High-pressure neutron diffraction apparatus for investigating the structure of liquids under hydrothermal conditions

ABSTRACT

A high-pressure setup is described for making neutron diffraction experiments on liquids under hydrothermal conditions. Designs are given for a modified Bridgman unsupported area seal, a fluid separator that keeps apart the liquid sample and pressurising fluid, and a pressure-cell made from the null-scattering alloy Ti${}_{0.676}$Zr${}_{0.324}$. Special attention is paid to the choice of construction materials used to avoid corrosion by the liquid sample under load at elevated temperatures. The apparatus is used to investigate the structure of heavy water at pressures up to 2 kbar and temperatures up to 250${}^{\circ }$C.

KEYWORDS:

• Modified Bridgman unsupported area seal
• high-pressure separator
• Ti–Zr high-pressure cell
• neutron diffraction
• structure of water

Acknowledgments

We are grateful to Alain Bertoni and Claude Payre for their help with the D4c experiment, to Ruth Rowlands, Stefan Klotz and Marie-Claire Bellissent-Funel for their help with earlier experimental work at the Laboratoire Léon Brillouin, and to George Neilson and Adrain Barnes for providing the Ti–Zr cell that was used in these test experiments.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Burkhard Annighöfer http://orcid.org/0000-0002-7362-0652

Annalisa Polidori http://orcid.org/0000-0001-9881-0543

Anita Zeidler http://orcid.org/0000-0001-6501-8525

Henry E. Fischer http://orcid.org/0000-0002-1204-0750

Philip S. Salmon http://orcid.org/0000-0001-8671-1011

Additional information

Funding

The Bath group received support from the UK Engineering and Physical Sciences Research Council (EPSRC) via Grant No. EP/J009741/1. AZ is supported by a Royal Society–EPSRC Dorothy Hodgkin Research Fellowship, and AP was supported by a PhD studentship funded by the Institut Laue Langevin (ILL) and University of Bath.