The effect of CdS addition on linear and non-linear refractive indices of glasses in the system TeO2/Nb2O5/ZnO

Glasses in the system TeO₂/Nb₂O₅/ZnO/CdS were studied with respect to the density, molar volume, refractive index, polarizability, molar refraction, metallization and third order non-linear optical susceptibility. The third order non-linear optical susceptibilities, χ⁽³⁾, were measured using degenerate four-wave mixing (DFWM). The addition of CdS to TeO₂-based glasses leads to increasing refractive as well as the non-linear refractive indices. The largest measured value of the third order non-linear optical susceptibility was 7.8 × 10^?13 esu and has been found in the 90TeO₂ · 5Nb₂O₅ · 5ZnO · 0.4 CdS glass. The non-linear optical susceptibility increased with increasing CdS-concentration. In order to estimate the third order non-linear optical susceptibility, the theoretical model of Lines and the empirical equation of Miller were used.     

Preparation and characterization of CuO doped Bi2O3–B2O3–BaO–ZnO glass system for transparent dielectric layer

The electrical, thermal, optical, and morphological properties of CUO doped Bi₂O₃–B₂O₃–BaO–ZnO glasses were studied as a PbO-free, low firing transparent dielectric layer for plasma display panels (PDP). CuO improved the transmittance of Bi₂O₃–B₂O₃–BaO–ZnO by up to 84% in the visible region, eliminating a yellowish color typical of Bi₂O₃–B₂O₃–BaO–ZnO. A slight absorption within the near infrared (NIR) region was also observed. The glass transition temperature (T_g), thermal coefficient of expansion (TCE), and root-mean square (rms) roughness of 0.005 wt% CuO doped Bi₂O₃–B₂O₃–BaO–ZnO were found to be 455 °C, 81.4 × 10⁻⁷/K, respectively, and 162 ± 14 Å, which satisfied the requirements for a transparent dielectric layer for PDP application.     

Laser spectroscopy of Nd3+-doped PbO–Bi2O3–Ga2O3–BaO glasses

We present spectroscopic results of PbO–Bi₂O₃–Ga₂O₃–BaO glass doped with different concentration of Nd₂O₃. These glasses have high refractive index (∼2.4) and large spectral transmission window. Measurements of absorption, emission and fluorescence lifetime are presented. From the calculations of the Judd–Ofelt parameters the radiative lifetimes, branching ratios and quantum efficiency of ⁴F_3/2 level are calculated. The highest emission intensity was measured for the sample doped with 0.5 wt% of Nd₂O₃ with emission cross-section of 2.6 × 10⁻²⁰ cm², at 1069 nm, fluorescence lifetime of 110 μs, quantum efficiency of 82% and effective linewidth of 34 nm. The results point out this glass system as good candidate to be used in the development of photonic devices operating in the near infrared spectral range.     

Properties and structure of Yb3+ doped zinc aluminum silicate phosphate glasses

This study explores a series of optical, thermal, and structural properties based on 60P₂O₅–30ZnO–10Al₂O₃ (60P) glasses that doped with varied rare earth (RE) elements Yb₂O₃ and P₂O₅ components replaced by SiO₂. It was found that the glasses density decrease with SiO₂ concentration added to replace P₂O₅, whereas they increase with increased concentration of Yb³⁺-doped. Moreover, the glasses transition temperature, softening temperature, and refractive index increase with Yb³⁺ concentrations added, whereas the thermal expansion coefficient decreases. For the 60P glasses, 7 mol% Yb₂O₃ doped has the maximum fluorescence which is suppressed when Yb₂O₃ is doped up to 9 mol%. In addition, maximum lifetime was found to be 2.68 ms at an optimal Yb³⁺-doping at 1 mol% for 53P₂O₅–7SiO₂–30ZnO–10Al₂O₃ glass.     

Thermal lens study of PbO–Bi2O3–Ga2O3–BaO glasses doped with Yb3+

The aim of this paper is to present a study of the thermal lens technique in quantifying the thermo optical coefficients: ds/dT (optical path change with temperature), thermal diffusivity and conductivity of PbO–Bi₂O₃–Ga₂O₃–BaO glasses doped with Yb³⁺. The thermal lens results indicate that the heat generation, as a function of the incident wavelength, resembles the absorption band ²F_7/2 → ²F_5/2 of Yb³⁺. Thermal diffusivity of 2 × 10⁻³ cm²/s and thermal conductivity of 4.5 × 10⁻³ W/K cm were obtained and are similar to other glasses already reported in previous literature. The results emphasize that the thermal lens technique can be a powerful tool to study the heat generation of new glassy systems.     

