Lead Monoxide Research Articles

Formula omitted] NMR study of novel Pb–Pb chemical bonding in lead monoxides, α-PbO and β-PbO

α-PbO and β-PbO have been studied with 207 Pb NMR-MAS spectroscopy in the solid state. The 207 Pb NMR chemical-shift tensor in α-PbO is axial, with principal values δ ⊥=3030±5, δ ‖=−270±5, and δ iso=1930±10 ppm. In β-PbO, the 207 Pb NMR powder spectrum is approximately represented by a single non-axial tensor with principal values δ 11=2820, δ 22=2760, δ 33=−1000, δ iso=1525±10 ppm and η=0.024, although there appears to be an overlap of two very similar patterns. Using normal-coordinate analysis, the 207 Pb magnetic shielding tensor is represented as a sum of contributions from separate Pb–O and Pb–Pb interactions. It is shown that Pb–O and Pb–Pb contributions are of the same order of magnitude. A potential underlying relativistic reason for the abnormal Pb–Pb interaction is revealed.

Surveillance of occupational diseases in the United States. A survey of activities and determinants of success.

Managers of state-based occupational disease surveillance programs were interviewed for information on their program's characteristics and factors that contributed to their success. There were 68 programs in 52 jurisdictions (50 states, the District of Columbia and New York City). Reportable conditions ranged from a specific disease to "all occupational diseases". Of these programs, 56% met at least one of their objectives. Conditions associated with successful programs usually had short latency periods, were easily diagnosed, and were related to a workplace hazard. They included agricultural injuries, burns, respiratory diseases, cumulative trauma disorders, and poisonings due to lead, pesticides, or carbon monoxide. Successful programs had larger budgets and more staff than did unsuccessful programs, and also took actions after notification of a condition.

Improved oxides for production of lead/acid battery plates

For many years, the plates of lead/acid batteries have been produced from leady oxide, a mixture of finely divided lead (`free-lead') and lead monoxide. Although this material is generally satisfactory, it suffers from the disadvantages that it is variable in composition and requires complicated and lengthy processing after pasting to remove the residual free-lead. Plates made from leady oxide also require cycling before they achieve their full performance, and this can result in either depressed initial capacity or additional processing cost. There is a growing trend towards the use of pure lead monoxide (β-PbO) for the production of positive plates. This material is particularly valuable in valve-regulated batteries where cell-to-cell uniformity is essential for proper control of battery performance. It also reduces processing cost since it does not require time-consuming curing to remove free-lead. Red lead (Pb3O4) is also being more widely used in industrial batteries since it reduces formation time, and improves initial and high-rate performance. The methods of production of leady oxide, β-PbO and red lead are briefly reviewed and the characteristics of battery-grade materials are described. Particular emphasis is placed on optimum particle-size distribution, and how this can affect the battery performance. The benefits in processing and performance are described together with information on how pure litharge and red lead are used in battery plates.

Infrared spectra of the reaction products of laser ablated lead atoms and oxygen molecules in condensing argon and nitrogen

Reactions of laser ablated lead atoms with oxygen molecules in condensing argon and nitrogen streams gave the PbO, OPbO, Pb(O2), OPb(O2), PbOPb, Pb2O2, PbPb(O2), and Pb4O4 molecules. The formation of lead monoxide and linear dioxide molecules is the main difference with thermal evaporation experiments. The linear OPbO isomer was identified from oxygen-18 and lead (natural abundance) isotopic substitution in the strong antisymmetric stretching absorption at 764.8 cm−1; a weak ν1+ν3 combination band was observed at 1423.4 cm−1. Two bands [ν1=728.7 cm−1 (Ar) and 730.6 cm−1 (N2) and ν2=437.3 cm−1 (Ar) and 449.6 cm−1 (N2)] are assigned to the cyclic isomer Pb(O2) based on oxygen isotopic substitution. The position of the O–O stretching fundamental shows that Pb(O2) is a peroxidelike molecule. The secondary reaction Pb(O2)+Pb gives a large yield of cyclic Pb2O2 and allows observation of very strong antisymmetric Pb–O stretching fundamentals and combination bands with the two symmetric stretching fundamentals. Density functional frequency calculations with effective core potentials support assignment of the observed infrared absorptions.

Time resolved XAS study of a phase transition: The polymorphic transformation of tetragonal to orthorhombic PbO

We present a time resolved XAS study of the phase transition of tetragonal to orthorhombic lead monoxide PbO α → PbO β , occuring at 490 °C. XAS experiments were carried out on a fast energy dispersive spectrometer and full Pb L 3 XAS spectra were periodically recorded as a function of the sample temperature within the range 100–700 °C. The time resolution is about 1 s. XAS experiments give evidence for a dynamical two-step solid state transformation.The phase transition appears to be initiated by O atom displacements within the PbO 4 structural pyramidal unit. Pb atom displacements seem to occur in a second stage of the phase transition.

