Excitation and emission spectra of Pb(2+) ions in Ca(10-x)Pb(x)(PO(4))(6)Cl(2) (0≤x≤10) compounds are investigated for various activator concentrations at different temperatures. A calcium-lead chlorapatite system shows a common apatitic structure and occurs as a continuous solid solution. An attempt to identify the pure electronic transitions between the ground and the excited levels of Pb(2+) is made. As a consequence of the two different sites in the apatite, two emission bands due to the [Formula: see text] (at room temperature) and [Formula: see text] (at low temperature) transitions of the Pb(2+) ions are observed. Decay times of Pb(2+) emission have been measured. Experimental data point out thermalization between (3)P(1) and (3)P(0) levels, for example, at very low temperature, the forbidden transition [Formula: see text] is the most intense. The overlap between the emission band of one site and the excitation band of the other site corresponds to an energy transfer phenomenon. Correlations between the luminescence results and the structural data are discussed.

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Abstract.A continuous solid solution of Pb 8 Na 2-x Ag x (PO 4 ) 6 (0≤ x ≤2) crystallizing in the anionicdeficient apatite structure was obtained by solid-state reaction. The samples were characterized by using X-ray diffraction, infrared absorption spectroscopy, Raman scattering spectroscopy, 31 P MAS-NMR and chemical analysis. The electrical conductivity versus x measured in a wide range of temperature increases with silver content. For each composition, conductivity values obey the Arrhenius law. Correlations between electrical and structural properties are established.