Jean Fava

Transfert d'energie entre les ions Ce3+ et Tb3+ dans GdAlO3

Abstract Energy transfer from the Ce 3+ to the Tb 3+ ion has been studied in a host GdAlO 3 structure. The maximum fluorescence intensity of Tb 3+ is observed for the composition Gd 0.96 Ce 0.02 Tb 0.02 AlO 3 . The energy transfer from Ce 3+ to Tb 3+ is explained by a dipole-dipole type coulombic interaction.

Les phases SrLa2Al2O7 et SrGd2Al2O7

Abstract SrLa2Al2O7 and SrGd2Al2O7 belong to the structural type Sr3Ti2O7. In SrGd2Al2O7 strontium and gadolinium occupy respectively the 12 and 9 coordinated sites, whereas in SrLa2Al2O7 the homologous cations are statistically distributed. The fluorescence spectra of both phases activated by Eu3+ ions show that the only possible position of Eu3+ is the 9 coordinated site.

Elaboration et proprietes optiques de nouveaux verres fluores actives au neodyme

A vitreous domain has been investigated in the quaternary system BaF2CaF2AlF3BeF2. Several optical properties have been reported for a typical composition range Ba15Ca27−xNdxAl31Be27F231+x with 0 ≤ x < 8: refractive index, adsorption and fluorescence spectra, oscillator strengths and fluorescence life time. These properties have been compared with those of other glasses previously proposed as laser host structures. The performances are among the best so far obtained for such applications.

On some new efficient luminophors with low-concentration quenching effects

Abstract New phosphors very efficient under uv excitation Na 3 Ce 1− x Tb x (PO 4 ) 2 and Na 3 La 1− x Gd x (PO 4 ) 2 , have been proposed. The high resolution emission of Gd 3+ in Na 3 Gd(PO 4 ) 2 and the non-radiative energy transfer from Gd 3+ to Tb 3+ in Na 3 Gd 1− x Tb x (PO 4 ) 2 have been studied.

Etude radiocristallographique et par resonance Mössbauer de CaLaFeO4

Abstract CaLaFeO 4 has a K 2 NiF 4 type structure. Its critical exponent β determined by Mossbauer spectrometry shows a crossover at T / T N = 0, 955.

Mise en evidence d'un transfert d'energie de type Gd3+ → Tb3+ dans les phases Sr2Gd1−xTbxGaO5

Abstract Energy transfer from optically excited Gd 3+ ions to Tb 3+ ions is reported in Sr 2 Gd 1−x Tb x GaO 5 . It is illustrated by the comparison of the emission and excitation spectra of Sr 2 GdGaO 5 and of Sr 2 Gd 0,995 Tb 0,005 GaO 5 between 77 and 300 K.

Proprietes optiques et distribution cationique de la phase CaLa1-xGdxGao4α(0 ⩽ x ⩽ 1)

Abstract The luminescence of Gd 3+ in CaLa 1−x Gd x GaO 4 α , which is olivine type structure, is reported. Additional information on the crystal structure can be deduced from the emission and excitation spectra : the Ca 2+ and Gd 3+ ions are randomly distributed in the (4a) and (4c) sites. Furthermore the thermal variation of spectral energy distribution of the emission may be explained by a Gd 3+ → Gd 3+ energy transfer from (4c) to (4a) sites. The 6 P 7 2 and 6 P 5 2 energy levels are discussed on the base of crystal chemical considerations.