XAFS study on the trace amounts of ytterbium ions incorporated in calcium carbonate crystal

H. Tsuno, H. Kagi, Y. Takahashi, T. Akagi, M. Nomura

Research output: Contribution to journalConference article

4 Citations (Scopus)

Abstract

We measured XAFS spectra of trace amount of ytterbium (Yb) incorporated in calcite, a stable phase of calcium carbonate. Calcium carbonate was precipitated from a mixed solution of CaCl2 aq and NaHCO3 aq with a given amount of YbCl3. Concentrations of Yb were 5 μmol kg -1 in the starting solutions and Yb/Ca molar ratio in the precipitated calcium carbonate was 1.2 × 10-3. Ytterbium L III-edge XAFS spectra were collected in the fluorescence mode at the beamline BL-12C of the KEK-PF. Analysis of the XAFS results indicated, (1) Approximately 15% Yb ion existed as divalent ions in the calcite. (2) Yb 3+, major Yb species in the calcite, is located at the Ca 2+ site in the calcite. The local structure around Yb3+ is significantly different from that of Ca2+. The coordination number of Ca2+ in the crystal structure of calcite is 6 and Ca-O distance is 2.36?Å. In contrast, the nearest Yb-O coordination for Yb-doped calcite is split into two shells, the nearest 4 oxygen atoms and the second nearest 2 oxygen atoms, and their Yb-O distances are 2.24?Å and 2.77?Å, respectively. It was shown that localized structural relaxation occurred around Yb3+ which has smaller ionic radius than Ca2+.

Original languageEnglish
Pages (from-to)897-900
Number of pages4
JournalPhysica Scripta T
VolumeT115
DOIs
Publication statusPublished - 2005
Event12th X-ray Absorption Fine Structure International Conference, XAFS12 - Malmo, Sweden
Duration: Jun 23 2003Jun 27 2003

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Mathematical Physics
  • Condensed Matter Physics

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