Pressure stability of the first hydration shell of yttrium in aqueous YCl₃ solution

ABSTRACT

The pressure stability of the first hydration shell of Y${}^{3+}$ ions in aqueous solution has been investigated by means of extended x-ray absorption fine-structure spectroscopy at the yttrium K-edge for hydrostatic pressures up to 4.5 kbar and concentrations between 1 M and 2.5 M. We find approximately 8.4 water molecules surrounding the yttrium cation at a mean distance of 2.370 Å at ambient conditions, independent on the concentration. The yttrium hydration shell has a low compressibility in the order of $(-3.8\pm 0.7)\times {10}^{-4}$ Å kbar${}^{-1}$ emphasizing its pressure stability in the kbar range. At the studied conditions, no indication for chloride complexation was observed.

KEYWORDS:

• X-ray absorption spectroscopy
• hydration
• structure of aqueous solution
• YCl${}_3$

Acknowledgments

We acknowledge DELTA for providing synchrotron radiation beamtime at beamline BL8 and thank Patrick Degen, Florian Wirkert, Paul Salmen, Karin Esch and Holger Göhring (all of TU Dortmund, Germany) for help with preparation and conduction of the experiments. We are grateful to Max Wilke for invaluable discussions and thank the joint usage/research center PRIUS at the GRC (Ehime University, Japan) for providing nano-polycrystalline diamond discs.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support by the BMBF via project 05K16PE1 (ME, CS, MT) and by the Cluster of Excellence RESOLV (EXC 1069) under Germany's Excellence Strategy – EXC-2033 – Projektnummer 390677874 (MT, KJ) and the FOR 1979 (JN, GS) both funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) is gratefully acknowledged.