Europium ions and silver nanoparticles co-doped magnesium-zinc-sulfophosphate glasses: Evaluation of ligand field and Judd-Ofelt parameters

Abstract

This paper reports the ligand field and Judd-Ofelt analyses of europium ions (Eu3+) and silver nanoparticles (AgNPs) activated magnesium-zinc-sulfophosphate glasses. Such glasses of composition 63.5P2O5–20MgO–15ZnSO4–1.5Eu2O3–yAgNPs (y = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.1 g in excess) were prepared via melt quenching method and characterized by different analytical tools. The feasibility of achieving a novel glass based efficient red laser and light emitting diodes (LEDs) was explored. XRD analyses of as-quenched samples verified their glassy character. UV–Vis–NIR absorption spectra of the studied glasses displayed eight peaks at 360, 380, 394, 414, 465, 531, 2091 and 2205 nm allocated to the 7F0→5L6,7F0→5G4,7F1→5L6,7F1→5D3, 7F0→5D2,7F1→5D17F6→7F0 and 7F1→7F6 transitions in the Eu3+. Observed improvement in the photoluminescence intensity associated to 5D0→7F2 transition was majorly attributed to the energy transfer among Eu3+ and AgNPs enabled localised surface plasmon resonance induced local field effects. TEM analysis confirmed the uniform dispersion and nucleation of AgNPs (average diameter ≈27.65 nm) in the glass matrix. Judd-Ofelt analyses were performed to calculate the intensity parameters (Ω2, Ω4 and Ω6) and radiative properties wherein the experimental optical data were utilized. For the studied glasses, the disclosed trend of Ω2˃Ω4 validated their ionic character and high symmetry environment around Eu3+. Proposed glass composition revealed excellent values of optical gain 2.82×10−25cm2S−1 to 20.81×10−25cm2S−1 and branching ratio (4.33–75.8%). Optimum values of critical laser parameters for 5D0→7F2 transition in MZSPEAg1.1 g glass was 20.8 × 10−25 cm2 s−1 for the optical gain and 21.1×10−22cm2 for gain bandwidth. Furthermore, the Racah parameters calculated from the first three significant visible absorption bands were reduced from 82.85×cm−1 to 72.33×cm−1 with the increase in AgNPs contents (from 0.1 to 1.1 g), signifying the weakening in f-f electrons repulsion. It was asserted that the proposed glass composition may contribute towards the development of solid-state laser and LEDs.