Fabrication and characterization of Er3+-doped GeO2–PbO and GeO2–PbO–Bi2O3 glass fibers

Glass fibers were drawn from GeO₂–PbO–Bi₂O₃ and GeO₂–PbO melts previously doped with Er³⁺. From the differential thermal analysis curve, the glass transition temperature was determined to be 420 °C, and no crystallization peak was observed in the temperature range of that analysis, indicating stability with regard to devitrification. Raman spectroscopy was performed to characterize the structure of the glasses, which exhibited large transmission windows (0.5–5.0 μm) and large refractive indices (∼2.0). Infrared to visible upconversion of Er³⁺ was observed in the fibers. The visible emissions were related to the upconverted green emissions at about 530 nm (²H_11/2 → ⁴I_15/2) and 550 nm (⁴S_3/2 → ⁴I_15/2), and red emission at 668 nm (⁴F_9/2 → ⁴I_15/2) under 980 nm excitation. The infrared transition (⁴I_13/2 → ⁴I_15/2) was peaked at 1.53 μm. The results obtained suggest that the fibers exhibit the same structures as the parent glasses and can be used in upconversion fiber optical devices.     

Redox reactions during temperature change in soda-lime–silicate melts doped with copper and iron or copper and manganese

Glasses with the base composition 16Na₂O · 10CaO · 74SiO₂ doped with copper and iron or copper and manganese were studied by high temperature UV–vis–NIR spectroscopy. The spectra exhibited distinct absorption bands attributed to the respective transition metal ions present (Cu²⁺, Fe²⁺, Fe³⁺, Mn³⁺). In glasses doped with only one polyvalent element, the absorption decreases linearly with increasing temperature, the absorption bands are shifted to smaller wave numbers and get broader. In glasses doped with two types of transition metals, the situation is the same up to a temperature of around 550 °C. At larger temperature, the Cu²⁺-absorption in glasses also co-doped with iron increases again, while in glasses doped with both copper and manganese the absorption is approximately the same as in glasses solely doped with copper. It is shown that this is due to redox reactions between polyvalent species. These reactions are frozen in at temperatures <550 °C.     

EPR and magnetic susceptibility studies of B2O3–Bi2O3–Gd2O3 glasses

Glasses of the xGd₂O₃ · (100 − x)[B₂O₃ · Bi₂O₃] system with 0.5 ⩽ x ⩽ 10 mol% were studied by electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. Data obtained show that for low gadolinium oxide contents of the samples (x ⩽ 3 mol%) the Gd³⁺ ions are randomly distributed in the host glass matrix and are present as isolated and dipole–dipole coupled species. For higher gadolinium oxide contents of the samples (x > 3 mol%) the Gd³⁺ ions appear as both isolated and antiferromagnetically coupled species. The EPR spectra of the glasses reveal resonance sites with an unexpected high crystalline field in addition to the ‘U’ spectrum, typical for Gd³⁺ ions in disordered systems. This absorption line is due to Gd³⁺ ions that replace Bi³⁺ ions from the host glass matrix and could play the network unconventional former role in the studied glasses.     

Properties and structure of (1 − x)Li2O–xNa2O–Al2O3–4SiO2 glass systems

(1 − x)Li₂O–xNa₂O–Al₂O₃–4SiO₂ glasses were studied for the progressive percentage substitution of Na₂O for Li₂O at the constant mole of Al₂O₃ and SiO₂. The crystallization temperature at the exothermic peak increased from 898 to 939 °C when the Na₂O content increases from 0 to 0.6 mol. The coefficient of thermal expansion and density of these as-quenched glasses increase from 6.54 × 10⁻⁶ °C⁻¹ to 10.1 × 10⁻⁶ °C⁻¹ and 2.378 g cm⁻³ to 2.533 g cm⁻³ when the Na₂O content increases from 0 to 0.4 mol, respectively. The electrical resistivity has a maximum value at Na₂O · (Li₂O + Na₂O)⁻¹ = 0.4. The activation energy of crystallization decreases from 444 to 284 kJ mol⁻¹ when the Na₂O content increased from 0 to 0.4 mol. Moreover, the activation energy increases from 284 kJ mol⁻¹ to 446 kJ mol⁻¹ when the Na₂O content increased from 0.4 to 0.6 mol. The FT-IR spectra show that the symmetric stretching mode of the SiO₄ tetrahedra (1035–1054 cm⁻¹) and AlO₄ octahedra (713–763 cm⁻¹) exhibiting that the network structure is built by SiO₄ tetrahedra and AlO₄.     

