Influence of the composition of high-lead phosphate glasses on the location of the UV transmission edge and technological quality

This paper reports on the results of an investigation into the influence of the purity of the initial materials used for preparing vitreous lead metaphosphate, the acidity of the phosphate matrix, and the contents of additives of Group I–III and V elements and the second glass-former on the location of the UV transmission edge of simple binary and ternary lead phosphate glasses. It is shown that, even for a binary glass of the composition (mol %) 50PbO · 50P₂O₅, the location of the UV transmission edge can be shifted by ～50 nm on the wavelength scale depending on the purity of the initial reactants. The shift of the UV transmission edge toward the UV spectral range for ternary glasses containing no variable-valence elements other than lead is considerably larger than that for the high-lead phosphate glass of the previously proposed composition involving antimony, niobium, and cerium oxides. It is established that the addition of niobium oxide Nb₂O₅ to lead phosphate glasses brings about a red shift of the UV transmission edge and a change in the crystallization ability of the glasses. Niobium oxide at a content up to 1.5 mol % increases the crystallization ability of the glass, whereas a change in the niobium oxide content from 1.5 to 3.1 mol % results in a decrease in the crystallization ability. It is demonstrated that the crystallization ability of high-lead phosphate glasses increases at a boron oxide content higher than 5 mol %.     

Integration Between Optical and Structural Behavior of Heavy Metal Oxide Glasses Doped with Multiple Glass Formers

Heavy metal oxide glasses (composition 60 PbO, 20 Bi₂O₃ mol%) and containing 20 mol% conventional glass formers SiO₂, B₂O₃, and P₂O₅ were prepared. Combined optical and Fourier transform infrared absorption spectra were measured for the prepared glasses to justify the role of glass formers in the optical spectra together with the network structural groups in such glasses. Also, the density and molar volume values were calculated to obtain some insight on the compactness and arrangement in the network. Optical measurements have been used to determine the optical band gap (E_g), Urbach energy (ΔE) and the refractive index (n). Optical spectra of all the samples reveal strong UV absorption which is related to the presence of unavoidable trace iron impurities (Fe ³⁺ ions) contaminated within the raw materials which were used for the preparation of the studied glasses. Additional near visible bands are observed in all prepared glasses due to characteristic absorption of Pb ²⁺ and Bi ³⁺ ions. Furthermore, The variations of the luminescence intensity, values of the optical band gap, band tail, and refractive index can be understood and related in terms of the structural changes that take place in the glass samples. The infrared absorption spectra of the prepared glasses show characteristic absorption bands related to the borate or silicate or phosphate network (BO₃, BO₄, SiO₄, PO₄ groups) together with vibrational modes due to Bi-O and Pb-O groups.     

Thermal properties of ecological phosphate and silicate glasses

The present work deals with ecological phosphate and silicate glasses that belong to the oxide systems: Li₂O-MgO-P₂O₅, Li₂O-CaO-P₂O₅, Li₂O-MgO-P₂O₅-Fe₂O₃; Li₂O-CaO-P₂O₅-Fe₂O₃ and SiO₂-R₂O-R′O (R = Na, K; R′ = Mg, Ca), the last system contains certain amounts of ZrO₂, ZnO, TiO₂. These ecological glasses do not contain toxic substances as BaO, PbO, As₂O₃, As₂O₅, fluorine, CdS, CdSe and they have applications as regards the retention and counteracting action of the harmful compounds resulted from the nuclear plants. The replacement of MgO by CaO leads to an insignificant increasing of the thermal expansion index and a slight decreasing of the characteristic temperatures, except the softening point where the effect is opposite. Adding of iron oxide in the phosphate glass composition causes the increasing of characteristic temperatures and the decreasing of thermal expansion index, both in MgO and CaO-containing phosphate glasses. The ecological silicate glasses are used as opal glasses free of fluorine as well as for lead-free crystal glass (CFP) where BaO and PbO are replaced by non-toxic oxides as K₂O, MgO, ZrO₂, and TiO₂. The paper presents different glass compositions and the technological parameters to prepare the ecological glass samples. Both ecological phosphate and silicate glasses have been characterized as regards the characteristic temperatures (vitreous transition point, low and high annealing points, softening point) and the thermal expansion coefficient. This study presents the changes of the thermal parameters when CaO replaces MgO in phosphate glass samples and the role of iron oxide in the vitreous network. In the case of silicate glasses, the viscosity and wetting angle dependency of temperature are presented. The elemental analysis of the ecological glasses was made by XPS (X-ray photoelectron spectroscopy) which also put in evidence the iron species from the vitreous network.     

