Effect of implanted helium on thermal diffusivities of SiC/SiC composites

Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro; Shimura, Kenichiro

Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.469 - 472, 2006/01

https://doi.org/10.1016/j.nimb.2005.08.126

SiC/SiC composites are one of the candidate materials for first wall in a fusion reactor because of their high strength at high temperature and low residual radioactivity after irradiation. In the fusion reactor, these materials are required to have high thermal diffusivity for heat exchange and reducing the thermal shock. Under fusion conditions, helium (He) and hydrogen (H) are produced in SiC. In this study, the effect of He ions implantation on the thermal diffusivities of SiC and SiC/SiC composite were investigated. In the results, the thermal diffusivities of SiC and SiC/SiC composites decreased after He ions implantation. However, the thermal diffusivities of SiC and SiC/SiC composites hardly reduced in the operation temperature of fusion reactor. The thermal diffusivities of He implanted specimens were partly recovered by annealing. The defect concentration induced by He implantation, X, in SiC/SiC composites was estimated. The X rapidly decreased around 500 C. The reason is that the He release from SiC starts at 500 C.

Chemical state of tritium in Sr-Ce oxide ceramics and its removal characteristics (Cooperative research)

Nakamura, Hirofumi; Nishi, Masataka; Morita, Kenji*

JAERI-Research 2003-016, 32 Pages, 2003/08

JAERI-Research-2003-016.pdf:5.5MB

As a part of the detritiation study from the fusion reactor materials, chemical state of tritium injected into Sr-Ce base oxide ceramic proton conductor, which is a candidate for a tritium recovery system, was investigated with thermal desorption method. The results indicated that the oxide has to be heated up over 1300K to remove tritium due to the OT bond formation in the oxide. On the other hand, tritium removal behavior from the oxide were also investigated by exposing to humid air, and the mechanism of tritium removal from the oxide was identified by the dependency of tritium removal amount and chemical state on the humidity. The results revealed that tritium removal rate by the air exposure was low, and that almost tritium was removed as the vapor form, which was attributed to the isotope exchange reaction between the OT bond on the surface and the protium in vapor. It was also found that small amount of tritium was removed as elemental form under the humid air exposure, which could be attributed to the solute tritium in the oxide and oxygen absorption to the oxygen deficit in the oxide. As a result, the difference of the detritiation mechanism exposed to the humid air on the chemical state of tritium in the oxide was clarified, and it could be a useful basic data for the optimization of detritiation method.

Formation of TiOF compounds in fluorine-implanted TiO

Yamaki, Tetsuya; Sumita, Taishi; Yamamoto, Shunya

Journal of Materials Science Letters, 21(1), p.33 - 35, 2001/01

https://doi.org/10.1023/A:1014282225859

We showed the effects of 200 keV F implantation in TiO rutile single crystals followed by the thermal annealing. The isochronal annealing at 573 and 873 K for 5 h for each step led to the formation of an F-doped TiO phase, along with the recovery of the radiation damage and the simultaneous impurity diffusion. This phase was identified to be a TiOF compound with x = 0.0039 in the outmost region as determined by X-ray photoelectron spectroscopy (probably the first few atomic layers). The fluorination of TiO leads to interesting characteristics and opens avenues towards photoelectronic films with various applications. In addition, our method enabled dopants to be introduced in a controlled manner at specific locations to realize impurity concentration gradients in TiO.

High energy Ni ion implantation and thermal annealing for -SiC single crystal

*; Kawatsura, Kiyoshi*; Arai, Shigeyoshi*; *; *; *; *; Takeshita, Hidefumi; Yamamoto, Shunya; Aoki, Yasushi; et al.

Nuclear Instruments and Methods in Physics Research B, 91, p.529 - 533, 1994/00

https://doi.org/10.1016/0168-583X(94)96280-4

no abstracts in English

Chemical states and thermal stability of hydrogen-implanted Ti and V studied by X-ray photoelectron spectroscopy

;

Journal of Nuclear Materials, 132, p.173 - 180, 1985/00

https://doi.org/10.1016/0022-3115(85)90412-X

no abstracts in English

Ion implantation and thermal annealing of -AlO single crystals

; C.W.White*; J.M.Williams*; C.J.McHargue*; O.W.Holland*; M.M.Abraham*; B.R.Appleton*

Journal of Applied Physics, 54(2), p.683 - 698, 1983/00

https://doi.org/10.1063/1.332076

no abstracts in English