Barium Tellurite Glasses Research Articles

Effect of La2O3 on the optical, thermal, structural and radiation shielding properties of TeO2–ZnO–BaO glasses

Influence of lanthanum oxide (La2O3) on various properties of melt quenched zinc barium tellurite glasses (TeO2–BaO–ZnO) have been investigated. Lanthanum was limited to 10 mol% beyond which the glass formation ability was affected leading to crystallization in the proposed tie-line. Glass transition temperature improved with lanthanum oxide incorporation, while the density and energy band gap values showed a minimum at 5 mol%. The observed variation with lanthanum oxide doping was clearly elucidated from Raman spectral data, which indicated their influence in modifying the host ternary glass network. Radiation shielding parameter calculations showed a larger mass and linear attenuation coefficients for glasses doped with 10 mol% lanthanum oxide, indicating the influence of heavier oxides in improving the shielding properties and consequently acting as replacement candidate for toxic lead-based compounds.

Physical, optical, and ionizing radiation shielding properties for barium–tellurite glass with different oxides: An experimental study

This study used the melt–quench technique to fabricate four glass systems based on barium–tellurite oxide (BaO–TeO2) glass. The BaO–TeO2 glass system was enhanced with metal oxides such as tungsten oxide (WO3), yttrium oxide, strontium oxide, and lithium oxide. We studied the effects of these oxides as additives experimentally, focusing on their physical, optical, and radiation shielding properties. The fabricated glass density was 4.779–5.372 g/cm3 when different oxides were added. The physical properties of WO3 indicated its superiority over other glasses, supported by the optical properties. We calculated the experimental mass attenuation coefficient for each synthesized sample and compared it to the XCOM software results to assess the radiation shielding efficacy. The difference between the two sets of results ranged from 0.1% to 9.7% for all samples. Furthermore, we calculated the linear attenuation coefficient for each sample, allowing us to determine several properties, such as the effective atomic number, half-value layer, radiation-protection efficiency, mean free path, and transmission factor. According to the gamma radiation shielding results, the sample with WO3 had the best shielding properties, making it a good candidate for radiation shielding applications.

Thermal, structural, optical, and photon shielding studies of cerium-doped barium tellurite glasses.

A series of tellurite-based glasses are prepared by using a melt-quenching method. The effect of cerium on the physical, thermal, structural, optical, spectroscopic, and shielding properties of barium tellurite glass samples is studied. It has been observed that the thermal stability factor increases with increasing cerium ion (Ce3+ ) concentration. The density and other physical parameters such as ion concentration and molar volume are calculated using the Archimedes principle. An increase in optical band gap and density suggests a decrement in non-bridging oxygens. These results are in accordance with Raman results. The blue emission in prepared glasses is studied in terms of International Commissionon Illumination chromaticity coordinates. Moreover, various shielding properties such as mass attenuation coefficient, linear attenuation coefficient, effective atomic number, half-value layer, and tenth-value layer have also been determined to understand the photon shielding characteristics of as-prepared glass samples.

Analysis of radiation shielding, physical and optical qualities of various rare earth dopants on barium tellurite glasses: A comparative study

In the present study, the barium tellurite glasses with the compositions of 60TeO2– 20ZnO– 4BaF2-(16-x) BaCO3-xREEs2O3 (Rare Earth Elements) where x = 0, 1, and 2 of Tm2O3, Er2O3, and Ho2O3 in mol% have been studied via MCNPX simulation code in terms of radiation shielding, physical, and optical qualities. Seven various glasses coded as TeZnBB, TeZnBBTm1.0 (Tm1.0), TeZnBBEr1.0 (Er1.0), TeZnBBHo1.0 (Ho1.0), TeZnBBTm2.0 (Tm2.0), TeZnBBEr2.0 (Er2.0), and TeZnBBHo2.0 (Ho2.0) in this work. The radiation shielding features have been derived using BLL. In addition, N, VM, VS, ri, rp, and F are extracted analytically. The optical properties have been obtained using Tauc's Plot, Mott and Davis, and Lorentz –Lorentz equations. Findings show that the addition of various REEs to barium tellurite glasses improves the radiation shielding capacity of the base glass. Furthermore, the physical features of preferred glasses are enhanced remarkably and as a result, a tight glass structure is created. Moreover, M has small values near zero, showing a narrow bandgap in relevant optical glasses. Also, RLoss and ε increase which is owing to the increase in the number of Non-Bridging Oxygens and causes the locking up of the free movement of the electrons in preferred glasses.