Optical Properties and Effect of Gamma Irradiation on Bismuth Silicate Glasses Containing SrO, BaO or PbO

Optical and FT Infrared spectroscopic measurements have been utilized to investigate and characterize binary bismuth silicate glass together with derived samples by replacements of parts of the Bi₂O₃ by SrO, BaO, or PbO. This study aims to justify and compare the spectral and shielding behavior of the studied glasses containing heavy metal ions towards gamma irradiation. The study also aims to measure or calculate the optical energy band gap of these glasses. The replacements of parts of Bi₂O₃ by SrO, BaO or PbO caused some changes within the optical and infrared absorption spectra due to the different housing positions and physical properties of the respective divalent Sr2+, Ba2+, Pb2+ ions. The stability of both the optical and infrared spectra of the studied bismuth silicate glass and related samples towards gamma irradiation confirm some shielding behavior of the studied glasses and their suitability as radiation shielding candidates.     

Formation and stability of glasses with ultra-optical properties in TiO<Subscript>2</Subscript>–Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–PbO system

To obtain ultra-optical property in glasses, as the basis for photonic applications, the glass forming region of TiO₂–Bi₂O₃–PbO system was investigated and determined by melting series of compositions in the system. The glass-forming boundary region was defined. The best compositions for glass formation were found to be around the eutectic and peritectic regions in the corresponding phase diagram. Generally, stability increased with the addition of TiO₂, acting as a conditional glass former, to a maximum of 15TiO₂ mol %. Replacing PbO with Bi₂O₃ in the glass worsened the stability, due to the increase of heavy cation Bi^3– in the glass structure. Finally, the refractive index and dispersion of some stable glasses were measured, which were as high as 2.435 and 10.2, respectively.     

Effect of bulk and nanoparticle Bi2O3 on attenuation capability of radiation shielding glass

The aim of this study is to examine the effect of Bi₂O₃ concentration and particle size on Bi₂O₃ glass. The tested glasses had the composition of SiO₂–Bi₂O₃–CaO–MgO–B₂O₃–K₂O–Na₂O–ZnO. Ordinary glass was compared with glasses with 10% Bulk Bi₂O₃, 10% Bi₂O₃ Nanoparticles (NPs), 20% Bulk Bi₂O₃, and 20% Bi₂O₃ nanoparticles. The mass attenuation coefficients (MACs) of all the investigated glasses were determined between 0.0595 MeV and 1.41 MeV. The results demonstrated that increasing the Bi₂O₃ content in the glass matrix improved their shielding capability, as well as showing that the NPs provided greater attenuation than the bulk Bi₂O₃ at the same concentration. The percent increase in the MAC between the bulk and nano Bi₂O₃ was also calculated and analyzed. From the MAC values, the LAC of the glass was determined and similar results were found compared to the MAC figure. The HVL and MFP of the glass were then analyzed and the results demonstrated that the glass with Bi₂O₃ NPs attenuated the same amount of photons at a smaller thickness, making the NP shield more effective. The heaviness of the samples illustrated that all the tested samples have a smaller weight than pure lead, making them more desirable. The attenuation factor of the glass (Att. Factor %) showed that increasing the Bi₂O₃ content in the samples and increasing the thickness of the shields both improve the shielding capability of the glass. Lastly, the d_lead of the glasses was determined, indicating that the greatest reduction in thickness occurs near the K-absorption edge of bismuth. Overall, the glass with 20% Bi₂O₃ NPs demonstrated to have the greatest potential for radiation shielding applications.     

Influence of rare earth additives and boron component on electrical conductivity of sodium rare earth borate glasses

Sodium rare earth borate glasses (Na₂O)_35.7(RE₂O₃)_7.2(B₂O₃)_57.1 (RE = Sm, Gd, Dy, Ho, Y, Er, and Yb), were prepared from a mixture of Na₂CO₃, RE₂O₃ and B₂O₃, and their properties as an Na⁺ ionic conductor were investigated. Density increased with increasing atomic weight of RE. Crystallization temperature and crystal melting temperature of the present borate system was lower than that of the previously reported silicate and germanate system. Results of the ¹¹B NMR measurement suggested that half of all boron atoms are coordinated by four oxide ions to give a [BO₄] tetrahedral unit and the others are coordinated by three oxide ions to give a [BO₃] planar triangular unit. The electrical conductivity slightly decreased with increasing the ionic radius of RE³⁺. (Na₂O)_35.7(Y₂O₃)_7.2(B₂O₃)_57.1 glass exhibited the electrical conductivity which is about one order of magnitude lower than those of the previously reported (Na₂O)_35.7(Y₂O₃)_7.2(SiO₂)_57.1 and (Na₂O)_35.7(Y₂O₃)_7.2(GeO₂)_57.1 glasses. It was assumed that this lower electrical conductivity is due to the lower content of Na⁺ ions as conduction species in the former glass, compared with the latter two glasses.     

