Pure Lead Research Articles

Vaporization and caloric studies on yellow lead oxide PbO

The vaporization of pure yellow PbO(c) to provide reference data for lead titanate and other lead oxide containing compounds was investigated at temperatures of 810–1040 K. Thermodynamic quantities of sublimation and reaction enthalpies, and entropy were derived from the partial pressures of gaseous Pb, PbO, and O2 over pure yellow lead oxide. The experimental sublimation enthalpy of Pb from PbO(c) was ΔsubH930K0(Pb)=(206±5)kJmol−1, ΔsubH298K0(Pb)=(215±5)kJmol−1 and for PbO was ΔsubH930K0=(223±3)kJmol−1, ΔsubH298K0=(236±3)kJmol−1. The enthalpy, entropy and Gibbs energy of the following reactions were determined by 2nd and 3rd law analysis at T = 930 K:TableΔrHT0 kJ mol−1ΔrST0J mol−1 K−1ΔrGT0 kJ mol−1PbO(c) = PbO(g)223 ± 395 ± 1137 ± 4PbO(c) = Pb(g) + 0.5O2(g)312 ± 6136 ± 1186 ± 5PbO(g) = Pb(g) + 0.5O2(g)86 ± 240 ± 150 ± 2Data base dependent adaptation to 298 K are given in the tables below. Heat capacity measurements under constant pressure (Cp(T)0) by Dynamic Scanning Calorimetry (DSC) in the temperature range 298–1100 K resulted in two complex polynomial equations (see tables). The Cp(T)0 values increased to a maximum at T = about 750 K from (47.6–50.12) J mol−1 K−1 and decreases to 48.4 at the phase transition of Tc = 1006 K. Beyond the transition, Cp(T)0 becomes linear and nearly constant with ≅ 48.5 J mol−1 K−1 at 1100 K. Even the low values of entropy, ∆trsST0 = (0.045 ± 0.001) J mol−1 K−1 and enthalpy, ∆trsHT0 = (0.045 ± 0.002) kJ mol−1, and the peak shape of the phase change in the Cp(T)0 function suggest that the transition can be classified as a first order one. This phase transition was not published so far. The enthalpy and the entropy values were calculated from the Cp(T)0 polynomials and from the vaporization studies.

Lead Whisker Formation in the Gold-Lead System

Metallic whiskers of pure lead (Pb) have been observed in the solder of several types of transistors. The conditions that lead to these whiskers were evaluated, including characterization of the whisker lengths and whisker density as a function of time and temperature. The potential cause and impact they would have on the reliability of electronics has been investigated. Based on these results, it is hypothesized that these whiskers may be caused by the relief of residual stresses that are created during the evolution of Au-In and/or Au-Pb intermetallic compounds or, possibly, by a decomposition of the AuPb3 phase. Due to their small size, the Pb whiskers that were observed were considered to not be a reliability concern, but similar or larger Pb whiskers could cause electrical failure in some applications.

Laser Ablation of Hybrid Perovskite Bulks into Nanoparticles: Adamantylammonium Halides as Ligands and Halide Sources

AbstractAn array of hybrid lead halide CH3NH3Pb(Br/I)3 colloidal perovskites have been successfully synthesized by 532 nm laser irradiation of either pure lead halide CH3NH3PbX3 (X=Br−, I−) or mixed‐halide CH3NH3PbBr3‐xIx bulks, by using 2‐adamantylammonium iodide and/or 2‐adamantylammonium bromide as the source for varying the perovskite halide content as well as for confining the material to the nanoscale.

