PbO Content Research Articles

Morphology-controlled preparation of lead powders by electrodeposition from different PbO-containing choline chloride-urea deep eutectic solvent

Lead powders with different morphologies, including corals, rods, wires, needles, ferns and dendritic forms, are prepared by electrodeposition onto a stainless steel substrate from different PbO-containing (10–60mM) choline chloride-urea deep eutectic solvent at cell voltage 2.5V and 343K for 2h. The electrochemical behavior of the PbO dissolved in this solvent is investigated with cyclic voltammetry. It is demonstrated that the increasing of PbO concentration makes the reduction potential EPb(II)/Pb shift positively and facilitates the electrodeposition of lead from PbO in the deep eutectic solvent. According to the analysis of the morphological and crystallographic characteristics of lead powders, the predominant origin of the growth layers is turned away from centre type towards the edge and corner types with the increase in PbO concentration. Due to the large number of growth centres at higher PbO concentration, fine and irregular grains are observed on the surface of formed particles which results in the development of primary and secondary branches in dendrites.

Электродные процессы при электрорафинировании свинца в расплаве KCl-PbCl2-PbO

The influence of PbO addition on current efficiency during the electrorefinement of lead in the KCl-PbCl2-PbO melt was investigated. It was shown that with PbO concentration in the KCl-PbCl2 eqiumolar mixture increasing, the current efficiency of lead decreases. Electrode processes mechanism is proposed.

Sodium enrichment on glass surface during heating of heavy-metal-containing glasses under a reductive atmosphere

Sodium enrichment occurs on the surface of the glass that is in contact with the gas phase during the heat treatment of lead-containing glass under a reductive atmosphere. This technique was previously found to promote lead recovery in waste-glass treatment, and may be potentially applied to glasses containing other heavy metal oxides. Thus, the efficiencies of sodium enrichment were compared among glasses with different heavy metal species (PbO, CuO, and ZnO) in the heat-treatment under a CO-containing atmosphere. The sodium enrichment efficiencies in the treatment of the PbO- and CuO-containing glasses were higher than that in the treatment of the ZnO containing glass. This was because the efficiencies were related to the reduction of the heavy metal oxides. The mass ratio of Na to Si on the glass surface increased as the PbO concentration decreased via reduction of PbO. The sodium-rich phase was separated together with a copper-concentrated phase that was generated via the reduction of CuO. However, ZnO in the glass is thermodynamically more difficult to reduce in the CO-containing atmosphere used in the study, resulting in the lower efficiency of the sodium enrichment.

Probing Metal-Bridging Oxygen and Configurational Disorder in Amorphous Lead Silicates: Insights from 17O Solid-State Nuclear Magnetic Resonance

The detailed degree of mixing between framework Si and metal cations and the nature of oxygen that only links metal cations (metal-bridging oxygen) in archetypal metal oxide glasses have been among the unsolved problems in physical chemistry. Binary lead silicate (PbO-SiO2) glass is an ideal model system for exploring the extent of cation disorder and metal-bridging oxygen because of its peculiar glass-forming ability at high PbO concentration. Here we report the first high-resolution 17O solid-state NMR spectra for binary lead silicate glasses with varying composition (near that of orthosilicate, i.e., Pb/Si = 2), where peaks due to metal-bridging oxygen (Pb-O-Pb), as well as Pb-O-Si and Si-O-Si are clearly resolved. The spectra also reveals that the metal-bridging oxygen possesses a greater topological disorder due to structural complexity in Pb coordination environments. Together with a statistical thermodynamic model of oxygen speciation proposed to describe mixing behavior in oxide glasses with any o...

Compositional-dependent europium-doped lead phosphate glasses and their spectroscopic properties

New multicomponent europium-doped lead phosphate based glasses with various PbO:P2O5 molar ratios were prepared and next studied using optical spectroscopy. Based on excitation and luminescence spectra measurements, some spectroscopic parameters like the phonon energy of the glass host and the fluorescence intensity ratio R of the 5D0→7F2 to 5D0→7F1 transition of Eu3+ ions were determined. Luminescence lifetimes (τm) for the 5D0 state of Eu3+ ions were also evaluated. Optical properties of Eu3+ ions have been investigated in lead phosphate based systems, in which PbO:P2O5 molar ratio were changed from 1:5 to 5:1 in glass composition. The value of the phonon energy of the host decreases with increasing PbO concentration. In addition, the spectral lines are shifted toward higher wavelengths. Non-monotonic dependence of fluorescence intensity ratio R (Eu3+) upon PbO:P2O5 content has been observed. Influence of PbO:P2O5 molar ratio on spectroscopic parameters for Eu3+ are presented and discussed.

