Modified Bridgman anvils for high pressure synthesis and neutron scattering

ABSTRACT

A simple modified Bridgman design for large volume pressure anvils usable in the Paris-Edinburgh (PE) press has been demonstrated at Oak Ridge National Laboratory Spallation Neutron Source. The design shows advantages over the toroidal anvils typically used in the PE press, mainly rapid compression/decompression rates, complete absence of blow-outs upon drastic phase transitions, simplified cooling, high reliability, and relative low loads (∼40 tons) corresponding to relatively high pressures (∼20 GPa). It also shows advantages over existing large-volume diamond cells as sample volumes of ∼2–3 mm³ can be easily and rapidly synthesized. The anvils thus allow sample sizes sufficient for in situ neutron diffraction as well as rapid synthesis of adequate amounts of new materials for ex situ analysis via total neutron scattering and neutron spectroscopy.

KEYWORDS:

• High pressure neutron scattering
• high pressure material synthesis
• pure amorphous silicon and germanium

Acknowledgments

The authors gratefully acknowledge highly helpful discussion with Malcolm Guthrie (ESS, Sweden) throughout this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 Note that for this run, no pre-compressed gasket with a remaining rim was used but instead a gasket with a 2.5-mm hole, i.e. the same size as the dimple. This resulted in such extrusion of the gasket material that the gasket material cracked. Therefore, the approach with a stabilizing rim was adopted, thereafter.

Additional information

Funding

BH acknowledges funding through a Weinberg Fellowship sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy. RB was partially supported by EFree, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0001057. Research was conducted at three beamlines of ORNL's Spallation Neutron Source, SNAP, NOMAD and VISION, all supported through DOE-BES's Scientific User Facilities division.