| Autor: |
Deyin Wang, Nobuhiro Kodama, Lei Zhao, Yuhua wang |
| Předmět: |
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| Zdroj: |
Journal of The Electrochemical Society; 2010, Vol. 157 Issue 6, pJ233-J237, 5p |
| Abstrakt: |
Photoluminescence properties of Eu3+- or Th3+-doped Na2GdF2PO4 under UV and vacuum ultraviolet (VUV) excitations are investigated. A broad band with the maximum at 172 nm observed in the VUV excitation spectra of Na2GdF2PO4:Re (Re = Eu3+ and Tb3+) is assigned to the host absorption. The excitation intensity ratio of O2- → Eu3+ charge transfer to that of the intraconfigurational 4f-4f transitions of Gd3+ and Eu3+ is rather low in Na2GdF2PO4:Eu3+ showing that energy transfers efficiently from Gd3+ to Eu3+ and Eu3+ to Eu3+ and the covalency of O2-Eu3+ is increased due to the existence of F. The energy-transfer process in Na2GdF2PO4:Tb3+ upon host excitation and Tb3+ 4f75d-4f8 excitation is explained by a quantum cutting process. The quantum cutting involves a cross relaxation process between two neighboring Tb3+ and direct energy transfer between Tb3+ and Tb3+ or Tb3+ and Gd3+, depending on the excitation wavelength. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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