Bond character,optical properties and ionic conductivity of Li2O/B2O3/SiO2/Al2O3 glass: Effect of structural substitution of Li2O for LiCl

A glass of composition (20 ? x)Li₂O–xLiCl–65B₂O₃–10SiO₂–5Al₂O₃ where 0 ? x ? 12.5 wt% is prepared using the normal melt-quenching technique. The optical constants and electrical conductivity and their correlation are investigated, furnished and discussed with the substitution of Li₂O for LiCl. The mechanism of the optical absorption and the calculated Urbach energy follow the rule of phonon-assisted transitions. The ionic conduction mechanism is determined by activation energy process. Substitution up to 10 wt% LiCl provides high ionic conductivity (1.9 × 10^?2 Ω^?1 m^?1) due to the high average electronegativity of LiCl which increases the polarizability of lithium ions. The small cation–anion distance approach confirmed the enhancement in ionic conductivity of LiCl containing glass compared to that of Li₂O. Due to the large size of Cl^? ions, there is an expansion of the lattice which in turn broadens the available path windows. For 12.5 wt% LiCl, anomalous density behavior is observed and a reduction in conductivity is occurred, σ = 5.4 × 10^?3 Ω^?1 m^?1. Owing to the model of bond fluctuation, the reduction is attributed to the increase in the alkali halide concentration which creates bottlenecks that hinder the motion of Li⁺ ions. The ionic conductivity character is strongly supported by the behavior of the glass ionicity factor, density, molar volume, refractive index, average boron–boron separation, molar refraction, metallization criterion and non-bridging oxygen concentration of the studied glass.     

Optical properties of Er3+-singly doped and Er3+/Yb3+-codoped novel oxyfluoride glasses

Novel oxyfluoride glasses SiO₂–Al₂O₃–Na₂O–ZnF₂ doped with Er³⁺ and Er³⁺/Yb³⁺ were fabricated. The optical properties of the synthesized glasses were experimentally and theoretically investigated in detail. The experimental and calculated oscillator strengths of Er³⁺ were determined by measurement of the absorption spectrum of Er³⁺-singly doped glass. According to the Judd–Ofelt theory, the experimental intensity parameters were calculated, from which the radiative transition probabilities, fluorescence branching ratios and radiative lifetimes were obtained. The fluorescence lifetime and quantum efficiency for the near-infrared emission of Er³⁺-singly doped glass were determined to be 3.0 ms, and 42%, respectively. Visible upconversion luminescence was observed under 980 nm diode laser excitation. The dependence of the upconversion emission intensity upon the excitation power was examined, and the upconversion mechanisms are discussed.     

EPR and optical studies of Mn2+ ions in Li2O–Na2O–B2O3 glasses – An evidence of mixed alkali effect

EPR and optical absorption spectra of 0.5 mol% MnO₂ doped xLi₂O–(30 − x)Na₂O–69.5B₂O₃ (5 ⩽ x ⩽ 25) glasses have been studied. The EPR spectra exhibit resonance signals characteristic of Mn²⁺ ions. The resonance signal at g ≅ 2.0 is due to Mn²⁺ ions in an environment close to octahedral symmetry, whereas the resonances at g ≅ 4.3 and g ≅ 3.3 are attributed to the rhombic surroundings of the Mn²⁺ ions. The ionic character (A), the number of spins participating in resonance (N), optical band gap energies (E_opt) and Urbach energies (ΔE) show the mixed alkali effect (MAE) with composition. The present study gives an indication that the size of alkalis we choose, is also an important contributing factor in showing the MAE. The variation of N with temperature obeys the Boltzmann law. The optical absorption spectra show a single broad band at ∼21 000 cm⁻¹ corresponding to the transition ⁶A_1g(S) → ⁴T_1g(G) which exhibits a blue shift with x. The theoretical values of optical basicity (Λ_th) have also been evaluated.     

