrotron radiation. At a surface temperature of 300 K, the simultaneous growth of Al and Ti oxides accompanied with the segregation of AlO near the surface was observed. The efficiency of oxidation for the HOMB incidence was smaller than that for O backfilling (25 meV). Furthermore, the chemical compositions of oxide species (AlO, TiO, TiO) on the TiAl surface were independent of the translational energy of incident O molecule. The present results suggest that the oxidation on TiAl surface proceeds via precursor molecular states.

Study of oxidation processes on TiAl by using X-ray photoemission spectroscopy in conjunction with synchrotron radiation

Hashinokuchi, Michihiro*; Sumimoto, Yuichi; Tode, Mayumi; Harries, J.; Teraoka, Yuden; Okada, Michio*; Kasai, Toshio*

no journal, , 

The oxidation processes on TiAl are complex and the composition of the oxide layer depends on various oxidation parameters like sample temperature and oxygen pressure. Therefore, the aim of this work was to examine the initial stages of oxidation of TiAl under different oxidation temperatures and the different kinetic energy of incident oxygen by using X-ray photoemission spectroscopy in conjunction with synchrotron radiation. All experiments were performed with a surface reaction analysis apparatus (SUREAC2000) constructed in BL23SU at SPring-8. The TiAl sample was cleaned by repeatedly argon ion sputtering and annealing. The Oxygen molecules were dosed on the TiAl by hyperthermal oxygen molecular beams or by backfilling oxygen gas.

Hydrogen desorption process from hydrogenated diamond-like carbon film by irradiation of soft X-ray

Kanda, Kazuhiro*; Teraoka, Yuden; Tode, Mayumi; Matsui, Shinji*

no journal, , 

In order to investigate soft X-ray irradiation effects for a diamond-like carbon (DLC) film, thermal desorption spectra (TDS) were observed for a hydrogenated DLC film and a soft X-ray irradiated (300 mAh) hydrogenated DLC film. The temperature elevation rate was 87.5 K/min and the temperature range was from 373 K to 1073 K. In the case of TDS for hydrogen molecules, a large peak was observed around 470 K in the hydrogenated DLC film. The peak, however, was not observed in the non-irradiated hydrogenated DLC film. The elastic recoil analysis showed a large decrease of hydrogen in the X-ray irradiated (300 mAh) sample. We concluded on the basis of these observations that hydrogen molecules desorb by soft X-ray irradiation of 300 mAh.

Effect of surface metal oxide on the desorption of hydrogenation from hydrogenated diamond-like carbon films

Tagawa, Masahito*; Yokota, Kumiko*; Furuyama, Yuichi*; Tode, Mayumi; Yoshigoe, Akitaka; Teraoka, Yuden

no journal, , 

In order to make clear an effect of surface oxide layers for hydrogen desorption processes of hydrogen storage materials, ultra-thin metal oxide layers were formed on diamond-like-carbon (DLC) surfaces containing hydrogen and metals by irradiation of atomic oxygen beams. The thickness of SiO layer formed by the atomic oxygen beam irradiation was estimated to be about 4.5-6.5 nm on the basis of Si/Si photoemission peak area ratio. This value is larger than the diffusion depth of oxygen atoms in an Si crystal at a room temperature. Thermal desorption gas analyses revealed that a hydrogen desorption temperature did not change by the atomic oxygen beam irradiation. However, a hydrogen desorption temperature decreased in the atomic oxygen beam irradiation to a DLC containing Ti. The variation of hydrogen desorption temperature depends on a kind of metal oxide layer.

In situ XPS depth-profiling of hydrogen storage material VCrTi during thermal annealing

Harries, J.; Teraoka, Yuden; Yoshigoe, Akitaka; Tode, Mayumi

no journal, , 

VCrTi is a candidate material for hydrogen storage, and as such information about its surface layer composition is essential. We have used angle-resolved photoelectron spectroscopy to obtain information on the depth distribution of the elements within the alloy, and their chemical states. Also, the changes in this composition are investigated as the temperature of the sample is raised in 100 degree increments up to 800 degrees Centigrade.

Thermal degradation analysis of Vanadium surface oxide layer using high-resolution soft X-ray synchrotron radiation photoelectron spectroscopy

Tode, Mayumi; Harries, J.; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

In order to study the relationships between the thermal desorption of hydrogen and the surface properties, we have used high-resolution synchrotron radiation X-ray photoelectron spectroscopy to study the thermal degeneration processes of the surface layers. All experiments have been conducted at the surface chemistry experimental station (SUREAC2000) at BL23SU, SPring-8. After the surface of V had been cleaned, the deuterium ion was implanted. An artificial oxide layer was formed with a supersonic oxygen molecular beam. V-2p and O1s peaks were observed by SR-XPS. An artificial oxide layer is degeneration between 300 K and 373 K. The desorption of deuterium ion was observed at about 473 K.

Relationships between surface thermal degradation and D thermal desorption of hydrogen storage alloys VCrTi and TiFe

Tode, Mayumi; Harries, J.; Teraoka, Yuden; Yoshigoe, Akitaka

no journal, , 

In order to study the relationships between the thermal desorption of hydrogen and the surface layer, we have used high-resolution synchrotron radiation X-ray photoelectron spectroscopy to study the thermal degeneration processes of the surface layers. The experiments were performed at the JAEA soft X-ray beamline BL23SU at SPring-8, using the "SUREAC2000" surface reaction analysis apparatus. XPS spectra were recorded for room temperature TiFe and V25Cr40Ti35 following flash heating to 373-1073 K. In the un-deuterium implanted TiFe, the photoelectron spectra have changed when heating it at the temperature of 573 K. In the deuterium implanted TiFe, the photoelectron spectra have changed when heating it at the temperature of 473 K. When the deuterium ion was injected, the thermal degeneration temperature of a natural oxide layer was observed to shift to the low temperature side by 150 C.