Influence of holmium ions on the structural and optical properties of barium tellurite glasses

Barium tellurite glasses doped with holmium ions [60TeO2 + 20ZnO + 4BaF2 + (16-x) BaCO3 + xHo2O3 (0.25 ≥ x ≤ 2)] synthesized using melt quenching technique have been explored for their optical applications. Compositional tuning led to a maxima and minima in their respective optical bandgap (4.079 eV) and refractive index (2.154) values around 0.75 mol%. Green emission corresponding to the 5I8 → 5F4 (5S2) transition was found to be dominant in the visible region, with a reduction in intensity beyond 0.75 mol.%. This indicated the occurrence of concentration quenching effects and the limit of doping for obtaining high emission intensities. On exposure to nanosecond pulses of 532 nm wavelength, all samples showed good optical non-linearity when investigated using Z-scan technique. Open aperture scans showed reverse saturable absorption behavior owing to two photon absorption process. With reduced limiting threshold values, all compositions in this glass tie-line were found to act as good optical limiters, leading to the possibility of forming efficient limiting devices.

Structural, luminescence and nonlinear optical properties of erbium doped barium tellurite glasses for photonic applications

Structural, luminescence and nonlinear optical properties of erbium doped barium tellurite glasses for photonic applications

Gamma, neutron, and charged particles shielding features and structural properties for barium tellurite glass modified by various oxides

Gamma, neutron, and charged particles shielding features and structural properties for barium tellurite glass modified by various oxides

Thulium-doped barium tellurite glasses: structural, thermal, linear, and non-linear optical investigations

Thulium-doped barium tellurite glasses: structural, thermal, linear, and non-linear optical investigations

Effect of rare earth dopants on the radiation shielding properties of barium tellurite glasses

Rare earth doped barium tellurite glasses were synthesised and explored for their radiation shielding applications. All the samples showed good thermal stability with values varying between 101 °C and 135 °C based on dopants. Structural properties showed the dominance of matrix elements compared to rare earth dopants in forming the bridging and non-bridging atoms in the network. Bandgap values varied between 3.30 and 4.05 eV which was found to be monotonic with respective rare earth dopants indicating their modification effect in the network. Various radiation shielding parameters like linear attenuation coefficient, mean free path and half value layer were calculated and each showed the effect of doping. For all samples, LAC values decreased with increase in energy and is attributed to photoelectric mechanism. Thulium doped glasses showed the highest value of 1.18 cm−1 at 0.245 MeV for 2 mol.% doping, which decreased in the order of erbium, holmium and the base barium tellurite glass, while half value layer and mean free paths showed an opposite trend with least value for 2 mol.% thulium indicating that thulium doped samples are better attenuators compared to undoped and other rare earth doped samples. Studies indicate an increased level of thulium doping in barium tellurite glasses can lead to efficient shielding materials for high energy radiation.

Thermal and light emission properties of rare earth (Eu3+, Dy3+ and Er3+), alkali (Li+, Na+ and K+) and Al3+-doped barium tellurite and boro-tellurite glasses

Thermal and light emission properties of rare earth (Eu3+, Dy3+ and Er3+), alkali (Li+, Na+ and K+) and Al3+-doped barium tellurite and boro-tellurite glasses

Effect of BaO on lead free zinc barium tellurite glass for radiation shielding materials in nuclear application