Studies of Multiferroic Palladium Perovskites

We have studied the atomic force microscopy (AFM), X-ray Bragg reflections, X-ray absorption spectra (XAS) of the Pd L-edge, Scanning electron microscopey (SEM) and Raman spectra, and direct magnetoelectric tensor of Pd-substituted lead titanate and lead zirconate-titanate. A primary aim is to determine the percentage of Pd+4 and Pd+2 substitutional at the Ti-sites (we find that it is almost fully substitutional). The atomic force microscopy data uniquely reveal a surprise: both threefold vertical (polarized out-of-plane) and fourfold in-plane domain vertices. This is discussed in terms of the general rules for Voronoi patterns (Dirichlet tessellations) in two and three dimensions. At high pressures Raman soft modes are observed, as in pure lead titanate, and X-ray diffraction (XRD) indicates a nearly second-order displacive phase transition. However, two or three transitions are involved: First, there are anomalies in c/a ratio and Raman spectra at low pressures (P = 1 − 2 GPa); and second, the c/a ratio reaches unity at ca. P = 10 GPa, where a monoclinic (Mc) but metrically cubic transition occurs from the ambient tetragonal P4 mm structure in pure PbTiO3; whereas the Raman lines (forbidden in the cubic phase) remain until ca. 17 GPa, where a monoclinic-cubic transition is known in lead titanate.

Differential access to metal wealth from colony to capital to collapse at Phoenician and Punic Carthage: non-ferrous alloys and mineral resources from the Bir Massouda site

This article presents the first stratified archaeometric data of the earliest metallurgical assemblage of Maghrebi North Africa from the perspective of the non-ferrous alloys and minerals. From its foundations as a colony to its formation as an imperial power and subsequent decline and collapse, the Carthaginian state maintained a tradition of metallurgical production. Previous research has highlighted workshops of iron and steel manufacture at Bir Massouda and how this facilitated empire formation. The non-ferrous metals and alloys from Bir Massouda also provide information on the shifting fortunes of the Phoenician-Punic commercial endeavor in its geopolitical Mediterranean context. Following its foundation, Carthaginian non-ferrous alloys included the pure copper, tin bronze, and recycled arsenic-tin bronze alloys typical to Iron Age Mediterranean archeological deposits. At its imperial peak, Carthage maintained a relatively high diversity of alloy and mineral types, including pure copper, tin bronze, arsenical copper, leaded tin bronze, leaded arsenical copper, and lead. Two pieces of non-ferrous slag are evidence for bronze recycling. A special cobalt-iron-copper mineral was being processed likely as a colorant for glass or other decorative pigment, and glassy copper-based debris was found adhered to a ceramic or kiln component. During its early clashes with Rome and eventual decline and collapse, the Late Punic metal procurement system was stilted, likely due to restricted access to territorial mines previously held by Carthage in the Iberian Peninsula and Sardinia, with a reversion back to an assemblage of pure copper, arsenical copper, arsenic-tin bronze, and lead.

Radiation shielding features using MCNPX code and mechanical properties of the PbO[sbnd]Na2O[sbnd]B2O3[sbnd]CaO[sbnd]Al2O3[sbnd]SiO2 glass systems

The novel glasses with compositions PbONa2B4O7 CaOAl2O3SiO2 glasses are prepared by the melt quenching technique. The radiation shielding and mechanical properties of the prepared glasses are presented and discussed in details. The mass attenuation coefficient (μ/ρ) which is the basic parameter in the evaluation of the radiation interaction with shielding materials was calculated according to MCNPX code, and the results were compared with those obtained by XCOM program. The simulation results match most of the XCOM data very well. Additionally, the results revealed that both (μ/ρ) and the effective atomic number (Zeff) of the prepared glasses increase with increasing lead monoxide from 0 to 50 mol. %. Also, the difference of HVL values of the prepared glass samples and that for the pure lead decrease when the concentration of lead monoxide increases. It is found that the removal cross-sections, ΣR values for the prepared glasses lie within the range 0.1006–0.1215 cm−1.

Re-interpretation of the Old Masters' practices through optical and rheological investigation: The presence of calcite

Abstract Lead white, composed of a mixture of cerussite and hydrocerussite (respectively PbCO3 and Pb3(CO3)2(OH)2), is often associated in paintings with other white pigments, especially calcite. By combining in-situ analyses with paint reconstructions, we attempt to get a better understanding of the role of this addition of calcite and to investigate how artists may have used it to modify the properties of their paints. Lead-based white pigments of a Dutch 17th-century nuancier have been analysed as well as historical paintings. Two examples are given: one from a painting by Roger van der Weyden, in the 15th century, and one by Nicolas Poussin, in the 17th century, from specific zones that indicate the addition of calcite. The presence of calcite and pigments enhances both the optical and the rheological properties. Visible reflectance spectroscopy was carried out on pure paints as well as mixtures and indicated an increase in the transparency of the paint mixture in comparison to pure lead white. Rheological measurements also indicated an increase in the elastic and viscous moduli, as well as of the yield stress again in comparison to pure lead white. Calcite could thus have been used to assist in the creation of impasto effects in lead white paints.