Effects of existence form and concentration of PbO on the conductivity of choline chloride–urea deep eutectic solvent

The effects of existence form and concentration of lead oxide (PbO) on the conductivity and viscosity of choline chloride (ChCl)-urea deep eutectic solvent (DES) were investigated. The ESI-MS and FT-IR analyses indicated that three-coordinated complexes are presented in the form of {[PbO∙CO(NH2)2]∙Cl−}−. It is deduced that the complex anions are formed through sp3 hybrid orbitals of Pb2+ ion and three sp hybrid orbitals are all filled with lone pair electrons which are donated by Cl−, O2− and O atoms of urea respectively. The raising of temperature leads to the electrical conductivity increases. With PbO concentration, however, the conductivity increases firstly and then decreases. The viscosity has an opposite change trend compared with the conductivity. These experimental phenomena can be explained by the formation of PbO-containing complexes and oligomers.

Characterization of new Sb2O3-based multicomponent heavy metal oxide glasses

New Sb2O3-based multicomponent heavy metal oxide glasses in the Sb2O3–Na2O–WO3–PbO system were prepared using a conventional melt-quenching technique. Glass formation behavior of these glasses and their thermal, physical and structural properties were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS), differential scanning calorimetry (DSC), UV–Vis–NIR spectroscopy and Fourier transform infrared (FTIR) spectroscopy analyses according to the increasing PbO concentration by keeping the Sb2O3/WO3 ratio constant. Thermal analysis of the glasses were realized in terms of glass transition temperature (Tg), crystallization temperature (Tc/Tp), glass stability against crystallization (ΔT), activation energy of the glass transition reaction (Eg) and fragility parameter (m). Density (ρ), molar volume (VM), oxygen molar volume (VO), oxygen packing density (OPD), refractive index, band gap energy (Eg), average cross-link density (nc‾), number of bonds per unit volume (nb) and Poisson’s ratio (μcal) values were calculated for the interpretation of physical and structural properties of the glasses. FTIR spectra of the glasses were evaluated in terms of structural transformations on the glass network.

Effect of the Pb–Te–B–O system glass frits in the front contact paste on the conversion efficiency of crystalline silicon solar cells

In the present paper, many monocrystal silicon (Si) solar cells are produced by screen printing a front contact paste prepared with crystalline silver particles, a series of glass frits with the different lead oxide (PbO) contents in Pb–Te–B–O system glass, and an organic medium. Under scanning electron microscopy, the selective etching of cells screen-printed by pastes containing the glass frits of different PbO contents from low to high (37.2–52.5 mol%) reveals the corrosion degree of antireflection coating and the growth of silver crystallite microstructures on Si substrate. When the PbO content is 42.7 mol% in glass frits, the silver crystallites of optimal size were formed to make the conversion efficiency of cells best. By comparing the cross-section microstructures of solar cells, the different transition temperatures (Tg = 283–546 °C) of glass frits are found to have a substantial impact on wetting behavior during the firing cycle. When the glass Tg is medium (Tg = 393 °C), the optimal glass layer will be obtained to derive photoelectrons smoothly.

In-situ SIMS uraninite U–Pb dating and genesis of the Xianshi granite-hosted uranium deposit, South China

The southeastern part of the Nanling metallogenic province, China is host to numerous granite-hosted vein-type hydrothermal uranium deposits. The geology and geochemistry of these deposits have been extensively studied. However, accurate and precise ages for the uranium mineralization are scarce because the uranium minerals in these deposits are usually fine grained, and may have formed in several stages. Therefore, the ages previously obtained by the bulk dating techniques are possibly a mixed age.The Xianshi uranium deposit, located in the southeastern part of the Guidong granite complex, is a major uranium deposit in South China. The uranium mineralization from this deposit is mainly fine grained uraninite in quartz or calcite veins which are spatially associated with the Cretaceous mantle-derived mafic dykes. Micro-Raman spectroscopy and X-ray diffraction analyses indicate that the dominant uranium mineral occurs as a rare form of uraninite (U3O7). Three distinct generations of uranium minerals have been identified based on petrographic and field relations. Stage 1 uraninite has the lowest UO2 and highest PbO contents whereas Stage 3 uraninite has the highest UO2 and lowest PbO contents.Uraninite from the Xianshi deposit was dated using an in-situ SIMS U–Pb dating technique. The results show three distinct age groups: 135±4Ma, 113±2Ma and 104±2Ma, which are in excellent agreement with the ages of three episodes of mantle-derived mafic dykes. Therefore, the Xianshi uranium deposit has experienced at least three hydrothermal events that are responsible for the deposition of uranium ores, which are genetically related to the emplacement of three sets of mafic dykes.

