Abstract
Sodium phosphate glasses co-doped with Eu3+/Ag NPs were prepared by the melt quenching method. A thermal annealing process is proposed to control the aggregation and growth of Ag NPs. The amorphous nature is confirmed by the x-ray diffraction patterns for all the glasses. TEM picture analyses revealed the presence of silver nanoparticles of almost spherical shape and various sizes inside the glass matrix depending on the annealing time. The absorption spectra revealed seven absorption peaks of Eu3+ions in addition to the surface Plasmon resonance (SPR) band of Ag NPs centered at 400 nm. The luminescence properties of Eu3+ doped phosphate glass containing silver nanoparticles (NPs) are investigated. The observed enhancement of the photoluminescence and the PL lifetime relative to 5D0→7F2 transitions are explained not only by the energy transfer ions, but NPs to Eu3+ ions but also by the enhancement of local field effect LFE induced by SPR of silver NPs. Based on the emission spectra, Judd Offelt (JO) parameters (Ω2 and Ω4), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors, the quantum yield of luminescence and the stimulated cross-section emissions for 5D0→7F2 transition are calculated. The fluorescence quantum efficiencies are found to be enhanced with the increase of heat treatment until it attains 85% for the sample PAZE20. The results indicated that the heat-treated glass for 20 h has a good prospect as a gain medium applied for 615 nm broadband and high-gain europium-doped fiber amplifiers.
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•Eu3+/Ag co-doped phosphate glasses were synthesized using melt quenching method.•TEM pictures reveal the presence of Ag nanoparticles where the sizes depend on annealing time.•The fluorescence enhancement is attributed to localized electric field by metal.•High quantum efficiency, up to 85%, is reported after 20 h of heat treatment.