Site-selective spectroscopy and determination of energy levels in Eu3+-doped strontium fluorophosphate

Abstract

Absorbance and site-selective fluorescence studies of Eu3+:Sr5(PO4)3F (Eu:SFAP) provide a nearly complete characterization of the Eu3+ energy levels. These results are compared with calculated energies generated by lattice-sum analysis. Eu3+ is found to occupy one site predominantly, but numerous minority sites are also evident; polarization studies of absorption and fluorescence lines provide evidence for the principle site having Cs symmetry. Vibronic transitions occur in spectra as well. Interpretation of the lattice location and charge compensation mechanism for the principal site is discussed in the context of obstacles arising from spectral interpretation, high crystal fields in SFAP, low site symmetry, low J-numbers in Eu3+ energy manifolds, and lattice covalency. Eu2+ emission upon ultraviolet excitation is also demonstrated; valleys in the emission profile are attributed to intracrystal absorption by Eu3+.

Eu3+ luminescence—a structural probe in BiCa4(PO4)3O, an apatite related phosphate

“…Eu 3+ has a simple electronic energy level scheme among the rare earth ions and the transitions are hypersensitive, i.e., they depend strongly on the chemical surroundings [2]. Because of these hypersensitive transitions, Eu 3+ has been used as a local structure probe in determining the microscopic symmetries of different sites available in various host lattices, such as apatites [3][4][5][6][7][8][9][10] and eulytines [11]. Studies on the Eu 3+ luminescence in Sr 10 (PO 4 ) 6 F 2 synthesized by coprecipitation method show that Eu 3+ has OH À or O 2À as neighboring ions and Eu 3+ is present in a site with C s symmetry that gives rise to the 5 D 0 -7 F 0 emission line at 576 nm [12].…”

Single crystal growth of Pb5(PxAs1−xO4)3Cl solid solution with apatite type structure

“…This fact has launched many studies for exploring the possibility of synthesizing solid solutions based on an apatite structure. Aside from their biological importance [2][3][4][5], apatite-type compounds have been studied extensively for potential use as fluorescent lamp phosphors [6,7], oxide ion conductors [8,9], and laser host materials [10,11]. The extensive solid solution is known between many end members in the group, particularly between pyromorphite Pb 5 (PO 4 ) 3 Cl and mimetite Pb 5 (AsO 4 ) 3 Cl [1,12].…”

Dependence of Eu3+ luminescence dynamics on the structure of the combustion synthesized Sr5(PO4)3F host

“…Spectroscopic properties of trivalent rare-earth (RE) ions such as Pr 3+ , Nd 3+ , Ho 3+ , Er 3+ and Tm 3+ incorporated crystals of strontium fluorapatite (SFAP) or Sr 5 (PO 4 ) 3 F have been reported [1][2][3]. These studies were motivated by the potential use of SFAP either as a laser host material, or as a saturable switch absorber [4].…”