Structure-property relations in new fluorophosphate glasses singly- and co-doped with Er3+ and Yb3+

New fluorophosphate glasses co-doped with Eu3+ and Tb3+ as candidates for generating tunable visible light

“…The blue emissions are not observed with significant intensity in oxide glasses due to characteristic high phonon energies, which are responsible for the depopulation of Tb 3+ excited levels via multiphonon decay. In the fluorophosphates glasses investigated here, despite the fact that the high maximum phonon energy of 1100 cm -1 is still determined by the vibrations of phosphate units [32], previous work on Er 3+ and Yb 3+ doped glasses has given strong evidence of the preferential binding of the RE ion to F - [19].…”

“…In Er 3+ -doped and Er 3+ /Yb 3+ co-doped samples (0.25 -5.0 mol% REF3) significant improvement of radiative properties (increased lifetime and fluorescence quantum efficiencies values) was verified as compared to other phosphate and fluorophosphate compositions. Such improvements were attributed to a clear bonding preference between aluminum and phosphorus, consistent with the desired predominance of fluoride species in the local environment of the RE and alkaline ions, as evidenced by solid state NMR of the constituent nuclei [19].…”

“…A weight loss of 7-10% from the initial batch was verified for the final samples. A quantitative study by solid state NMR indicated that approximately 80% of the initial fluorine content is retained in final samples, while the remaining 20% is exchanged by water or oxygen from the furnace atmosphere [19].…”

“…Despite the fact that oxide glasses such as silicates, borates and phosphates present superior mechanical, chemical and thermal stabilities, and can disperse higher RE concentrations than fluoride glasses, the latter exhibit higher phonon energies and OH -M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 3 fluoride network by insertion of PO4 groups [19]. On the other hand, the decreased presence of OH -groups, typical of the fluoride network, results in a more favorable environment for the emitting RE ions.…”

“…On the other hand, the decreased presence of OH -groups, typical of the fluoride network, results in a more favorable environment for the emitting RE ions. With that in mind, we have recently reported detailed structural and spectroscopic investigations of new fluorophosphate glasses in the compositional system BaF2-SrF2-Al(PO3)3-AlF3-YF3 doped with Er 3+ and/or Yb 3+ [19,20].…”