Structural correlations in BaO–PbO–B2O3 glasses as inferred from FTIR spectra

Infrared spectra of xBaO·(30-x)PbO·70B2O3, xBaO·(40-x)PbO·60B2O3 and xBaO·(50-x)PbO·50B2O3 glasses have been quantitatively analyzed. The fraction of four coordinated boron atoms varies linearly, for each group, between the values of the corresponding binary borate glasses. The data could be used to calculate and follow the composition dependence of the concentration of structural units in all glasses. The results show a linear increase in the ratio of PbO forming BO4 units to the total content of PbO, with increasing B2O3 in binary PbO–B2O3 glasses. Similar behavior has been observed for the ratio of BaO forming BO4 units to the total content of BaO in binary BaO–B2O3 glasses. The ratio of PbO forming PbO4 units to the total PbO content, and that of BaO forming asymmetric BO3 units to the total BaO content, shows a reversed dependence. The linear change in fraction of four coordinated boron atoms and in density and molar volume suggests that the studied glasses can be treated as mixtures of binary PbO–B2O3 and BaO–B2O3 matrices.

U-Pb zircon and CHIME monazite dating of granitoids and high-grade metamorphic rocks from the Eastern and Peninsular Thailand — A new report of Early Paleozoic granite

Abstract In order to understand the age and tectonic framework of Eastern to Peninsular Thailand from the viewpoint of basement (metamorphic and plutonic) geology, the LA-ICP-MS U-Pb zircon dating and the chemical Th–U-total Pb isochron method (CHIME) monazite dating were performed in the Khao Chao, Hub-Kapong to Pran Buri, and Khanom areas in Eastern to Peninsular Thailand. The LA-ICP-MS U-Pb zircon dating of the garnet-hornblende gneiss from the Khao Chao area gave 229 ± 3 Ma representing the crystallization age of the gabbro, and that of the garnet-biotite gneisses gave 193 ± 4 Ma representing the timing of an upper amphibolite facies metamorphism. The CHIME monazite dating of pelitic gneiss from the Khao Chao gneiss gave scattered result of 68 ± 22 Ma, due to low PbO content and rejuvenation of older monazite grains during another metamorphism in the Late Cretaceous to Tertiary time. The U-Pb ages of zircon from the Hua Hin gneissic granite in the Hub-Kapong to Pran Buri area scatter from 250 Ma to 170 Ma on the concordia. Granite crystallization was at 219 ± 2 Ma, followed by the sillimanite-grade regional metamorphism at 185 ± 2 Ma. Monazite in the pelitic gneiss from this area also preserves Early to Middle Jurassic metamorphism and rejuvenation by later contact metamorphism by non-foliated granite or by another fluid infiltration event in the Late Cretaceous to Tertiary time. The Khao Dat Fa granite from the Khanom area of Peninsular Thailand gave a U-Pb zircon age of 477 ± 7 Ma. This is the second oldest granite pluton ever reported from Thailand, and is a clear evidence for the Sibumasu block having a crystalline basement that was formed during the Pan-African Orogeny. The Khao Pret granite gives U-Pb zircon concordia age of 67.5 ± 1.3 Ma, which represents the timing of zircon crystallization from the granitic melt and accompanied sillimanite-grade contact metamorphism against surrounding metapelites and gneisses. Metamorphic rocks in the Doi Inthanon area also share the similar plutono-metamorphic history with the Khanom and the Hub-Kapong to Pran Buri areas. This suggests that these three areas belong to the Sibumasu block, and the Sibumasu block records similar plutono-metamorphic history from Northern to Peninsular Thailand. Relative abundance of oceanic components in the Khao Chao gneiss, their Late Triassic magmatic ages, and the Early Jurassic metamorphic ages prefer the interpretation that the Khao Chao gneiss belongs to the Sukhothai Arc.

Study of rigidity of semiconducting vanadate glasses and its importance in use of coatings

The elastic moduli of some multicomponent vanadate based glasses were analysed in terms of the bond compression model by some physical parameters such as, the density, average stretching force constant and average atomic ring size. These parameters were calculated for all the glass series and for all the glass composition to estimate the rigidity of these glasses. The results showed that the average force constant and the elastic moduli of these glasses are sensitive to the decrease in PbO content. This behaviour was attributed to the increase in the molar volume and the role of different modifiers. These parameters along with the coordination number of the glasses affect the glass transition temperature. The correlation between the elastic moduli and thermal properties of these samples showed that 0·25MoO3–0.25PbO–0·5V2O5 glass is the most rigid and has an applicable glass transition temperature for coating.

