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Hanada, Masaya
Purazuma, Kaku Yugo Gakkai-Shi, 78(6), p.541 - 547, 2002/06
The beam technology developed for neutral beam injection in fusion application has been applied to industry. Presently, positive ion beams are widely applied to process the semiconductor. For example, an intense argon ion beam is used for milling substrates of the semiconductor, and a large liquid crystal is also manufactured by implanting P+ or B+ ions on glass plates. Recently, the intense negative ion beam has also been developed and is being applied to new field in semiconductor industry. Japan Atomic Energy Research Institute (JAERI) is developing new technology for slicing the thin single-crystal semiconductor plates of several tens of micrometers in thickness from the ingot without waste by implanting the MeV-class H
ion beam developed for ITER. This process is realized only by using the high-energy negative ion beam since the positive ion implantation requires the mass separation that practically limits the ion beam energy, namely, penetration depth of the ions. By implanting 725 keV H ions directly onto the Si ingot, the single-crystal Si plates of 10 mm in thickness have successfully been sliced. It is expected that this technology opens mass productions of high efficiency solar cells and micro-machines.
Serizawa, Hiroyuki
no journal, ,
My investigation on cavities in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO
matrix. The SEM image that attracted my attention was a cavity observed in the fracture surface of a single crystal of UO that was heat-treated in helium at 90 MPa, followed by annealing at 1573 K for 1 h. It was clear that the cavity was a negative crystal that was formed by the precipitation of helium during heat treatment after Hot Isostatic Pressing (HIP) injection. In a series of experiments, I noticed that the shape of the negative crystal changes depending on the heat-treatment history. A truncated octahedron-type, an octa-triacontahedron-type, and a pentacontahedron-type negative crystal were observed. Our study implies that the shape of the negative crystal should change depending on the helium inner pressure enclosed in the negative crystal.
Serizawa, Hiroyuki
no journal, ,
My investigation on cavities in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO matrix. In a series of experiments, I noticed that the shape of the negative crystal changes depending on the heat-treatment history. In general, it is difficult to control arbitrarily the shapes of these polyhedral negative crystals embedded in a solid medium; however, the shape can easily be controlled using the helium injection method. Our research team named the shape controlled negative crystal as image crystal.
Serizawa, Hiroyuki
no journal, ,
My investigation on cavities in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO matrix. The SEM image that attracted my attention was a cavity observed in the fracture surface of a single-crystal of UO that was heat-treated in helium at 90 MPa, followed by annealing at high temperature for 1 h. The cavity was the so-called negative crystal which is sometimes seen in a broken mineral casually. The negative crystal was formed by the precipitation of helium during heat treatment after Hot Isostatic Pressing (HIP) injection. In a series of experiments, I noticed that the shape of the negative crystal changes depending on the heat-treatment history. We also confirmed that nanosized image crystals can be formed in CeO matrix.
Serizawa, Hiroyuki
no journal, ,
My investigation on cavities in ceramics was triggered by the unexpected discovery of a polyhedral cavity in a UO matrix. we discovered that three types of image crystals and determined the shape by reported value of the attachment energy and the step free energy mode. We conducted further research on the formation of image crystals in CeO.
Serizawa, Hiroyuki; Kaji, Yoshiyuki; Yamamoto, Shunya*; Yasunaga, Kazushi*; Oishi, Yuji*; Yamanaka, Shinsuke*
no journal, ,
Pieces of CeO(100) thin film were heat treated at 1273 K for 2h. The films were irradiated with 130-keV He
ions from 400-keV ion implanter of TIARA. The ion doped film was heat treated at 1773 K for 2h in air. The sample for STEM analysis was prepared by FIB. It was found that many blisters are formed on the surface of the thin film. The idea of gas-driven blister growth on a metal surface was first proposed by Evans et al.. So, the blisters are considered to be formed by gas babble formed accompanied by precipitation of He just under the surface. Many gas babbles are formed in the thin film. The size of the gas bubble falls within the range 30-100 nm. The shape of the gas bubble is truncated octahedron but clearly different from that of void, which mean, the existence of He in the gas bubble effect on the shape of the gas bubble.
Serizawa, Hiroyuki
no journal, ,
We found that porous uranium dioxide grain was formed by the precipitation of helium injected by HIP. Scanning electron microscopy analysis showed that polyhedral negative crystals were formed in the sample. The shape of the negative crystal changes dramatically with the conditions of helium precipitation. A truncated octahedron-type, an octatriacontahedron-type, and a pentacontahedron-type negative crystal were observed. Our study implies that the shape of the negative crystal should change depending on the helium inner pressure enclosed in the negative crystal. It is difficult to arbitrarily control the shapes of these polyhedral negative crystals embedded in a solid medium. However, the shape of the negative crystal can easily be controlled by the helium injection method. In this article, we call the shape controlled negative crystal an image crystal. Here, we report a relationship between the surface energy and the shape and discuss the transformation mechanism of the image crystal.
Serizawa, Hiroyuki
no journal, ,
The speech is invited one by the organization committee of the International Congress. The presenter is now carrying out the investigation on the formation of Negative crystal in FCC-type oxide. In this congress, The presenter talks about shape controllable negative crystal formed in UO formed by the precipitation of He. The speech also includes the progress of the experimental study on the formation of Negative crystal in CeO. A tentative potential of the ceramics including the negative crystal as a optical material is also discussed.