Electrochemical performance of Pb[sbnd]Co composite anode during Zinc electrowinning

In this study, the electrochemical and anodic behaviors of CoPb anodes in electrowinning process were investigated. Accumulative roll bonding (ARB) method was applied to fabricate CoPb composites. The electrochemical properties of the produced anodes were investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry technique (CV), electrowinning tests, and scanning electron microscopy (SEM). The results indicated that ARB-process is an appropriate method to developed CoPb anodes. The produced anodes containing 0.5% of Cobalt particles as a second phase after 10 cycles of ARB process which is named Pb-0.5%Co-10pass samples showed 83.37% increase in current density compared to pure lead anode. The results of electrowinning tests revealed that Pb-0.5%Co-10pass samples had the best anodic performance with a significant lower corrosion rate, product and electrolyte contamination, slime formation, energy consumption and a higher Zn deposit as a product and energy conservation.

Electronic Properties of {111} Twin Boundaries in a Mixed-Ion Lead Halide Perovskite Solar Absorber

We present first-principles theoretical predictions of the electronic properties of {111} twin boundaries in pure formamidinium lead iodide (FAPI) as well as a mixed-ion lead halide perovskite containing formamidinium, Cs, I, and Br. We find that the {111} twin boundary is extremely stable in pure FAPI but introduces no electron or hole trapping states and presents relatively small barriers (<100 meV) to transport of electrons and holes, suggesting that they are relatively benign for solar cell performance. However, in the mixed-ion perovskite, twin boundaries serve as a nucleation site for formation of an I- and Cs-rich secondary phase. The reduced band gap in this segregated phase leads to hole trapping and is likely to enhance electron–hole recombination and lead to reduced open-circuit voltage in solar cell devices. These results highlight the role of twin defects as nucleation sites for secondary phases, which can be extremely detrimental to solar cell performance.

Not all lightweight lead aprons and thyroid shields are alike

ObjectiveWith the explosion of minimally invasive surgery, the use of fluoroscopy has significantly increased. Concurrently, there has been a demand for lighter weight aprons. The industry answered this call with the development of lightweight aprons. Our goal was to see whether lighter weight garments provide reduced protection. MethodsDry laboratory testing was performed in a standard X-ray room, using a standard fluoroscopy table and standard acrylic blocks. A commercial-grade pressurized ion chamber survey meter (Ludlum Model 9DP; Ludlum Measurements, Inc, Sweetwater, Tex) was used to detect gamma rays and X-rays above 25 keV. Nonlead aprons from several manufacturers were tested for scatter radiation penetration above the table at a fixed distance (3 feet) and compared with two standard 0.5-mm lead aprons of different manufacturers. ResultsScatter measurements were made at 60 kVp and 70 kVp for pure lead (0.5 mm), mixed, and nonlead protective garments. Scatter penetration for the nonlead blends and barium aprons was 292% and 258%, respectively, at 60 kVp compared with the pure lead apron. At the higher beam quality of 70 kVp, the scatter penetration was 214% and 233% for the blend and barium aprons, respectively, compared with the pure lead apron. Our measurements demonstrate a noticeable difference in scatter reduction between pure lead and nonlead garments. Pure barium aprons and nonlead aprons from certain companies demonstrated scatter penetration that is inconsistent with the 0.5 mm of lead equivalence as claimed on the label. In addition, there was an incidental finding of a handful of lightweight aprons with significant tears along the seams, leaving large gaps in protection. Our study also demonstrates that several companies rate their lightweight garments as 0.5 mm lead equivalent, when actually only a small area on the chest and abdomen where the garment overlapped was 0.5 mm, leaving the rest of the garment with half the protection at 0.25 mm. ConclusionsOur reliance on protective lead garments to shield us from the biologic effects of radiation exposure and the inferiority of some lightweight garments necessitate a streamlining of the testing methods and transparency in data reporting by manufacturers.

