The luminescence spectroscopy of Tb3+ and Eu3+ has been studied in the Ca9Tb(PO4)(7), Ca9Eu(PO4)(7), and Ca(9)Tb(0.9)Eua,(PO4)(7) materials having a whitlockite structure, by using excitation in the near UV, vacuum UV and X-ray regions. The Eu3+ ion in Ca9Eu(PO4)(7) is located mainly in two cationic sites, as evidenced by the fine structure of the D-5(0) -> E-7(0) transition at 5 K. In the case of Ca9Tb0.9Eu0.1(PO4)(7), weak Tb3+ -> Eu3+ energy transfer is observed upon excitation in the UV bands of Tb3+. The low efficiency of the transfer appears to be due to slow energy migration in the D-5(4) subset of the Tb3+ ions. The overall behavior is strongly affected by the multisite and disordered nature of the Tb-based whitlockite host.
Optical Spectroscopy of Ca9Tb1–xEux(PO4)7 (x = 0, 0.1, 1): Weak Donor Energy Migration in the Whitlockite Structure
Piccinelli, Fabio;Bettinelli, Marco
2017-01-01
Abstract
The luminescence spectroscopy of Tb3+ and Eu3+ has been studied in the Ca9Tb(PO4)(7), Ca9Eu(PO4)(7), and Ca(9)Tb(0.9)Eua,(PO4)(7) materials having a whitlockite structure, by using excitation in the near UV, vacuum UV and X-ray regions. The Eu3+ ion in Ca9Eu(PO4)(7) is located mainly in two cationic sites, as evidenced by the fine structure of the D-5(0) -> E-7(0) transition at 5 K. In the case of Ca9Tb0.9Eu0.1(PO4)(7), weak Tb3+ -> Eu3+ energy transfer is observed upon excitation in the UV bands of Tb3+. The low efficiency of the transfer appears to be due to slow energy migration in the D-5(4) subset of the Tb3+ ions. The overall behavior is strongly affected by the multisite and disordered nature of the Tb-based whitlockite host.
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