X-ray electron spectroscopic investigation of the structure of double lead silicate glasses

The method of x-ray electron spectroscopy is used to investigate lead silicatexPbO(1 -x) · SiO2 (x - 0.3, 0.4, 0.5, 0.55, 0.667) glasses. The concentration dependences of the spectra of inner Pb4f, Si2p, and Ols levels led to the conclusion that for low contents of PbO, lead is present in the glass in the form of modifying ions, whereas in high concentrations, it plays the role of glass former. Restructuring in the glass occurs for about 50% molar concentration of PbO. The Pb - O bond in the glass is more ionic than in PbO. With an increase in the PbO content in the glass, the Pb - O bond becomes closer to that of lead monoxide, i.e., is more covalent.

Electronic structure of the lead monoxides: Band-structure calculations and photoelectron spectra.

PbO is a layer compound which exists in two polymorphic forms, a red tetragonal (\ensuremath{\alpha}) and a yellow orthorhombic (\ensuremath{\beta}) modification. Ab initio band-structure calculations are presented for both phases. The calculated energy gaps are in agreement with optical data. The band-structure calculations are used to discuss the chemical bonding in the \ensuremath{\alpha} and \ensuremath{\beta} phases. It is found that the Pb 6s states are strongly hybridized with O 2p orbitals. Thus the so-called Pb (6s${)}^{2}$ lone pair in PbO takes part in the chemical bonding, and cannot be considered as an inert pair. Photoelectron spectra of the valence band and of some core levels are presented for \ensuremath{\alpha}- and \ensuremath{\beta}-PbO. The observed valence band is in good agreement with the calculated band structure.

New information on the composition of bint al Dhahab, a mixed lead monoxide used as a traditional medicine in Oman and the United Arab Emirates.

X-ray diffraction and X-ray micro-analyser studies of the traditional medicine bint al dhahab confirm that it is composed of two polymorphs of lead monoxide (PbO). These studies also show the presence of cadmium and a third complex monoxide of lead containing antimony. Bulk analyses show that the substance contains approximately 91 g of lead monoxide, 600 mg of antimony oxide, and 50 mg of cadmium per 100 g of bint al dhahab. This new information may assist physicians to devise appropriate treatment regimens for patients presenting with symptoms of toxicity.

Crystal Structure and Growth Mechanism of Lead Monoxide Thin Films Produced by Pulsed Laser Deposition

Crystal Structure and Growth Mechanism of Lead Monoxide Thin Films Produced by Pulsed Laser Deposition

Study of the oxygen-sensitive behavior of yellow lead oxide by defect chemistry

The dependence of electrical conductivity on ambient oxygen partial pressure of yellow lead oxide ceramics is investigated. A conduction type transition is observed for pure PbO as the oxygen partial pressure varies through a certain value that corresponds to the minimum conductivity measured, and the conductivity is found to vary with −1/4 and +1/4 power of the oxygen partial pressure in the n region and the p region, respectively. It is also found that the conduction transition point can be moved to lower or higher oxygen partial pressures with acceptor or donor impurities doped into PbO. A point defect model of doubly charged oxygen vacancies with concentration affected by impurities is presented for PbO in the investigation and it is demonstrated that the theory is in good agreement with the experimental results.

Optical Characterization of Lead Monoxide Films Grown by Laser-Assisted Deposition

The Raman spectra of PbO films, grown by laser-assisted deposition (LAD) at different substrate temperatures are investigated. The spectra of the films, deposited on amorphous, single crystal quartz and polycrystal PbTe substrates, are compared with the Raman spectra of tetragonal and orthorhombic powder samples. The phonon frequencies determined in our experiment with powder samples coincide fairly well with those obtained by Adams and Stevens, J. Chem. Soc., Dalton Trans., 1096 (1977). Thus the Raman spectra of the powder samples presented in this paper can be considered as unambiguous characteristics of the two different PbO crystal phases. It was concluded that the Raman scattering may serve as a tool for identification of PbO films and their crystal modifications. On the basis of this investigation it was concluded that the film structure changes from orthorhombic to tetragonal with increased substrate temperature, and that the nature of the substrate influences the crystal structure of the films. On the basis of the Raman spectra of the β-PbO films with prevailing (001) orientation of crystallization, an assignment of the modes is proposed.

