Crystal structure change of katoite, CaAl(OD), with temperature at high pressure

Kyono, Atsushi*; Kato, Masato*; Sano, Asami; Machida, Shinichi*; Hattori, Takanori

Physics and Chemistry of Minerals, 46(5), p.459 - 469, 2019/05

https://doi.org/10.1007/s00269-018-1016-4

To reveal the decomposition mechanism with temperature under high-pressure, crystal structure of a hydrogrossular, katoite CaAl(OD) has been studied by in-situ neutron diffraction at 8 GPa. Although unusual expansion behavior was discerned at 200-400C, the unit cell was continuously expanded up to 850C. At 900C, katoite was decomposed, indicating that pressure strongly increases dehydration temperature from 300C to 900C. On release of pressure, the katoite reappear together with corundum and portlandite. At 8 GPa, CaO and AlO polyhedra expand with temperature up to 850C by about 8% and 13%, respectively. On the other hand, tetrahedral interstices are isotopically squeezed by about 10%: due to the expansion of above polyhedra. The neighboring D-D distance remains almost unchanged in this temperature range, while the O-D bond distance shrinks drastically just before decomposition. This finding suggests that the shortening of O-D distance caused by the D-D repulsion destabilizes the O-D bond, which induces the thermal decomposition of katoite.

Improvement of high-voltage performance of acceleration tubes by cleaning the walls with a high-pressure water jet

Takeuchi, Suehiro; Nakanoya, Takamitsu; Kabumoto, Hiroshi; Yoshida, Tadashi

Nuclear Instruments and Methods in Physics Research A, 513(3), p.429 - 438, 2003/11

https://doi.org/10.1016/S0168-9002(03)02080-1

At the JAERI Tandem accelerator, an acceleration tube replacing plan is proceeding to increase the acceleration voltage toward 20 MV. Lengthy conditioning is generally necessary for a large tube system. We had an idea to clean the tubes with high-pressure water-jet rinsing before installation. We cleaned tubes and tested them at 1 MV and 3 MV. The both results exhibited that the voltages went beyond the rated voltages and discharge activities were much less than the old records. During the test of new tubes at 3 MV, the conditioning proceeded well and an extremely stable condition was fulfilled within 24 hours. In conclusion, the cleaning was found to be a very promising way to improve high-voltage performance of the tubes in a large tube system.

Pressure-variation of structure factor of liquid Rb

*; G.Kahl*

Japanese Journal of Applied Physics, 38(SUPPL.38-1), p.492 - 495, 1999/00

https://doi.org/10.1143/JJAP.38.L492

no abstracts in English

Core void fraction distribution under high-temperature high-pressure boil-off conditions; Experimental study with two-phase flow test facility(TPTF)

; Kumamaru, Hiroshige; Murata, Hideo; Anoda, Yoshinari; Kukita, Yutaka

JAERI-M 93-200, 56 Pages, 1993/10

JAERI-M-93-200.pdf:1.85MB

no abstracts in English

Post-dryout heat transfer of steam-water two-phase flow in rod bundle under high-pressure and low-flow conditions

Kumamaru, Hiroshige; Kukita, Yutaka

ANS Proc. 1991 National Heat Transfer Conf., Vol. 5, p.22 - 29, 1991/00

no abstracts in English

Slug to annular flow transition during boiloff in a rod bundle under high-pressure conditions

Osakabe, Masahiro; Koizumi, Yasuo; ; ; Tasaka, Kanji

Nucl.Eng.Des., 98, p.69 - 76, 1986/00

https://doi.org/10.1016/0029-5493(86)90121-4

no abstracts in English

Fabrication and Performance Test of NSRR High-Temperatur High-Pressure Loop

; ;

JAERI-M 83-039, 118 Pages, 1983/03

JAERI-M-83-039.pdf:3.07MB

no abstracts in English

High-pressure inelastic experiments using a Paris-Edinburgh press and clamp cell

Hattori, Takanori; Nakamura, Mitsutaka; Iida, Kazuki*; Kawamura, Seiko; Sano, Asami; Machida, Shinichi*

no journal, , 

Since the pressure reduces the distance between atoms in a substance and directly changes the interatomic interaction, it is possible to greatly change the state of the substance with individual structure and physical properties. The response is a good clue to understand the mechanism of physical properties. Although inelastic scattering is effective for investigating the dynamics of a substance, experiments under high pressure have been limited mainly for three reasons: inelastic scattering is weak, high pressure specimens are small, neutron sources are weak. However, if we use spectrometers (BL01, 14) with high S/N ratio at J-PARC MLF, an inelastic scattering experiment under high pressure seems to be possible. Thus, we performed the feasibility test using a Paris Edinburgh press and clamp cell. In this talk, the results will be introduced.

Recent developments and current status of high-pressure neutron diffractometer PLANET in J-PARC

Hattori, Takanori; Sano, Asami; Machida, Shinichi*; Abe, Jun*; Funakoshi, Kenichi*; Arima, Hiroshi*

no journal, , 

The first domestic high-pressure powder neutron diffractometer PLANET celebrated five years since its operation started. Here, we will introduce the current status and subsequent progress. Expansion of measurable PT region: In the experiments using a 6-axis press, in-situ observation at 14 GPa, 1800 K became possible by increasing the anvil strength by shrink fitting and replacing a graphite with a TiC + AlO heater. In experiments using the Paris Edinburgh Press (PE press), by reducing the anvil top to 2.5 mm in diameter, experiments at 30 GPa are possible. Improvement of measurement data quality: when using a PE press, samples are normally pressurized together with liquid pressure medium to avoid peak broadening. However, above 10 GPa, the medium solidifies and the peaks are broadened. To fix this problem, a system capable of heating the sample up to 100C was designed and now we can obtain sharp diffraction peaks up to 20 GPa. New measurement method: In order to obtain macroscale information of samples under high PT condition, we attempted neutron radiograph. By using a compact neutron camera, we can place a camera close to the sample and obtain high resolution images.