Aqueous speciation of yttrium at temperatures from 25 to 340 degrees C at P-sat: an in situ EXAFS study

KV Ragnarsdottir*, EH Oelkers, DM Sherman, CR Collins

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

The solvation environment of aqueous yttrium in chloride bearing solutions was characterised by EXAFS spectroscopy at temperatures from 25 to 340 degrees C. Four solution compositions were considered containing 0.1 M YCl3, 0.1 M YCl3 + 0.23 M HCl + 1.0 M NaCl, 0.1 M YCl3 + 0.23 M HCl + 2.0 M NaCl, and 0.05 M Y(NO3)(3), respectively. Yttrium was found to be surrounded by an inner coordination shell of H2O, the coordination number decreasing from 9-10 to similar to 8 with increasing temperature from 25 to 340 degrees C. The Y-O interatomic distance is constant 2.37 +/- 0.02 Angstrom at temperatures up to 340 degrees C. Yttrium chloride inner sphere complexing is negligible up to 340 degrees C for all solutions, including that containing 2.5 M chloride. This observation implies that chloride inner sphere complexes play an insignificant role in the solubility and transport of yttrium, and by analogy the heavy rare-earth elements in sub critical crustal fluids. Data analysis of EXAFS spectra of the 0.1 M YCl3 solution at temperatures in excess of 250 degrees C indicate the presence of yttrium atoms located at similar to 3.6 Angstrom and similar to 4.9 Angstrom from the central yttrium atom. This latter observation is consistent with yttrium polyatomic species formation, or polymerisation. (C) 1998 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)29-39
Number of pages11
JournalChemical Geology
Volume151
Issue number1-4
Publication statusPublished - 1 Oct 1998
EventEuropean Research Conference on the Geochemistry of Crustal Fluids - SEEFELD, Austria
Duration: 6 Dec 199611 Dec 1996

Keywords

  • yttrium
  • aqueous speciation
  • EXAFS
  • water structure
  • REE
  • polyatomic species
  • RARE-EARTH ELEMENTS
  • X-RAY-ABSORPTION
  • CURVED-WAVE THEORY
  • HYDROTHERMAL FLUIDS
  • THERMODYNAMIC PROPERTIES
  • SOLUBILITY PRODUCTS
  • INORGANIC COMPLEXES
  • NEUTRON-SCATTERING
  • CHLORIDE SOLUTIONS
  • PERCHLORATE-MEDIA

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