•Er3+/Yb3+/Tm3+ co-doped zinc-tellurite glasses were synthesized by melt quenching method.•Effect of bridging and non-bridging oxygen on optical properties were investigated.•High polarizabilty ...around 2.71 × 10−24 cm−1 was found dependent of non-bridging oxygen.•Glasses can be utilized for plasmonics and optical amplifier applications.
Influence of Er3+, Yb3+ and Tm3+ on the network structure of zinc-tellurite glasses is investigated by refraction index and high-resolution X-ray photoelectron spectroscopy (XPS) in order to clarify the role of rare-earth ions in the formation of non-bridging and bridging oxygens (NBO and BO, respectively). The NBO atoms were responsible for high polarizability, as confirmed from the correlations between the local structure and polarizability, where have been tentatively established high linear fit r2=0.96 and 0.98 when the excitation wavelengths are 532 and 632.8 nm, respectively. The structural origin of the NBO atoms into the zinc-tellurites glasses is discussed by analysis of the component number from the deconvolution in the XPS spectra. In this analysis, Te 3d peaks shift by about 0.23 eV towards higher binding energy from TZ1 to TZ4, and spin-orbit splitting between Te 3d5/2 and Te 3d3/2 to all glasses remain unchanged, ΔE ≈10.4 eV. While Zn 2p peaks shift by about 1.08, eV towards higher binding energy, and spin-orbit splitting between Zn 2p3/2 and Zn 2p1/2 increase of 23.08 eV (TZ1 to TZ3) to 24.09 eV (TZ4) whit the increase REI. The O 1s spectra suggest that the increase of REI concentration produces additional environments for REI with bonds through lone-pair electrons, favoring the formation of NBOs. It was observed that the increasing the concentrations of REI has a high linear dependence with increased of NBO atoms in the glass network, r2=0.87.
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Optical thermometers offer several advantages when dealing with fast response, stability against external factors and high thermal sensitivity. In this paper, tellurite glasses doped with Er3+-Yb3+ ...were fabricated by conventional melt-quenching technique. Absorption, luminescence under 380, 488 and 980 nm excitation and decay lifetime measurements were carried out to analyse the emission performance of the glasses. Two-photons process of the Er3+ emission in the visible region were confirmed by analysing the excitation power and up-conversion intensities under 980 nm. The temperature sensing was investigated under different excitation processes, both up-conversion and down-shifting, using the fluorescence intensity ratio technique on the 2H11∕2 and 4S3∕2 thermally coupled levels in the range of 93–348 K. These glasses exhibit an excellent thermal response and high thermal sensitivities, turning them into propitious candidates for optical fibre and thermal sensing applications.
•Tellurite glasses doped with Er3+ and Yb3+ were synthesized with the melt-quenching technique.•The glasses were thermally and optically characterised.•The optical temperature sensing was studied using the FIR technique under different excitation processes.•High sensibilities were achieved with low Er3+ concentration.
The influence of different Germanium dioxide concentration on the structural, thermal, optical and spectroscopic properties of Er3+ doped tellurite glasses was carefully investigated. The glasses ...were prepared by melt-quenching technique. The samples were characterized by UV–visible–near-infrared spectroscopy, downshift emission spectroscopy, Raman spectroscopy, lifetime of green emission and up-conversion under near-infrared laser diode excitation at 975 nm. The Judd-Ofelt analysis was performed based on the absorption spectra of the glasses in order to obtain the Judd-Ofelt parameters (Ωλ), radiative transition rates, radiative lifetimes and quantum efficiency. The solubility of Er3+ into the host vitreous matrix, the enhancement in the luminescence intensity and improvement in the thermal stability (≥ 100 ∘C) of the glasses was verified on introducing GeO2.
•High refractive index that is suitable for photonic applications.•Considerable variations of Erbium's emission properties induced by the germanium incorporation in the host vitreous matrix.•Improvement of the optical quality for oxide-based glasses.•Systematic Judd-Ofelt's analysis for Er3+.•Favorable thermal stability making possible the fiber fabrication by preform thermal drawing.
Perovskite structures have attracted scientific interest as a promising alternative for water treatment due to their unique structural, high oxidation activity, electronic stability, and optical ...properties. In addition, the photocatalytic activity of perovskite structures is higher than that of many transition metal compounds. A critical property that determines the high-performance photocatalytic and optical properties is the band gap, lifetime of carrier charge, and band edges relative to the redox potential. Thus, the synthesis/processing and study of the effect on the band gap, lifetime of carrier charge, and band edges relative to the redox potential in the development of high-performance photocatalysts for water treatment are critical. This review presents the basic physical principles of optical band gaps, their band gap tunability, potentials, and limitations in the applications for the water treatment. Furthermore, it reports recent advances in the synthesis process and comparatively examines the band gap effect in the photocatalytic response. In addition to the synthesis, the physical mechanisms associated with the change in the band gap have been discussed. Finally, the conclusions of this review, along with the current challenges of perovskites for photocatalysis, are presented.