Sonication-assisted synthesis of a new rod-like metal-organic coordination polymer compound; novel precursor to produce pure phase nano-sized lead(II) oxide

In the current research, a novel metal-organic coordination polymer compound, [Pb(L)(SCN)2]n in which of L represent C4H6N2 (1-methyl imidazole), through methodologies of the branch tube and sonochemical irradiation were fabricated and characterized via elemental analysis such as X-ray, FT-IR and Hirshfeld surface analyses. The obtained results revealed that the same crystalline phase is obtained for every compound, regardless of the type of employed methodology. Single crystal X-ray analyses on compound 1 imply that Pb2+ ions are 8-coordinated. Besides, topological analysis reveals that the compound 1 is 3,4,7 L1 net. Hirshfeld Surface Analysis of compound 1 is also studied. This present study demonstrates that neither the shape nor the morphology is maintained, representing the effect of sonochemistry to modulate both morphology and dimensions of the resultant crystalline materials, independently of whether there exists a 2D coordination polymer. Additionally, the influence of reaction time as well as temperature on the growth and final morphology of structures, obtained by sonochemical irradiation, are studied. Eventually, the calcination of compound 1 in the air atmosphere resulted in production of lead (II) oxide nanoparticles at 700 °C.

Modelling surface melting of macro-crystals and melting of nano-crystals for the case of perfectly wetting liquids in one-component systems using lead as an example

It is known that the majority of crystals melt without superheating. It is because liquids usually perfectly wet their own crystals, leading to surface melting at a lower temperature compared to the bulk melting point of the same crystal. In this paper first this phenomenon is modelled. The equilibrium thickness of the liquid nano-layer is found to approach asymptotically infinity as temperature approaches the bulk melting point of the macro-crystal. Further, the size of the solid crystal is gradually reduced below 100 nm and the size dependence of melting nano-crystals is modelled. Calculations are performed for pure lead (Pb), for which experimental results were published for both of the above mentioned phenomena. The validity of our models is confirmed by these literature experimental results. Co-existence of a core solid and a liquid shell is found in a finite temperature range below the macroscopic melting point in one-component nano-systems, explained by the extended phase rule of Gibbs. The lower temperature of this T-range is called here the solidus temperature, while the upper temperature of this T-range is called here the liquidus temperature of the one-component nano-crystal. Both the solidus and liquidus temperatures of the nano-crystal decrease with decreasing particle size and merge together at a critical particle size (found at 4.7 nm and at 493 K for pure lead with bulk melting point of 600.6 K). Below this critical size the nano-particle melts at a single temperature. A general rule is established claiming that when a one-component macro-crystal melts with surface melting, then the same nano-crystal melts with a solid-liquid co-existence within a finite temperature range and vice versa. Three principle types of binary nanophase diagrams are predicted for each type of macro-phase diagram, depending on whether the two components melt with or without surface melting.

Green lightweight lead-free Gd2O3/epoxy nanocomposites with outstanding X-ray attenuation performance

This work describes the design, preparation, and characterization of an environmentally friendly, clinically safe, and lightweight Gd2O3/epoxy nanocomposite (Gd nanocomposite) that can provide an alternative to traditional toxic lead (Pb)-based materials for diagnostic X-ray protection. Based on the effect of inter-particle forces, the adsorption of sodium dodecyl sulphate (SDS) surfactant on the surface of ultrafine ball milled Gd2O3 reduces the agglomeration and aggregation in nanoparticle preparation and dispersion in the polymer matrix, thereby improving the attenuation properties of this material per unit area. While an 8 mm-thick Gd nanocomposite with volume fractions (ϕs) of 0.10, 0.12, and 0.14 can reduce transmitted X-ray intensity by about 93–99%, a 16 mm composite thickness (ϕs = 0.12) can achieve more than 99% protection in the energy range 60–120 kVp. These specimens show comparable attenuation efficiency with the pure lead sheets of 0.25, 0.35, 0.5, and 1 mm thickness that are standardly used in radiology protection. The mass of the Gd nanocomposite (ϕs = 0.14, 8 mm thickness) X-ray protection screen needed is significantly lighter than that made from concrete, glass, and wood at the same attenuation performance (97–99% attenuation). The synthesized material also introduced in this article, with 36–48% less weight, shows better attenuation proficiency than three other lightweight commercial non-Pb composite products above 73 kVp. The X-ray attenuation efficiency per unit area mass of the Gd composite with ϕs of 0.1 attained the highest value of ∼0.88 (cm2/g) which is equal to that of pure Pb. This work proposes a way to produce an environmentally safe, lightweight composite with prominent X-ray attenuation properties.