Synthesis and characterization of clinopyroxene based glasses and glass-ceramics along diopside (CaMgSi2O6)-jadeite (NaAlSi2O6) join

The crystallization behavior and mechanical characterization of glasses based upon the compositions along diopside (CaMgSi₂O₆)-jadeite (NaAlSi₂O₆) join has been investigated. Six glasses were obtained by the melt-quenching technique. Structural and thermal behaviors of these glasses were investigated by density and molar volume, infrared spectroscopy (FTIR) and dilatometry. The crystallization behavior of glasses was investigated by using differential scanning calorimetry (DSC). Sintering and crystallization behavior of the glass-ceramics were investigated under non-isothermal heating conditions up to temperatures of 850 °C. Mechanical characterization of glasses was investigated by using the measurement of Vickers indentation hardness and elastic constants such as Young's modulus (E), shear modulus (G), bulk modulus (K) and Poisson's ratio (ν). These data of the glasses were correlated with the structure of glasses, nature and role played by glass forming cations.     

Effect of Bi2O3 on the electrochemical performance of LaBaCo2O5+δ cathode for intermediate-temperature solid oxide fuel cells

The LaBaCo₂O_5+δ−x wt.% Bi₂O₃ (LBCO-xBi₂O₃, x=10, 20, 30, and 40) were prepared as composite cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) via the conventional mechanical mixing method. The effect of Bi₂O₃ on polarization resistance, overpotential, and long-term stability of the LBCO cathode was investigated. An effective sintering aid for LBCO cathode, Bi₂O₃ not only lowers its sintering temperature by ~200 °C, but also improves the electrochemical performance within the intermediate temperature range of 600–800 °C. Electrochemical impedance spectroscopy measurements showed that the addition of 20 wt% Bi₂O₃ to LBCO exhibited the lowest area-specific resistance of 0.020 Ω cm² at 800 °C in air, which was about a seventh of that of the LBCO cathode at the same condition. At a current density of 0.2 A cm⁻², the cathodic overpotential of LBCO-20Bi₂O₃ was about 12.6 mV at 700 °C, while the corresponding value for LBCO was 51.0 mV. Compared to B₂O₃–Bi₂O₃–PbO frit, the addition of Bi₂O₃ significantly improved the long-term stability of cathode. Therefore, LBCO-20Bi₂O₃ can be a promising cathode for IT-SOFCs.     

Properties, Structure, and Application of Low-Melting Lead–Bismuth Glasses

Glass formation, crystallization, and physicochemical properties, as well as glass structure in the system PbO – ZnO – Bi₂O₃ – B₂O₃ – SiO₂, are investigated in the section with a constant molar content of glass-formers (B₂O₃ + SiO₂) equal to 20%. A nonlinear dependence of glass properties on their composition is established caused by the change of the coordination state of lead ion in glass structure. The developed glasses are recommended for joint and seals in the production of a new generation of physical parameter sensors.     

Piezoelectric and dielectric properties of (Bi0.5Na0.5)0.94Ba0.06TiO3–Ba(Zr0.04Ti0.96)O3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics of (1 − x)(Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃–xBa(Zr_0.04Ti_0.96)O₃ (abbreviated as BNBT–BZT100x, wherein x from 0 to 10 mol%) were fabricated. We have studied effects of amount of BZT content on the electrical properties and microstructures. X-ray diffraction analysis indicates that a solid solution is formed when BZT diffuses into the BNBT lattice, and further the crystal structure of sintered hybrid changes from rhombohedral to tetragonal symmetry along with increasing BZT content. Piezoelectric property measurements reveal that the BNBT–BZT4 ceramics has the highest piezoelectric performance, for example, the piezoelectric constant d₃₃ reaches to 167 pC/N and planar electromechanical coupling factor k_p is up to 0.27. In addition, the effect of Bi₂O₃ on the electrical properties and microstructure of the BNBT–BZT4 ceramics have also been studied, and found that the doping of Bi enhances the piezoelectric properties of ceramics.     