Characterization of B2O3 and/or WO3 containing tellurite glasses

Characterization of B₂O₃ and/or WO₃ containing tellurite glasses was realized in the 0.80TeO₂–(0.20 ? x)WO₃ ? xB₂O₃ system (0 ≤ x ≤ 0.20 in molar ratio) by using differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectrometry techniques. Glasses were prepared with a conventional melt-quenching technique at 750 °C. To recognize the thermal behavior of the glasses, glass transition and crystallization temperatures, glass stability value, glass transition activation energy, fragility parameter were calculated from the thermal analyses. Density, molar volume, oxygen molar volume and oxygen packing density values were determined to investigate the physical properties of glasses. Fourier transform infrared spectra were interpreted in terms of the structural transformations on the glass network, according to the changing B₂O₃ and/or WO₃ content. Crystallization behavior of the glasses was investigated by in situ X-ray diffraction measurements and microstructural characterization was realized by scanning electron microscopy and energy dispersive X-ray spectrometry analyses.     

Thermal properties and glass formation in the SiO2–B2O3–Bi2O3–ZnO quaternary system

Lead-free glasses in the SiO₂–B₂O₃–Bi₂O₃–ZnO quaternary system were studied. The glass formation region, as determined by XRD patterns of bulk samples, was limited to glasses having more than 40 mol% of the glass-forming oxides SiO₂ and B₂O₃. Crystalline phases of Zn₂SiO₄ (willemite) were detected in compositions of 30SiO₂ · 10B₂O₃ · 20Bi₂O₃ · 40ZnO and 20SiO₂ · 10B₂O₃ · 25Bi₂O₃ · 45ZnO. Glass transition temperatures (T_g), dilatometric softening points (T_d) and linear coefficients of expansion in the temperatures range of 25–300 °C (α_25–300) were measured for subsystems along the B₂O₃ join of 10, 20 and 30 mol%. For these subsystems, T_g ranged from 411 to 522 °C, and T_d ranged from 453 to 563 °C, both decreasing with increasing Bi₂O₃ content. The measured α_25–300 ranged from 53 to 95 × 10⁻⁷ °C⁻¹, with values increasing with increasing Bi₂O₃ content. The ZnO content had the opposite effect to the Bi₂O₃ content. It appears that Bi³⁺ acts as a glass-modifier in this quaternary system.     

Thermal and spectroscopic properties of Tm3 + doped TZPPN transparent glass laser material

In this work a transparent bulk glass with the mol% composition 76TeO₂·10ZnO·9.0PbO·1.0PbF₂·3.0Na₂O doped with Tm^3 + has been synthesized. Results of differential thermal analysis (DTA) indicate a high thermal stability and low tendency to crystallization of this glass. The refractive indices at different wavelengths, the Urbach energy, the optical energy gap, the Sellmeier gap energy and the dispersion energy have been estimated. Spectroscopic quality factor of Tm^3 + was evaluated from optical absorption spectra. Electric and magnetic dipole transition probabilities, branching ratios, and radiative lifetimes of several excited states of Tm^3 + have been predicted using calculated intensity Judd–Ofelt parameters. The classical McCumber theory has been applied to evaluate the emission cross-sections for ³F₄ → ³H₆ transition around 1.8 μm. This study shows that TZPPN glass doped with Tm^3 + ions is a promising candidate for laser applications.     

Spectroscopic properties and energy transfer in Ga2O3– Bi2O3–PbO–GeO2 glasses codoped with Tm3+ and Ho3+

This paper reports on the spectroscopic properties and energy transfer in Ga₂O₃–Bi₂O₃–PbO–GeO₂ glasses doped with Tm³⁺ and/or Ho³⁺. From the optical absorption spectra of Tm³⁺, Judd–Ofelt intensity parameters, radiative transitions probabilities, fluorescence branching ratios, and radiative lifetimes have been calculated using Judd–Ofelt theory. The measured differential scanning calorimetry result shows that the glass exhibits excellent stability against devitrification with ΔT = 129 °C. The measured luminescence spectra show that the ³H₄ → ³F₄ transition of Tm³⁺ upon 808 nm laser diode excitation possess a broad full width at half-maximum of ∼126 nm. The maximum value calculated stimulated emission cross-section and the measured lifetime of ³H₄ level from the 1.47-μm transition are ∼4.73 × 10⁻²¹ cm² and ∼0.239 ms, respectively. It is noticed that codoping of Ho³⁺ could significantly enhanced the ratio of the intensity of 1.47–1.80 μm by energy transfer via Tm³⁺: ³F₄ → Ho³⁺: ⁵I₇.     