Effect of the Sn-Ag addition on the internal stress change and electrochemical properties of lead-based anodes

The corrosion resistance is importantly influenced by the internal stress of the oxide film on lead-alloy anodes. In this article, pure lead anodes and Pb-Sn-Ag alloy anodes are taken as raw materials to study the effect of Sn-Ag addition on the internal stress change and electrochemical properties of oxide film in a chromic acid solution. The structural properties are researched by means of a metallurgical microscope, a Raman spectrometer and an X-ray diffractometer. The electrochemical properties are studied by electrochemical testing methods. During the oxidation process, both anodes behave as the compressive stress, while the internal stress of the Pb-Sn-Ag alloy anode exhibits fewer changes. PbO, which contributes to a compressive stress, is generated first and then turns into PbCrO4 that contributes to a tensile stress. Compared to pure lead anodes, Pb-Sn-Ag alloy anodes possess a better corrosion resistance, which can be maintained for a long time. PbCrO4 tends to weaken the corrosion resistance. The analysis shows that the more internal stresses accumulates, the poorer the corrosion resistance possessed by anodes. Moreover, an equation of σOF=A⋅exp(t/B)+σL is proposed to estimate the internal stress.

Benefits of subcomponent over full-scale blade testing elaborated on a trailing-edge bond line design validation

Abstract. Wind turbine rotor blades are designed and certified according to the current IEC (2012) (International Electrotechnical Commission) and DNV GL AS (2015) (Det Norske Veritas Germanischer Lloyd Aksjeselskap) standards, which include the final full-scale experiment. The experiment is used to validate the assumptions made in the design models. In this work the drawbacks of traditional static and fatigue full-scale testing are elaborated, i.e., the replication of realistic loading and structural response. Subcomponent testing is proposed as a potential method to mitigate some of the drawbacks. Compared to the actual loading that a rotor blade is subjected to under field conditions, the full-scale test loading is subjected to the following simplifications and constraints: first, the full-scale fatigue test is conducted as a cyclic test, wherein the load time series obtained from aeroservoelastic simulations are simplified to a damage-equivalent load range. Second, the load directions are typically applied solely in two directions, often pure lead–lag and flapwise directions which are not necessarily the most critical load directions for a particular blade segment. Third, parts of the blade are overloaded by up to 20 % to achieve the target load along the whole span. Fourth, parts of the blade are not tested due to load introduction via load frames. Finally, another downside of a state-of-the-art, uni-axial, resonant, full-scale testing method is that dynamic testing at the eigenfrequencies of today's blades with respect to the first flapwise mode between 0.4 and 1.0 Hz results in long test times. Testing usually takes several months. In contrast, the subcomponent fatigue testing time can be substantially shorter than the full-scale blade test since (a) the load can be introduced with higher frequencies which are not constrained by the blade's eigenfrequency, and (b) the stress ratio between the minimum and the maximum stress exposure to which the structure is subjected can be increased to more realistic values. Furthermore, subcomponent testing could increase the structural reliability by focusing on the critical areas and replicating the design loads more accurately in the most critical directions. In this work, the comparison of the two testing methods is elaborated by way of example on a trailing-edge bond line design.

METALLIC LEAD ELECTROREFINING FROM RAW MATERIAL IN LEAD - DIETHYLENETRIAMINE COMPLEX SOLUTION

Metallic lead was refined from raw material via electrolysis process in lead - diethylenetriamine (Pb-DETA) complex solution with presence of various additives. The influence of the additives, Pb-DETA concentration, current density and temperature on lead deposition, dendrite formation and electric current performance were studied. The additives strongly affect to dendrite formation and the deposition of lead metal in the Pb-DETA complex solution. The morphology and composition of the electrolyzed lead were analyzed by optical microscope, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). After electrorefining, the impurities were removed and the product was pure lead metal. The lead diethylenetriamine complex solution with three additives as gelatine, dextrine and β-naphthol is promising electrolyte for lead refining via electrolysis process.