Archaeometric characterization of 17th-century tin-glazed Anabaptist (Hutterite) faience artefacts from North-East-Hungary

The paper presents the first results of a long-term project aiming to reconstruct the production technology of the Anabaptist (Hutterite) tin-glazed ceramics produced in Eastern-Central Europe. Microanalytical investigations were performed on 17th-century faience artefacts (six samples) excavated at Sárospatak, North-East-Hungary. The results are compared with analytical data on the direct or indirect precursor, Italian maiolica.The studied Hutterite faience artefacts reveal similarities with Italian maiolica. Calcareous clay with 14–22 wt% CaO was used for the buff-coloured ceramic body. Up to about 400 μm thick, tin-opacified white and blue lead-alkali glaze was applied on the biscuit-fired body. The glaze suspension contained sand admixture and a significant amount of common salt and was not fritted before application. The colorants used for the ceramic colours are lead antimonate for yellow, cobalt with arsenic, nickel and iron for blue, copper for green and manganese with minor iron for black. The ceramic colours were applied on the unfired glaze and maturing occurred during the second firing. The main technological difference when compared with the Italian Renaissance maiolica is the deliberate use of a high amount of tin oxide (17–20 wt% SnO2) together with 18–28 wt% PbO content for white glaze of the studied Hutterite faience.

On the role of the network modifier PbO in Sm3+-doped borate glasses

A series of Sm3+-doped lead borate glasses with a lead oxide (PbO) content varying from 20mol% to 80mol% and a samarium oxide (Sm2O3) content of 1mol% is investigated. In addition to the network changes in the glass structure, the lead doping has a significant influence on the fluorescence properties of Sm3+ and on the tuneable intrinsic fluorescence of Pb2+ itself. The Pb2+ excitation band shifts monotonously to lower energies; its intensity is significantly reduced for a PbO content of 50mol% and more. For a concentration of 30mol%, the Pb2+ emission overlaps with the intense 6H5/2 to 6P5/2 Sm3+ excitation band enabling for radiative and non-radiative energy transfers. Lifetime measurements of excited Sm3+ show in all cases non-single exponential decay and were fitted by the Inokuti–Hirayama model indicating non-radiative dipole–dipole interaction between neighbouring Sm3+ ions.

Effect of excess PbO on the microstructures and electric field induced strain of Pb0.97La0.02(Zr0.63Sn0.26Ti0.11)O3 antiferroelectric ceramics

Microstructures and electrical properties of ( Pb 0.97 La 0.02)( Zr 0.63 Sn 0.26 Ti 0.11) O 3 (PLZST) antiferroelectric (AFE) ceramics with different PbO content were investigated in this study. X-ray diffraction analysis showed that with the increase of PbO amount, the stability of AFE phase reduced due to the decrease of lead vacancies. Besides, it was observed that the sintering properties could be improved by adding a small amount of PbO . Further, the electric field induced polarization and strain first increased, and then decreased with increasing PbO addition and they showed good frequency stability at low frequency. The maximum strain of 0.65% was obtained in the specimens with 8 mol% PbO content at the frequency 1 Hz. Both a high strain level and relatively good frequency stability in this composition can make a potential candidate for actuators applications over a wide-frequency working range.

Relation between Surface Oxide and SCC of Alloy 600

Stress corrosion cracking (SCC) is one of major threats against the integrity of the structural materials composing a nuclear power plant (NPP). Lead is deleterious element accelerating the SCC of Alloy 600 used as a steam generator tubing material in an NPP. In the present work, the oxide property grown on an Alloy 600 surface was evaluated as a function of PbO content using electrochemical impedance spectroscopy (EIS) and a field-emission transmission electron microscopy, equipped with an energy dispersive X-ray spectroscopy (TEM –EDS) for the specimen prepared using a focused ion beam (FIB). Alloy 600 was immersed in 0.1M NaOH containing PbO in the range of 0-5,000 ppm at 315oC for 2 weeks. The oxide property was compared with SCC susceptibility obtained from a slow strain rate tension (SSRT) test for Alloy 600 in 0.1M NaOH containing PbO. The impedance value was greatly decreased by adding PbO into the solution indicating a decrease in passivity. The composition of the oxide was also changed by Pb in an aqueous solution. The duplex oxide layer consisting of outer porous nickel-rich oxide and inner dense chromium-rich oxide is modified to a Pb incorporated nickel-rich oxide layer. Modification of the oxide property induced by lead incorporation caused an obvious increase in SCC susceptibility. It is expected that lead observed at the crack tip of an early cracked pulled Alloy 600TT tube was considerably responsible for SCC acceleration of this tube among numerous sound tubes in an NPP. Keywords: Alloy 600, impedance, passive oxide, PbO, steam generator, stress corrosion cracking.