In this study, the zinc barium tellurite glasses (ZBaT) synthesized and inspected their radiation defensive mechanism and structural behavior. Glass composition (90-x) TeO2 - 10 ZnO - xBaO, where 25≤ x ≤ 35 (mol%) was prepared using the melt quenching technique and glass-forming pseudo-ternary diagram was discussed. Addition of BaO enhances the polarization in the present glasses there by it increases the bond length hence glass network expands resulting in volume. The mass attenuation coefficient (μm) of ZBaT glasses have been evaluated at various energies via Compton scattering technique. The results found that the μm, effective atomic number and effective electron density decrease with the increase in γ-ray energies which is in a good agreement with theoretical values attained using Geant4 and WinXCOM. At 25 mol% BaO content the glass samples show less mean free path (MFP) which were compared with other standard shield defensive materials. The obtained results reveal that the formation of non-bridging oxygens increased with higher concentration of BaO. The transmission spectra of the prepared glasses displayed optical light transparency thereby demonstrating their efficient role being transparent window when used as radiation defensive material without Pb component proving them as eco-friendly for environment.

Effects of annealing on density, glass transition temperature and structure of tellurite, silicate and borate glasses

Barium tellurite, lead tellurite, molybdenum tellurite, lead silicate and bismuth borate glasses of the compositions: xBaO-(100-x)TeO2 (x = 10, 15 and 20 mol%), xPbO-(100-x)TeO2 (x = 15 and 20 mol%), 25MoO3-75TeO2, xPbO-(100-x)SiO2 (x = 50, 60 and 65 mol%) and 40Bi2O3-60B2O3 were prepared by melt-quenching. The effects of long duration thermal annealing (below the respective glass transition temperature (Tg) values) on the density, thermal properties and the short-range structure of glasses were studied. Density increases on average by about 0.5% to 1% and Tg values show drastic increase in the range of 8 °C-64 °C after annealing. Raman and FTIR studies were performed on glasses before and after annealing, FTIR studies found that bismuth borate glasses show a small but significant increase in the fraction of tetrahedral borons in the borate network with annealing. Raman studies on lead metasilicate glass showed an increase in the concentration of SiO4 units that contain three bridging oxygens. Raman and FTIR spectra of all annealed barium and lead tellurite glasses were indistinguishable from those of the initial samples, however the FTIR spectra of annealed 25MoO3-75TeO2 glass show changes in the relative intensities of the peaks due to MoO vibrations along with the growth and sharpening of low frequency Raman bands, furthermore this glass also showed large differences in its crystallization and melting properties during thermal analysis.

Short-range structure of barium tellurite glasses and its correlation with stress-optic response

The atomic parameters of metal ion-oxygen speciation such as bond-lengths and nearest neighbor distances for Ba-O, Te-O and O-O pairs, co-ordination numbers and bond angle distributions for O-Ba-O, O-Te-O and O-O-O linkages are determined by neutron diffraction and Reverse Monte Carlo simulations on the series of xBaO-(100-x)TeO2 glasses containing 10, 15 and 20 mol% BaO. The glass network depolymerizes and the average Te-O co-ordination number decreases from 3.60 ± 0.02 to 3.48 ± 0.02 with increase in BaO concentration. Te-O bond lengths are in the range: 1.97 ± 0.01–1.92 ± 0.01 Å. Ba2+ is mostly in octahedral coordination and the Ba-O bond lengths are in the range: 2.73 ± 0.01 to 2.76 ± 0.03 Å. Te-O co-ordination number is also determined by Raman spectroscopy and it shows good agreement with the neutron data. The short-range structural properties i.e. metal ion coordination number (Nc) and bond lengths (d) were correlated with the stress-optic response. The bonding characteristic, Br values were determined from the structural data of xBaO-(100-x)TeO2 glasses and were used to predict the stress-induced birefringence properties.

Spectroscopic and structural characterization of zinc barium tellurite glass

The spectroscopic and structural characterization of the glass system (90-x) TeO2–10 ZnO–xBaO, where 25≤ x ≤ 35 (mol%) were prepared with a classic melting method from pure oxides. X-ray diffraction studies were performed in order to confirm the amorphous nature of the samples. The analysis of Fourier transform infrared spectroscopy (FTIR) results show the bonding of the glass samples. The FTIR spectrum of the sample depicts that the glass network is built up of tetragonal TeO2 of D24 symmetry where the Te atom is 4-fold coordinated. The color of these glasses were confirmed by CIE L∗a∗b∗ color coordinate and the brightness (L) were changes from green to red, to dark red as BaO concentration increases. The refractive index increase when barium ion (Ba2+) increase.

