Relationships between structural and luminescence properties in Eu3+-doped oxyphosphate–silicate apatite Ca2+xLa8−x(SiO4)6−x(PO4)xO2

Structural and Spectroscopic Characterization of Nominal Yb3+:Ca8La2(PO4)6O2 Oxyapatite Single Crystal Fibers Grown by the Micro-Pulling-Down Method

“…La(II) is the more likely of the two as it corresponds to identical cationic charges and also to the lowest symmetry, allowing optical transitions with the highest probability. The same kind of assignment has been proposed for Eu 3+ -doped CLPA [15] for the 5 D 0 ® 7 F 0 highest intensity line, [15] but in that case three distinct lines were detected and naturally associated with the three types of sites. It is difficult to say more about the proportions of multisite occupation in CLYPA due to the difficulty of resolving ªAº and ªBº electronic and vibronic transitions of each type of center.…”

“…A recent article has shown multicenters with the use of Eu 3+ structural probe luminescence spectroscopy. [15] Three types of Eu 3+ sites have been detected from 5 D 0 ® 7 F 0 transitions both from Ca 2+ and La 3+ substitutions due to similar ionic radii with those of Eu 3+ ion and, also, based on the existence of the two kinds of cationic sites labeled M(I) and M(II), corresponding to the (4f) and (6h) positions of the M 10 (PO 4 ) 6 0 2 oxyapatite structure in the hexagonal system. M(I) has trigonal point symmetry (C 3 ) with nine oxygen anions.…”

“…In Ca 8 La 2 (PO 4 ) 2 0 2 as host, it has been shown that the M(II) positions in C s symmetry could be occupied by 2 La 3+ and 4 Ca 2+ ions and then the M(I) sites are occupied by 4 Ca 2+ cations in C 3 symmetry. [15] Consequently, we can think that Yb 3+ ions should mainly substitute the Ca(II) crystallographic site, which is characterized by the highest population with the lowest symmetry and thus, by the highest emission probability. The two 0-lines of Figure 8 should be connected with at least two of the three crystallographic sites, two types of M(II) and one type of M(I) site.…”

Luminescent properties of Eu-doped germanate apatite Sr2La8(GeO4)O2

“…Consequently, for the Sr 2 La 8 (GeO 4 ) 6 O 2 host, all of the 6h sites are occupied by six La(2) ions, and the 4f sites by both La(1) and Sr (1) ions. Previous studies on the crystallographic positions of Eu 3+ ions in Ca 2 La 8 (SiO 4 ) 6 O 2 demonstrate that Eu 3+ cations occupy only two sites labeled Ca(1) (4f) C 3 symmetry and La(2) (6h) C s symmetry ions [14]. Therefore, it is believe that the Eu 3+ ions occupy 4f and 6h sites in Sr 2 La 8 (GeO 4 ) 6 O 2 .…”

Solubilité de l'uranium dans les solutions solides d'apatite phospho-silicatée

“…Matériaux pour l'optique : industrie de la technologie, lampes fluorescentes, composants d'écrans de télévision en couleur et matériau laser [2][3][4][5] Industrie nucléaire : matrices de confinement des éléments radioactifs et des produits de fission [6][7][8] Figure 2 Evolution des diffractogrammes des rayons X en fonction de la teneur en uranium (P04/S104-1) D'après la Figure 2, on peut remarquer qu'en dessous de 4 % en uranium, toutes les raies du diffractogramme de rayons X sont indexées dans le système hexagonal propre à la structure apatitique. A…”