The spectroscopic properties of the Eu3+ and Pr3+ ions in the weberite, Ca2La3Sb3O14 are examined in this paper. The Eu3+ is used as a structural probe ion to elucidate the local site symmetry of the La3+ ion in Ca2La3Sb3O14. The interpretation of the Eu3+ emission spectrum is not consistent with the C-2h and S-2 (C-i) point symmetry that are prescribed for the La3+ sites by the I2/m11 space group of Ca2La3Sb3O14. The emission spectrum of Ca2La3Sb3O14:Pr3+ is dominated by emission transitions emanating from the D-1(2) state. The low energy of the Pr(3+)4f(2) -> 4f(1)5d(1) interconfiguration excitation transition in Ca2La3Sb3O14 (3.83 eV or 32 258 cm(-1)) is attributed to the high covalence which is induced by short Pr3+-O2- bond distances within the coordination polyhedral units in the lattice. The high covalence of chemical bonding appears to be the hallmark of the weberite structure. A study that compares the optical properties of Eu3+ and Pr3+ in the weberites, Ca2La3Sb3O14 and NaGdSb2O7 is presented. (C) 2014 Published by Elsevier B.V.
Luminescence of Eu3+ and Pr3+ in the weberite, Ca2La3Sb3O14
Trevisani, Mattia;BETTINELLI, Marco Giovanni
2014-01-01
Abstract
The spectroscopic properties of the Eu3+ and Pr3+ ions in the weberite, Ca2La3Sb3O14 are examined in this paper. The Eu3+ is used as a structural probe ion to elucidate the local site symmetry of the La3+ ion in Ca2La3Sb3O14. The interpretation of the Eu3+ emission spectrum is not consistent with the C-2h and S-2 (C-i) point symmetry that are prescribed for the La3+ sites by the I2/m11 space group of Ca2La3Sb3O14. The emission spectrum of Ca2La3Sb3O14:Pr3+ is dominated by emission transitions emanating from the D-1(2) state. The low energy of the Pr(3+)4f(2) -> 4f(1)5d(1) interconfiguration excitation transition in Ca2La3Sb3O14 (3.83 eV or 32 258 cm(-1)) is attributed to the high covalence which is induced by short Pr3+-O2- bond distances within the coordination polyhedral units in the lattice. The high covalence of chemical bonding appears to be the hallmark of the weberite structure. A study that compares the optical properties of Eu3+ and Pr3+ in the weberites, Ca2La3Sb3O14 and NaGdSb2O7 is presented. (C) 2014 Published by Elsevier B.V.
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