The Electrodeposition of Lead in LiCl-KCl-PbCl2 and LiCl-KCl-PbCl2-PbO Melts

The mechanism for the electrode process that occurs on a molybdenum substrate in LiCl-KCl-PbCl2 and LiCl-KCl-PbCl2-PbO melts depending on the concentration of PbO was investigated over the temperature range of 723–823 K using stationary polarization curves and voltammetry techniques. An increase in the concentration of PbO was found to decrease the diffusion-limiting current density for the recovery of lead, which was identified by the appearance of an additional peak in the voltammograms; it can be explained by a decrease in the concentration of Pb2+ ions decrease due to the formation of Pb2O2+ complex ions in the electrolyte. The evaluation of the equilibrium constant KE and the rate constant of the reaction suggests that this reaction is strongly shifted toward the formation of the Pb2O2+ complex ions. A theoretical polarization curve for the diffusion kinetics was calculated.

Chemical durability and structural analysis of PbO–B2O3 glasses and testing for simulated radioactive wastes

Lead borate based glass formulations with high chemical durability and lower melting temperatures compared to the currently used glasses were developed as candidates for the vitrification of radioactive waste. Properties including chemical durability, glass transformation temperature, and melting temperature were analyzed. The chemical durability of PbO–B2O3 glasses with PbO contents ranging from 30 to 80mol% was determined. An average dissolution rate of 0.2gm−2day−1 was obtained for the composition 80PbO⋅20B2O3. These glasses were studied under simulation conditions and showed good potential as a vitrification matrix for radioactive waste management. Clear vitrified waste products containing up to 30mol% SrO and 25mol% Cs2O could be obtained. Leaching rates are about hundred times higher in low PbO glasses compared to high PbO glasses. These results are encouraging since they open up new horizons in the development of low melting temperature lead borate glass for waste immobilization applications.

Dielectric relaxation and optical properties of polyvinyl chloride/lead monoxide nanocomposites

Sol–gel synthesized lead monoxide (PbO) nanoparticles were mixed with polyvinyl chloride (PVC). The dielectric characteristics of PVC/PbO nancomposite films were studied in the temperature range 303–408 K and frequency range 30 kHz–3 MHz. There is a sharp increase in the dielectric constant (e′), after the glass transition temperature. According to the temperature and frequency dependence of the dielectric loss modulus (M″), the observed αa-relaxation peak is due to the micro-Brownian motion of the polymer main chains. The behavior of σac (f) for the composite films indicate that the homogenous distribution of PbO nanoparticles allows the formation of conductive three-dimensional networks throughout the nanocomposite films which assisting the charge carriers to hop from conducting clusters to neighbors. The influences of PbO content on the direct optical band gap and the refractive index of the films are also discussed and compared with those of previous studies of PVC composites. POLYM. COMPOS., 34:2031–2039, 2013. © 2013 Society of Plastics Engineers

Structure–property correlations in lead silicate glasses and crystalline phases

Lead silicate glasses containing 40–65 mol% of PbO were prepared at two melt-quenching rates and characterized by X-ray diffraction, UV-Visible absorption spectroscopy, density, microhardness, thermo-mechanical analysis, differential scanning calorimetry and Raman scattering studies. On increasing the PbO concentration, density increases, glass transition temperature decreases and the optical absorption edge shifts towards longer wavelength. An intense optical absorption band was observed just below the absorption edge in glasses with 55 mol% and higher concentration of PbO. Dilatometric measurements show an unusual property that glasses do not show any abrupt increase in volume near the glass transition temperature but transform directly into the liquid state. Raman spectroscopy confirmed that the concentration of SiO4 tetrahedra containing one or more NBOs increase with PbO mol%. Devitrification studies on lead silicate glasses found that samples with 40–45 mol% of PbO do not crystallize, whereas samples with higher PbO concentration produce multiple crystalline phases like PbSiO3, Pb33Si24O81, Pb2SiO4 and Pb3Si2O7 on heat treatment.