Effect of Eu3+ and Tb3+ ions concentration on the mechanical, structural, and photoluminescence properties of phosphate glass fibers

Two series of phosphate glasses belonging to the (65-x) P2O5-35CaO-xRE(2)O(3) system (RE = Eu or Tb; 0 <= x <= 6 mol%) were prepared by the melt-quenching technique. All compositions were successfully drawn as continuous monofilaments fibers. The effect of Eu3+ and Tb3+ ions concentration on their mechanical, structural, and photoluminescence properties was investigated. The results revealed that the highest tensile strength was 1031 +/- 34 MPa for fibers doped with 6 mol% of Eu2O3 and 1014 +/- 65 MPa for fibers doped with 6 mol% of Tb2O3. The addition of RE2O3 showed an increase in density and Tg. A structural investigation was carried out using FTIR spectroscopy. The photoluminescence properties in terms of excitation and emission spectra were investigated in detail. The most intense emission band at 611 nm corresponds to the D-5(0) -> F-7(2) transition of Eu3+ ions under 392 nm excitation was observed for fibers doped with 6 mol% of Eu2O3. The most intense emission band at 543 nm corresponds to the D-5(4) -> F-7(5) transition of Tb3+ ions under 374 nm excitation was observed for fibers doped with 6 mol% of Tb2O3. These two compositions exhibited the highest absolute quantum yield, reaching 20.25% and 4.81%, respectively.