Water hydration at high pressure in Fe3+, Ni2+, and Cu2+ solutions probed by EXAFS
Year: 2026
Authors: Di Cicco A., Hara N., Felici R., Tchoudinov G., Trapananti A., Yoshikawa K., Hatada K., Fanetti S., Santoro M., Irifune T., Busato M., D’Angelo P., Rosa AD., Mijit E.
Autors Affiliation: Univ Camerino, Sch Sci & Technol, Phys Div, I-62032 Camerino, Italy; Univ Toyama, Dept Phys, 3190 Gofuku, Toyama 9308555, Japan; CNR, Ist Chim Composti Organometall, ICCOM, I-50019 Sesto Fiorentino, Italy; CNR, INO, I-50019 Sesto Fiorentino, Italy; Ehime Univ, Geodynam Res Ctr, Matsuyama 7908577, Japan; Sapienza Univ Roma, Dipartimento Chim, Ple Aldo Moro 5, I-00185 Rome, Italy; ESRF, European Synchrotron, 71 Ave Martyrs,CS40220, F-38043 Grenoble 9, France; Lab Non Linear Spect LENS, I-50019 Sesto Fiorentino, Italy; Sorbonne Univ, Inst Mineral Phys Mat & Cosmochimie, MNHN, IMPMC,CNRS, F-75005 Paris, France.
Abstract: We report the results of an EXAFS (extended x-ray absorption fine structure) study of Fe3+, Ni2+, and Cu2+ aqueous solutions under high pressures. EXAFS experiments were performed using synchrotron radiation at room temperature and up to pressures of about 1.2 GPa using a diamond anvil cell. Data analysis has been performed using advanced multiple-scattering simulations, and information about the evolution of the first hydration shell around the metal ions has been obtained. It is shown that Fe3+ and Ni2+ solutions retain a local octahedral structure up to the highest pressure, while Cu2+ solutions show a predominant distorted pyramidal fivefold structure with two oxygen distances. The first-neighbor metal-oxygen distances show a different behavior with pressure in the three solutions, being gradually shortened for Ni(2+ )solutions or elongated in Fe3+ solutions (by similar to-0.01 and similar to 0.02 & Aring; respectively), while in Cu(2+ )solutions, the difference between average equatorial and axial Cu-O distances is gradually reduced. The present results show that pressure does not act as a simple isotropic perturbation on ionic hydration, which is found to be dependent on the bonding mechanisms and ligand-field anisotropy of transition-metal ions.
Journal/Review: JOURNAL OF CHEMICAL PHYSICS
Volume: 164 (8) Pages from: 84501-1 to: 84501-12
More Information: We acknowledge the E.S.R.F. for beamtime allocation and support (Proposal No. HC-5984) and the financial support from the European Union NextGenerationEU (PRIN N. 2022NRBLPT, E-ICES) through the Ministero dell’Universita e della Ricerca (MUR). N. Hara acknowledges the post-doc grant financed through the E-ICES project. K.Y. acknowledges JST SPRING for supporting this work under Grant No. JPMJSP2145. We also thank L. Bove for a critical reading of the text before publication and useful suggestions concerning this work.KeyWords: X-ray-absorption; Molecular-dynamics Simulations; Body Distribution-functions; Aqueous-solutions; Condensed Matter; High-temperature; High-density; Metal-ions; Exchange; CoordinationDOI: 10.1063/5.0316717