Dissolution behavior of ZnO–P2O5 glasses in water

Bulk binary ZnO–P₂O₅ glasses with 50–70 mol% ZnO were immersed in distilled water at 30–90 °C for up to 72 h. The immersed samples were characterized by weight loss, the change in solution pH, X-ray diffraction (XRD) analysis, scanning electron microscopy and Raman spectroscopy. Weight loss decreased with ZnO concentration for all immersion temperatures. Dissolution behavior was classified into two types in terms of weight loss and macroscopic appearance. Type I was primarily recognized in 50–60 mol% ZnO glasses. In type I, the weight loss for 72 h was relatively large (>1.0 × 10⁻⁷ kg mm⁻², >10% of initial sample weight). Raman spectra of the type I glasses indicated that the depolymerization of phosphate glass network occurred during the dissolution process. Crystalline Zn₂P₂O₇ · 3H₂O was precipitated in the water solution after immersion. Type II dissolution behavior was recognized in the 65 and 70 mol% ZnO glasses except for the 65ZnO–35P₂O₅ glass immersed at 90 °C. In the type II behavior, the weight loss for 72 h was relatively-small (<1.0 × 10⁻⁸ kg mm⁻², <1% of initial sample weight). The microstructure of the type II glass indicated selective dissolution. The dissolution process of the type II glass is discussed.     

Synthesis and structural characterization of P2O5–CaO–Na2O sol–gel materials

Ternary phosphate-based glasses in the system P₂O₅–CaO–Na₂O were synthesized using the sol–gel approach. Glasses in this system have the potential for use as bioactive materials. A mixture of mono- and dialkyl phosphate PO(OH)_3−x(OC₂H₅)_x (x = 1, 2) and alkoxides of sodium and calcium in an ethylene glycol solution were used as precursors. One of the compositions has also been synthesized by sonocatalysis (application of ultrasonic vibration to the sol). The systems synthesized, which remain fully amorphous even after calcination at 400 °C given the appropriate composition, have been characterized using X-ray diffraction (XRD). Thermal properties have been examined by means of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The structure of the phosphate network has been studied as a function of composition using Fourier transform infrared spectroscopy (FT-IR) and ³¹P MAS NMR.     

Structural investigations of sodium diborate glasses containing PbO,Bi2O3 and TeO2: Elastic property measurements and spectroscopic studies

Pseudo-binary sodium borate glasses containing (1 − y)Na₂B₄O₇–yM_aO_b (where M_aO_b = PbO, Bi₂O₃ and TeO₂) (y = 0.25, 0.5, 0.67 and 0.79) have been investigated. Sound velocities (longitudinal and shear) have been measured at 10 MHz frequency using quartz transducers. Density increases with increase of y and the molar volume decreases. Sound velocities also decrease with increasing y till y ≈ 0.66 above which it increases slightly. Steeper decrease in velocities has been observed in TeO₂ containing glasses. Elastic moduli, Poisson’s ratio and Debye temperature have been calculated. Glass transition temperatures have also been determined and it decreases with increase of y. T_g also exhibits a dependence on the cationic charge in M_aO_b. Infrared spectra of the glasses reveal that the strong network consisting of diborate units is affected only by PbO and only very marginally by Bi₂O₃ and TeO₂. Only glasses with high concentrations of Bi₂O₃ and TeO₂ reveal the presence of mixed bridges such as Bi–O–B and Te–O–B. Consistent with the IR spectral observations, the N₄ values of ¹¹B MAS-NMR remain close to the ideal value of 0.5 of the diborate composition in most of the glasses. A structural model based on the observation that the diborate network is unaffected by Bi₂O₃ and TeO₂ where as PbO opens up and breaks the diborate units is shown to be consistent with all of the experimental observations including mechanical properties.     

Influence of TiO2 on proton conductivity in fuel cell electrolytes based on sol–gel derived P2O5–SiO2 glasses

P₂O₅–TiO₂–SiO₂ based glasses have been prepared by a sol–gel process. The glasses were characterized by structural, thermal, nitrogen adsorption–desorption and conductivity measurements. The structural formation has been confirmed by the FTIR and NMR analysis. The proton conductivity of the glasses increased linearly with increase in temperature. Glasses with an average pore size less than 2 nm showed higher values of proton conductivity in humid atmosphere. The conductivity value increased from 6.47 × 10⁻⁴ S/cm to 3.04 × 10⁻² S/cm at 70% RH in the temperature range 30–90 °C. We observed in fuel cell measurements that the performance of the E1 electrode is superior to that of the other electrodes at the same operating condition. The power density shows a similar pattern to current density.