Abstract
It is crucial to control the tuning and improve the emission of a quantum emitter at the nanoscale. We report multiple Fano resonances in metallic nanostructures on an Er
3+
-doped tellurite ...glass. Periodic nanoslits were fabricated with a focused gallium ion beam on a gold thin film deposited on the tellurite glass. Is proposed a coupling function with Fano line-shape form, and the asymmetric parameter
q
for each resonance wavelength in the 515 to 535 nm region was calculated. This asymmetric resonance effect is a consequence of the quantum interaction between the continuum state, generated in the nanostructure, and the Stark splits of the
$$^2$$
2
H
$$_{11/2}$$
11
/
2
state.
Processes of energy transfer in Er3+–Tm3+ co-doped tellurite glasses has permitted to obtain an expanding broadband emission in the near-infrared region covering the bands S, C+L and U of the optical ...telecommunications and extending up to the 1700–1900nm range under excitation by a 976nm laser diode. This widening of the emission band is achieved through an integrated emission, where the Er3+ ions act as donor and the Tm3+ ions as acceptor following the route (Er3+)4I11/2→(Tm3+)3H5, (Er3+)4I13/2→(Tm3+)3H4 and (Er3+)4I13/2→(Tm3+)3F4. The relative intensity emission and lifetime of the 4I13/2→4I15/2 transition of the Er3+ ions decrease with increasing the Tm3+ concentration. Besides, high Tm3+ concentrations produce an emission quenching for the 3H4→3F4 and 3F4→3H6 radiative transitions, due to cross-relaxation between Tm3+ ions. These effects are studied by means of probability and quantum yield of the energy transfer. The most intense and widest emission band is measured in the glass co-doped with 0.075 and 1mol% of Tm2O3 and Er2O3, respectively.
•Broadband emission in the near-infrared region covering the bands S, C+L and U of the optical telecommunications.•This widening of the amplification band is achieved through an integrated emission Er3+–Tm3+.•Glass system arises from its potential applications as optical fiber amplifier or laser covering the entire telecommunications window.
Tellurite-tungsten glasses doped with Er3+-Pr3+ were fabricated by conventional melt-quenching, increasing the Pr2O3 content to enhance the emission performance and bandwidth of the 1.5 μm emission ...band. The spectroscopic properties in the visible and near-infrared regions are described, besides the Judd – Ofelt analysis of the Er3+. Results of the 1.5 μm emission intensity of the Er3+ under 980 nm, moreover the up-conversion emission, show an enhancement with the addition of Pr3+. Increments in the FWHM (≈ 90 nm) in the Er3+: 4I13/2 → 4I15/2 band are also reported, where the increment of Pr2O3 content plays an important role. The analyses of the dynamics between Er3+ and Pr3+ in these glasses comprehensively explain the Er3+ emission performance in the visible and near-infrared regions for optical communications applications.
•Tellurite - tungsten glasses doped with Er3+ and Pr3+ were fabricated with the melt-quenching technique and investigated.•Luminescence quenching of the emission of Er3+ was obtained due to the presence of Pr3+.•FWHM increments of the 1.5 μm emission band with the addition of Pr3+ were observed.•The dynamics between Er3+ and Pr3+ is discussed.
•Melt-quenching method was employed to prepare Pr3+-Er3+-codoped tellurite glasses.•XPS confirms the valence states of Te, Zn, Pr, and W.•The correlation between polarizability and the bridging to ...non-bridging oxygen ratio is established.•The nonlinear refraction index was enhanced by increasing Pr3+ ions.
In this investigation, we systematically probe the structural, optical, and, notably, the nonlinear optical properties of Pr3+-Er3+-codoped tellurite glasses to understand the potential new functionalities of the glass and, thus, their applicability. The glass samples were synthesized employing the melt-quenching technique and subsequently characterized using X-ray photoelectron spectroscopy (XPS) and femtosecond (fs) pulse Z-scan measurements at 720 and 750 nm wavelengths. XPS analyses unveiled increased non-bridging oxygens (NBO) with ascending Pr2O3 content. It was observed that the increasing concentrations of Pr3+ ions show a linear dependence with the increase of NBO in the glass network (r2 > 0.95). This trend further supported the formation of Te3+ ions via the oxidation of Te4+ for charge compensation and was affirmed by a decrement in average TeO bond as Pr2O3 concentrations increased. The tellurite glasses showcased positive nonlinear refraction on the nonlinear optical (NLO) front. The rise in n2 values was directly linked to the Pr2O3 content, a phenomenon attributed to the increased presence of non-bridging oxygens and the inherent polarizability of Pr3+ ions. Collectively, our findings offer pivotal insights into the modulation of NLO attributes in Er3+-doped tellurite glasses via Pr3+ ion doping, underscoring their potential in advanced NLO device applications.
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We report a comprehensive discussion of quantum interference effects due to the finite structure of neutral excitons in quantum rings and their first experimental corroboration observed in the ...optical recombinations. The signatures of built-in electric fields and temperature on quantum interference are demonstrated by theoretical models that describe the modulation of the interference pattern and confirmed by complementary experimental procedures.
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