Structural, thermal, optical and photo-luminescent properties of barium tellurite glasses doped with rare-earth ions

BaO-TeO2 glasses containing 10 to 20-mol% BaO were studied by X-ray diffraction, density, thermal analysis, UV–visible and Raman spectroscopy. The effects of Eu3+, Dy3+, Er3+ and Nd3+ on the density, thermal, optical absorption and luminescent properties of barium tellurite glasses were studied. The short-range structure of barium tellurite glasses consists of TeO4 trigonal bipyramidal and TeO3 trigonal pyramidal units. TeO co-ordination (NTeO) was determined by Raman studies; it was found that that NTeO decreases with increase in BaO and rare earth oxide concentration. The glass transition temperature is a function of both the average single bond enthalpy and non-bridging oxygen concentration in the glass network. Glasses containing Dy3+ and Eu3+ show strong visible light photoluminescence, and our results show that barium tellurite glasses are suitable hosts for rare earth ion luminescence due to low phonon energies.

Zinc chloride modified electronic transport and relaxation studies in barium-tellurite glasses

The ac conductivity of halide based tellurium glasses having composition 70 TeO2-(30-x) BaO-x ZnCl2; x = 5, 10, 15, 20 and 25 has been investigated in the frequency range 10-1 Hz to 105Hz and in the temperature range 453 K to 553 K. The frequency and temperature dependent ac conductivity show mixed behaviour with increase in halide content and found to obey Jonscher’s universal power law. The values of dc conductivity, crossover frequency and frequency exponent have been estimated from the fitting of experimental data of ac conductivity with Jonscher’s universal power law. For determining the conduction mechanism in studied glass system, frequency exponent has been analyzed by various theoretical models. In presently studied glasses, the ac conduction takes place via overlapping large polaron tunneling (OLPT). The values of activation energy for dc conduction (W) and the one associated with relaxation process (E R) are found to increase with increase in x up to glass sample with x = 15 and thereafter it decrease with increase in zinc chloride content. DC conduction takes place via variable range hopping (VRH) as proposed by Mott with some modification suggested by Punia et al. The value of real part of modulus (M') is observed to decrease with increase in temperature. The value of stretched exponent (β) obtained from fitting of M'' reveals the presence of non-Debye type of relaxation in presently studied glass samples. Scaling spectra of ac conductivity and values of electric modulus (M' and M'') collapse into a single master curve for all the compositions and temperatures. The values of relaxation energy (E R) for all the studied glass compositions are almost equal to W, suggesting that polarons have to overcome same barrier while relaxing and conducting. The conduction and relaxation processes in the studied glass samples are composition and temperature independent.

Spectroscopic and structural characterization of barium tellurite glass fibers for mid-infrared ultra-broad tunable fiber lasers

To meet the growing demand for mid-infrared tunable fiber lasers, the spectroscopic and structural properties of Tm3+/Ho3+ co-doped barium tellurite glass fibers are systematically evaluated by absorption, Raman, and photoluminescence spectra measurements. The density, molar volume, refractive index, and glass transition temperature are assessed in detail to fully understand their basic physical and thermal properties. Benefitting from the multiple structural sites in a barium tellurite glass system, the maximum doping concentration of Tm2O3 reaches up to 6.0 wt.% without inducing any crystallization or phase separation. Such a high ion concentration is conducive to reducing the fiber length and obtaining an efficient laser output. Furthermore, an intense ~2.0 μm ultra-broad emission with a full width at half maximum (FWHM) of 382 nm is achieved in the Tm3+/Ho3+ co-doped sample upon excitation at 808 nm by properly adjusting Tm3+ concentration and fiber length. The larger emission cross-sections and higher gain coefficients along with excellent thermal stability indicate that this barium tellurite glass could be an attractive gain medium for mid-infrared ultra-broad tunable fiber lasers.