Gallium (III) oxide reinforced novel heavy metal oxide (HMO) glasses: A focusing study on synthesis,optical and gamma-ray shielding properties

In this study, three heavy metal oxide glasses (A:46.0PbO-42.0Bi₂O₃-12.0Ga₂O_3, B:45.94PbO-42.66Bi₂O₃-10.0Ga₂O₃-1.4BaO, C:72.8PbO-17.0GeO₂-10.2Ga₂O₃) were synthesized to determine their optical and gamma-ray shielding properties in terms of assessing their potential applications in medical and industrial radiation facilities. Glasses were synthesized using melt quenching method. The optical band gap energy is calculated by the absorption spectrum measured at room temperature. We found a large band at 500 nm that refers to Bi+ions and appears to samples A and B that contain Bi₂O₃ in their compositions. Optical band gap energies were reported as 2.014 ev, 2.055 eV and 2.430 eV for A, B and C samples, respectively. Next, fundamental gamma-ray parameters were also determined using MCNPX general Monte Carlo code and Phy-X/PSD in 0.15–15 MeV photon energy. Our findings clearly showed that the B sample, which includes the highest concentration of Bi₂O₃, has a considerable advantage in terms of gamma-ray attenuation. Moreover, the results also showed that sample B has significantly higher attenuation properties than shielding concretes and several glass shields. It can be concluded that Bi₂O₃ is a useful component for heavy metal oxide glasses in terms of improving gamma-ray shielding capabilities for radiation shielding applications.     

Thermoelectric properties of Bi2O3-added WO3 ceramics

Tungsten trioxide (WO₃) ceramics were prepared by firing Bi₂O₃-added WO₃ compacts with atomic ratios of Bi/W?=?0.00, 0.01, 0.03, or 0.05, in which Bi₂O₃ was mixed as a sintering agent. Dense ceramics consisting of remarkably grown WO₃ grains were obtained for Bi-containing samples with Bi/W?=?0.01, 0.03, and 0.05. The grain growth was enhanced by the liquid phase of Bi₂W₂O₉ formed among the WO₃ grains while firing. The XRD patterns did not show evidence for Bi inclusion into the WO₃ lattice, but the SEM-EDX showed an intensive distribution of Bi into the grain boundaries. Electrical conductivity σ and Seebeck coefficient S were measured in a temperature range of 373–1073?K. The temperature dependences indicated that the Bi₂O₃-added WO₃ ceramics were n-type semiconductors. It was considered that the electron carriers were generated from oxygen vacancies included into the WO₃ grains. The thermoelectric power factors S²σ for the ceramics ranged from 1.5?×?10^?7 W?m^?1 K^?2 to 2.8?×?10^?5 W?m^?1 K^?2, and the highest value occurred at 970?K for the ceramic with Bi/W?=?0.01.     

Fabrication and electrical properties of Pb(Co1/3Nb2/3)O3 ceramics

Pb(Co_1/3Nb_2/3)O₃ (PCN) ceramics have been produced by sintering PCN powders synthesized from lead oxide (PbO) and cobalt niobate (CoNb₂O₆) with an effective method developed for minimizing the level of PbO loss during sintering. Attention has been focused on relationships between sintering conditions, phase formation, density, microstructural development, dielectric and ferroelectric properties of the sintered ceramics. From X-ray diffraction analysis, the optimum sintering temperature for the high purity PCN phase was found at approximately 1050 and 1100 °C. The densities of sintered PCN ceramics increased with increasing sintering temperature. However, it is also observed that at very high temperature the density began to decrease. PCN ceramic sintered at 1050 °C has small grain size with variation in grain shape. There is insignificant change of dielectric properties with sintering temperature. The P–E hysteresis loops observed at −70 °C are of slim-loop type with small remanent polarization values, which confirmed relaxor ferroelectric behavior of PCN ceramics.     

Preparation and elastic moduli of germanate glass containing lead and bismuth

This paper reports the rapid melt quenching technique preparation for the new family of bismuth-lead germanate glass (BPG) systems in the form of (GeO₂)₆₀–(PbO)_40−x–(½Bi₂O₃)_x where x = 0 to 40 mol%. Their densities with respect of Bi₂O₃ concentration were determined using Archimedes’ method with acetone as a floatation medium. The current experimental data are compared with those of bismuth lead borate (B₂O₃)₂₀–(PbO)_80−x–(Bi₂O₃)_x. The elastic properties of BPG were studied using the ultrasonic pulse-echo technique where both longitudinal and transverse sound wave velocities have been measured in each glass samples at a frequency of 15 MHz and at room temperature. Experimental data shows that all the physical parameters of BPG including density and molar volume, both longitudinal and transverse velocities increase linearly with increasing of Bi₂O₃ content in the germanate glass network. Their elastic moduli such as longitudinal, shear and Young’s also increase linearly with addition of Bi₂O₃ but the bulk modulus did not. The Poisson’s ratio and fractal dimensionality are also found to vary linearly with the Bi₂O₃ concentration.     

