# Site-selective emission spectra of Eu$^{3+}$:Ca$_5$(PO$_4$)$_3$F

Abstract : The room temperature site-selective fluorescence and excitation spectra of Eu3+:FAP powder samples as well as the decay times of the observed emission lines associated with the D-5(0) --> F-7(0,1,2) transitions have been measured. In sample I, prepared by the thermally stimulated diffusion of Eu2O3 in the solid state, Eu3+ reside only in the Ca(II) location which has C-s symmetry. Experimental values for the Stark energy levels have been determined for three well-separated sites. Sites A and B exhibit very similar spectral features attributed to the presence of the charge-compensating O2- ion in the F- position in the FAP lattice, whereas for Eu3+ in site C the charge is most probably compensated by vacancies according to 3Ca(2+) --> 2Eu(3+) +Vacancy substitution. In sample II, prepared by precipitation of Eu3+(1%):FAP from solution, Eu3+ substitute for calcium in the Ca(I) position exclusively and three sites with C-3 symmetry have been identified. Substitution of 3Ca(2+)/2Eu(3+) is the most probable charge-compensation mechanism. Heating of sample II stimulates the migration of Eu3+ from the Ca(I) position to the low symmetry Ca(II) site.
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http://hal.in2p3.fr/in2p3-00007805
Contributor : Suzanne Robert Connect in order to contact the contributor
Submitted on : Wednesday, May 31, 2000 - 9:49:39 AM
Last modification on : Wednesday, September 16, 2020 - 4:00:58 PM

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• HAL Id : in2p3-00007805, version 1

### Citation

M. Karbowiak, S. Hubert. Site-selective emission spectra of Eu$^{3+}$:Ca$_5$(PO$_4$)$_3$F. Journal of Alloys and Compounds, Elsevier, 2000, 302, pp.87-93. ⟨in2p3-00007805⟩

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