Spectroscopic properties of neodymium doped magnesium zinc sulfophosphate glass: synergistic effects of titanium and silver nanoparticles embedment

Synergistic effects of two distinct metal/semiconductor nanoparticles (NPs) upon incorporation into different materials medium have shown to open up a new frontier in material research. In this view, two series of neodymium ions (Nd3+) doped magnesium zinc−sulfo phosphate glass glasses composition 58.5P2O5–20MgO–20ZnSO4–1.5Nd2O3–0.5AgNPs−yTi NPs (where y = 0.1, 0.2, 0.3 and 0.4 mol% in excess) and 58.5P2O5–20MgO–20ZnSO4–1.5Nd2O3–0.4TiNPs−xAg NPs (where x = 0.1, 0.2, 0.3, 0.4 and 0.5 mol% in excess) were prepared via melt−quenching method. The as-synthesized samples were characterized to determine the combined effects of silver (Ag)/titanium (Ti) NPs inclusion on their spectroscopic properties. XRD analyses of as-quenched samples confirmed their amorphous nature. The FTIR and the Raman spectra revealed the presence of characteristic vibration bonds inside the studied glass network. The HRTEM images verified the nucleation of both Ag and Ti3O5 NPs inside the host matrix. The occurred twelve absorption bands centred at 352, 430, 458, 473, 512, 526, 582, 626, 682, 745, 802 and 875 nm were assigned to the respective transitions from the ground state (4I9/2) to the excited states of 2D1/2+4D3/2+4D5/2, 2P1/2, 4G11/2, 2D3/2+2P3/2+2G9/2, 4G9/2+2K13/2, 4G7/2, 4G5/2+2G7/2, 2H11/2, 4F9/2, 4F7/2+4S3/2, 4F5/2+2H9/2 and 4F3/2 in Nd3+. The probed surface plasmon resonance (SPR) band of Ag NPs (at 442 nm) and Ti3O5 NPs (at 585 and 730 nm) indicated their successful embedment within the glass matrix. Meanwhile, the SPR bands of both NPs disclosed a slight red−shift when embedded together inside the glass compared to their individual incorporation which was ascribed to the near field effect mediated alteration in natural frequency of the oscillator. The observed prominent yellow band around 585 nm in the photoluminescence (PL) spectra of glasses was approved to the transition of 2G7/2+4G5/2 → 4I9/2. The NIR PL spectra depicts bands around 874 nm, 1050 nm and 1322 nm, corresponding to 4F3/2 → 4I9/2, 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 transitions respectively. The evidenced PL intensity quenching in the glass prepared bands around with both Ag and Ti3O5 NPs was attributed to the effect of metallic NPs mediated local heating. Judd-Ofelt (JO) theory was used to evaluate the spectroscopic properties of the glass and make contact with experimental findings. Sample embedded with 0.4 mol% of Ti NPs together with 0.3 mol% of Ag NPs showed highest stimulated emission cross−section (4.78 × 10−24 cm2) for transition 2G7/2+4G5/2 → 4I9/2. It was established that the synergistic effects of two types of metal NPs embedded inside the Nd3+ doped proposed host glass may be useful to achieve customized spectroscopic properties required for solid state laser and photonic application