Optical characterization of Tm3+ in a high barium-tellurite glass in absence and presence of Yb3+: Evidence of strong crystal-field effect and efficient Yb3+→Tm3+ energy transfer

Optical properties of Tm3+ are studied in a (high Ba2+, La3+)-tellurite glass in absence and the presence of co-dopant Yb3+. The Tm3+ ion in this host exhibits strong vis–NIR absorption and intense ~1.83μm NIR-emission along with another weak emission at ~1.48μm upon excitation of its 794nm 3H6→3F4 absorption. In the case of the Yb3+-codoped glass, when the glass is excited through the 978nm (2F7/2→2F5/2) absorption transition of Yb3+, its Tm3+ ion shows strong ~1.83μm NIR-emission but no ~1.48μm emission. The same glass, on the other hand, when is excited with a 980nm laser, its Tm3+ ion exhibits a strong 804nm and a relatively weak ~474nm upconversion emissions. Both the results indicate that an efficient phonon assisted energy transfer takes place from Yb3+ to Tm3+ in the case of the co-doped glass. Co-relation of the optical properties of the Tm3+ ion with its calculated optical parameters shows that the ion in this host experiences a strong crystal field.Strong ~1.83μm NIR-emission of the Tm3+ doped glass and its calculated high values of gain cross-section suggest that the glass is prospective for use as 1.75–1.90μm tunable solid state laser-medium; while the observed intense 804nm upconversion emission of the co-doped glass indicates that the material should be useful as a bio-marker.

Strong crystal-field effect and efficient phonon assisted Yb3+→Tm3+ energy transfer in a (Yb3+/Tm3+) co-doped high barium–tellurite glass

Optical properties of Tm3+ are studied in a (high Ba2+, La3+)-tellurite glass in the absence and the presence of co-dopant Yb3+. The Tm3+ ion in this host exhibits strong Vis–NIR absorption and intense NIR-emission at ~1.83µm along with a weak NIR emission at ~1.48µm upon excitation through its 794nm 3H6→3F4 absorption. Co-relation of the optical properties of the ion with its calculated optical parameters shows that the Tm3+ ion in this host, experiences a strong crystal field. In the case of the Yb3+-co-doped glass, when it is excited through the 978nm 2F7/2 →2F5/2 absorption transition of Yb3+, its Tm3+ ion shows strong ~1.83µm NIR-emission but no ~1.48µm emission. Under 980nm laser excitation, however, the Tm3+ ion of the co-doped glass, shows a strong 804nm and a relatively weak ~474nm upconversion emissions along with two other very weak components at ~648 and ~694nm. All these results indicate that an efficient phonon assisted energy transfer occurs from Yb3+ to Tm3+ in the case of the co-doped glass. The results are interpreted in terms of effect of high Ba2+ in the glass-structure and coupling of some phonons of its nonbridging oxygens with the electronic states of the incorporated Tm3+ and Yb3+.Strong ~1.83µm NIR-emission of the Tm3+-glass and its calculated high values of gain cross-section suggest that the glass is prospective for use as 1.75–1.90µm solid state laser medium; while the observed intense 804nm upconversion emission of the co-doped glass indicates that the material should be useful as bio-marker.

ZnCl2 Modified Physical and Optical Properties of Barium Tellurite Glasses

The optical properties of tellurite based glass systems are composition dependent. For this purpose glass samples of the composition 70TeO2-(30–x)BaO-xZnCl2 with x = 5, 10, 15, 20 and 25 have been synthesized by rapid melt quenching technique. Glassy nature has been confirmed by X-ray diffraction pattern. The physical properties like density, molar volume and crystalline volume have been estimated and found that density decreases while the molar volume increases with increase in ZnCl2 content. The glass transition temperature decreases with increase in halide content due to increase in the non-bridging oxygen contribution. Direct allowed optical transitions are favourable in these glasses and the optical band gap energy (Eopt) has been observed to increase with increase in ZnCl2 content. The value of Urbach energy of these glasses shows increasing behaviour with ZnCl2 concentration indicating the breaking of weak bonds into defects. Metallization criterion for these materials shows that these glasses may be potential candidates for non linear applications.