K. Bakhous et al., Structural approach and luminescence properties of La1/6Pb1/3Zr2(PO4)(17/6)(SiO4)(1/6): Eu3+, J SOL ST CH, 146(2), 1999, pp. 499-505
Rare earth phosphosilicates (Li1-xEux)(1/6)Pb1/3Zr2(PO4)(17/6) (SiO4)(1/6)
0 less than or equal to x less than or equal to 1 have been synthesized via
a sol-gel route, The powder X-ray diffraction has been analyzed with the N
asicon-type structure. The Rietveld analysis of the structure performed in
space group R (3) over bar shows a statistical distribution of ions La3+ Eu
3+, and Pb2+ over the positions 3a (occupation 10%) and 3b (occupation 90%)
of the so-called hll site, In agreement with these results, the Eu3+ lumin
escence analysis in these phases exhibits two sites for Eu3+, both are nonc
entrosymmetric, revealing a local disorder in the compounds, which is also
supported by the inhomogeneous broadening of the emission lines. The lumine
scence characteristics of this family of silicates have been investigated f
or various x values. Under excitation at 254 nm, the distinct emissions of
Pb2+ and of Eu3+ are observed, The excitation of Eu3+ ions occurs directly
via the charge transfer state or after Pb2+ --> Eu3+ energy transfer. Conce
ntration quenching of the Eu3+ emission is also investigated, (C) 1999 Acad
emic Press.