Large volume multianvil cell assembly for hydrothermal synthesis and conversions up to 6.5 GPa and 400°C

ABSTRACT

A multianvil cell assembly with octahedral edge length 25 mm has been adapted for high pressure investigations involving water-rich environments up to 6.5 GPa and 400°C. Water-rich samples are confined in Teflon containers with a volume up to 300 mm³. Applicability tests were performed between 250 and 400°C by investigating the transformation of amorphous titania particles close to the rutile–TiO2-II (∼5 GPa) phase boundary, and the transformation of amorphous silica particles close to the quartz–coesite (∼2.5 GPa) and coesite–stishovite (∼7 GPa) phase boundaries. The performed experiments employed 25.4 mm tungsten carbide anvils with a truncation edge length of 15 mm. The sample pressure at loads approaching 820 t was estimated to be around 6.5 GPa. The large volume multianvil cell is expected to have broad and varied application areas, ranging from the simulation of geofluids to hydrothermal synthesis and conversion/crystal growth in aqueous environments at gigapascal pressures.

KEYWORDS:

• Multianvil
• large sample volumes
• hydrothermal conditions
• Teflon capsules
• coesite
• TiO₂- II

Acknowledgements

We acknowledge the assistance of FORCE staff members. The Facility for Open Research in a Compressed Environment (FORCE) at ASU is funded by NSF-EAR under the Mid-scale Research Infrastructure-1 award #2131833. We acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160. We acknowledge Jekabs Grins at Stockholm University for his help in analyzing some of the powder diffraction patterns. We are especially grateful to William Chapin at the ASU CLAS Research Technical Serv., Instrument Design & Fabrication Core for skillfully fabricating the Teflon sample capsules.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was partially supported by the Knut and Alice Wallenberg Foundation (Grant No. KAW 2018.0019) and COMPRES, the Consortium for Materials Properties Research in Earth Sciences under NSF Cooperative Agreement EAR 1606856.