INFLUENCE OF GLASS COMPOSITION ON REDUCIBILITY OF Ag+, Bi3+, Sb3+, AND PP+*

The reducibility of a number of ions by dry hydrogen was studied in various glass compositions. Reduction temperatures with dry hydrogen were about 75° C, lower than with wet hydrogen. The glasses contained 5.0% of Sb₂O₃, Bi₂O₃, or PbO or 0.1% of Ag₂O. In all of the glasses, silver ions were reduced at lower temperatures as basicity was increased, while an increased ratio of B³⁺ to O^2- or Si⁴⁺ to O^- increased stability. The reducibility of Bi³⁺, Sb³⁺, and Pb²⁺ are not easily interpreted. Silver showed reduction at approximately 130°C., bismuth at 200°C., lead at 350°C., and antimony at 400°C.     

Effect of doping by transitional elements on properties of chalcogenide glasses

In present work, the results on the influence of doping by transitional elements on thermal, optical, structural and magnetic properties of chalcogenide glasses are presented.Thermal properties (T_g values for undoped and doped glasses) were studied using differential scanning calorimetry technique. Activation energy of glass transition was estimated with the use of Kissinger’s expression. Structural studies were carried with the use of Raman and infrared spectroscopy and X-ray diffraction. Radial electron distribution functions in doped and undoped bulk glasses were obtained and analyzed. In Raman spectra, main observed effect under the introduction of dopants was the change of relative concentration of main and non-stoichiometric structural units characteristic for As₂S₃ glasses. Investigation of influence of transition metals Mn-dopants on the optical properties of As₂S₃ glass was studied in mid-IR region. Pure chalcogenide glasses are diamagnetics. Introduction of transitional and rare earth impurities changes the magnetic properties of investigated chalcogenide glasses.     

Vitrification, Properties, and Structure of Lead-Tellurite Borate Glasses

The vitrification, structure, and physicochemical properties of glasses in the PbO – ZnO – B₂O₃ – TeO₂ system are studied. The dual role of the lead ions in the glass structure is confirmed. It is demonstrated that the coordination transition of boron ions correlates with the concentration of PbO in glass. A nonlinear dependence of properties on the glass composition is due to the structural modifications in glass.     

Influences of La and Er on structure and properties of Bi2O3–B2O3 glass

Bi₂O₃·2B₂O₃ glasses doped with La₂O₃ and Er₂O₃ were prepared by the melting-quenching method with AR-grade oxides. IR analysis was used to investigate the glass network structure. The characteristic temperatures including the glass transition temperature (T_g), crystallization temperature (T_p), and melting temperature (T_m) were estimated by DSC. The coefficient of thermal expansion (α), mass density (D), and Vickers hardness (H_v) were also measured. The results show that the basic network structure of Bi₂O₃·2B₂O₃ glasses doped with rare-earth oxides consists of chains composed of [BO₃], [BO₄], and [BiO₆] units. La₂O₃ and Er₂O₃ act as network modifiers. As the doping concentrations of the rare-earth oxides were increased, T_g increased and α decreased, indicating that a more rigid glass was obtained. Er₂O₃ reduces the melting temperature and prevents glass crystallization. La₂O₃ contributes to the improvement of the microhardness of Bi₂O₃·2B₂O₃ glass.     

Effect of A2O3 (A = La,Y, Cr,Al) on thermal and crystallization kinetics of borosilicate glass sealants for solid oxide fuel cells

Influence of various intermediate oxides on thermal, structural and crystallization kinetics of 30BaO–40SiO₂–20B₂O₃–10A₂O₃ (A = Y, La, Al, Cr) glasses has been studied. The highest glass transition temperature (T_g) with high thermal stability is observed in Y₂O₃ containing glasses as compared to other glasses. The thermal expansion coefficient (TEC) increases with increasing heat treatment duration in all the glasses. The maximum increase in TEC is observed in Cr₂O₃ containing glass ceramics. FTIR study showed that transmission bands due to silicate and borate chains become sharper with splitting after heat treatment. A selected glass sample (BaCr) has been tested for interaction and adhesion with Crofer 22 APU interconnect material for its application as a sealant in solid oxide fuel cell.