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

The pressure stability of the first hydration shell of Y 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 angstrom at ambient conditions, independent on the concentration. The yttrium hydration shell has a low compressibility in the order of angstrom kbar emphasizing its pressure stability in the kbar range. At the studied conditions, no indication for chloride complexation was observed.