GEN-IV LFR development: Status & perspectives

Since Lead-cooled Fast Reactors (LFR) have been conceptualized in the frame of Generation IV International Forum (GIF), great interest has focused on the development and testing of new technologies related to Heavy Liquid Metal (HLM) nuclear reactors. In this frame, ENEA developed one of the larger European experimental fleet of experimental facilities aiming at investigating HLM thermal-hydraulics, coolant chemistry control, corrosion behavior for structural materials, and at developing components, instrumentations and innovative systems, supported by experiments and numerical tools.The present work aims at highlighting the capabilities and competencies developed by ENEA so far in the frame of the liquid metal technologies for GEN-IV LFR.In particular, an overview on the ongoing R&D experimental program will be depicted considering the actual fleet of facilities: CIRCE, NACIE-UP, LIFUS5, LECOR and HELENA.CIRCE (CIRColazione Eutettico) is the largest HLM pool facility presently in operation worldwide. Full scale component tests, thermal stratification studies, operational and accidental transients and integral tests for the nuclear safety and SGTR (Steam Generator Tube Rupture) events in a large pool system can be studied.NACIE-UP (NAtural CIrculation Experiment-UPgraded) is a loop with a HLM primary and pressurized water secondary side and a 250 kW power Fuel Pin Simulator working in natural and mixed convection.LIFUS5 (lithium for fusion) is a separated effect facility devoted to the HLM/Water interaction. HELENA (HEavy Liquid metal Experimental loop for advanced Nuclear Applications) is a pure lead loop with a mechanical pump for high flow rates experiments. LECOR (LEad CORrosion) is a corrosion loop facility with oxygen control system installed.All the experiment actually ongoing on these facilities are described in the paper, depicting their role in the context of GEN-IV LFR development.

Lead paste recycling based on conversion into battery grade oxides. Electrochemical tests and industrial production of new batteries

We present the preparation and characterization of pure lead monoxide obtained through recycling of the lead paste recovered from exhausted lead acid batteries. The recycling is based on a hydrometallurgical procedure reported in a STC Patent, that includes simple chemical operations (desulphurisation, leaching, precipitation, filtration) and a final thermal conversion. Materials obtained by treatment at 600 °C consist predominantly of β-PbO. The electrochemical behaviour of Positive Active Mass (PAM) prepared from different materials (or mixtures) is then investigated and compared. An optimized oxide material, obtained by prolonged (8 h) thermal treatment at 600 °C, consists of pure β-PbO and appears suitable for preparation of battery elements, alone or in mixture with a small fraction (10%–30%) of traditional industrial leady oxide. The resulting battery performances are similar to those obtained from pure leady oxide. In comparison with traditional recycling processes, the proposed method guarantees lower energy consumption, limited environmental impact and reduced operating risk for industry workers.

Electrochemical and anodic behaviors of MnO2/Pb nanocomposite in zinc electrowinning

In this study, the electrochemical and anodic behaviors of MnO2/Pb anodes in electrowinning process were investigated. An accumulative roll-bonding (ARB) method was applied to fabricate MnO2/Pb nanocomposites. The electrochemical properties of the produced anodes were investigated by electrochemical impedance spectroscopy, cyclic voltammetry, electrowinning tests, and scanning electron microscopy. The results indicated that the ARB-process is an appropriate method to develop MnO2/Pb anodes. The produced anodes (Pb–0.5%MnO2-10pass samples) showed a 102% increase in current density compared to pure lead anode. The results of electrowinning tests revealed that Pb–0.5%MnO2-10pass samples had the best anodic performance with a significantly lower corrosion rate, product and electrolyte contamination, slime formation, energy consumption, and a higher current efficiency and consequently, a higher Zn deposition in cathode.

A thermodynamic description of data for pure Pb from 0 K using the expanded Einstein model for the solid and the two state model for the liquid phase

Thermodynamic data for the crystalline and liquid phases of pure lead were critically assessed. A thermodynamic description was obtained using an extended Einstein model for the crystalline phase and a two state model for the liquid phase. The assessment was carried out through careful analysis of the experimental data published in the scientific literature. Additional measurements using enthalpy drop were also carried out in the present work to remove ambiguities in published experimental data.