An opposed-anvil-type apparatus with an optical window and a wide-angle aperture for neutron diffraction

Abstract

We designed new anvil assemblies for acquiring high-quality neutron diffraction data and ruby fluorescence spectra inside a sample chamber. The conical aperture of Ni-binded WC anvils was expanded by a factor of two. A hybrid gasket made of TiZr- and Al-alloy was developed to prevent outward extrusion. A small and optically transparent window of moissanite was introduced to allow for the determination of pressure and hydrostaticity by measurement of ruby fluorescence spectra. High pressure-generation tests that make use of Bi electrical conductivity and ruby pressure markers revealed that pressure could be determined over 10 GPa. In situ synchrotron X-ray diffraction experiments were also carried out using NaCl as the pressure calibrants. The maximum pressure achieved was approximately 13 GPa. The neutron diffraction intensity from the newly generated anvil assemblies was 2.5–3.0 times greater than that using the standard toroidal anvil assemblies used previously.

Keywords:

• Paris–Edinburgh cell
• neutron diffraction
• ruby fluorescence
• optical window
• hydrogen bond

Acknowledgements

The authors are grateful to Drs A. Sano-Furukawa, H. Arima, T. Hattori, and J. Abe (Japan Atomic Energy Agency) for their help with the neutron diffraction experiments at J-PARC. We are grateful to Professor T. Kamiyama (KEK) for providing access to a P–E press. We also thank Dr K. Kitagawa and Mr K. Wada for the helpful advice regarding moissanite anvils and WC anvils. This work was supported by Grant-in-Aid for JSPS Fellows for Young Scientists (DC2), Creative Scientific Research (19GS0205), Innovative areas (No. 2002), and the Global COE Programs for Chemistry Innovation and Deep Earth Mineralogy from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. In situ X-ray experiments were performed at the PF, KEK (2008G066).