Effect of PbO polymorphic phases on PLZT ceramics properties

Abstract The influence of the two lead monoxide polymorphic phases, litharge with tetragonal crystal structure and massicot with orthorhombic structure, on some properties of the (Pb1−xLax)(Zr0.65Ti0.35)O3 ceramics, with x=0.09, was investigated. Ceramic samples were prepared by oxides mixture technique using different amounts of massicot and litharge PbO. Results, based on X-ray diffraction patterns, remanent polarization and dielectric measurements, show that PbO form does not affect the final crystal structure but causes changes on the dielectric permittivity temperature dependence.

Effect of VA Elements on the Semiconducting Properties of the Anodic Plumbous Oxide Film (I)

用交流阻抗法铅、铅砷、铅锑和铅铋合物在４．５ｍｏｌ·Ｌ＾－１Ｈ２ＳＯ４溶液（２０℃）中，以０．９Ｖ（ｖｓ．Ｈｇ／Ｈｇ２ＳＯ４）极化２ｈ而形成的阳极膜的半导体性质。根据Ｍｏｔｔ－Ｓｃｈｏｔｔｋｙ图，此种膜为ｎ型半导体。Ｐｂ，Ｐｂ－ｌａｔ％Ａｓ，Ｐｂ－ｌａｔ％Ｓｂ和Ｓｂ－ｌａｔ％Ｂｉ上膜的平带电位分别为－０．９５，－１．１、－１．０，－１．１Ｖ（ｖｓ．Ｈｇ／Ｈｇ２ＳＯ４）；相应的施主密度分别为０．８２

The role of biochemical markers in peripheral body fluids in assessment of human neurotoxicity

To date the evaluation of chemically-induced neurotoxic effects on humans has been dependent mostly on electrophysiological measurements, neurobehavioral tests and biological exposure assessment. However, recently attempts have been made to develop biochemical parameters in peripheral body fluids which can be easily obtained from humans and which can represent markers for the same parameters in nervous tissue. The approach of this kind is logically based on the following facts: 1) Blood cells (e.g., platelets and lymphocytes) possess some characteristics of monoaminergic neurons such as the existence of storage vesicles of monoamines, membrane neurotransmitter receptors, high affinity uptake sites and neurotransmitter-related metabolizing enzymes. 2) Leakage of nerve-specific markers from nervous tissue to peripheral body fluids may occur following damages of target neuronal cells or macromolecules. 3) Quantitative and/or qualitative alterations of peripheral biochemical markers (e.g. neurotransmitter receptors) can be induced by the regulation mechanisms of neuronal, endocrinal and immunologic interactions when the nervous functions are perturbed by various exogenous or endogenous factors. Erythrocyte acetyl cholinesterase (AChE), free erythrocyte protoporphyrin (FEP), lymphocyte neurotoxicity target enzyme (NTE), blood aminolevulinic acid dehydratase (ALA-D), and carboxyhemoglobin (CO-Hb) are well-known peripheral markers of the effects induced by organophosphates (AChE, NTE), lead (FEP, ALA-D) and carbon monoxide (CO-Hb). Many studies have been made on the effects of organic solvents, heavy metals and pesticides on neurotransmission parameters in blood cells such as neurotransmitter uptake, receptor binding and enzyme activity. This paper summarizes the present knowledge on the development and clinical applications of some peripheral biochemical markers such as neurotransmission parameters in blood cells and neuronal or glial cell marker proteins in CSF, blood and urine. The role of these peripheral biochemical markers in the assessment of environmental chemically-induced human neurotoxicity is also discussed.

Effect of VA Elements on the Semiconducting Properties of the Anodic Plumbous Oxide Flim(II)

Effect of VA Elements on the Semiconducting Properties of the Anodic Plumbous Oxide Flim(II)

Estimation of rotational temperature of the source emitting the spectrum of PbO molecule

The (1, 0), (0, 1) and (0, 2) bands ofD→X system of lead monoxide have been excited in RF discharge source and photographed in the seventh order of a 2-meter PGS. Intensity records of the rotational lines have been obtained. Rotational constants and the intensity measurements ofQ andP branch lines of the above three bands andJ numbering are used to calculate the effective rotational temperature of the source emitting the spectrum of208Pb16O molecule.

Correlation between the structural defects induced by ball-milling of Pb 3O 4 and the structure of PbO yielded from its thermal decomposition

The influence of grinding in a high planetary ball-mill on the texture and thermal stability of Pb 3O 4 has been studied. The results obtained show that the crystallite size decreases while the level of microstrains increases upon increasing the grinding time. The Pb 3O 4→PbO conversion temperature decreases by increasing the grinding time of the precursor when the orthorhombic phase of PbO (massicot) becomes stabilized with regards to the tetragonal modification (litharge). The analysis of the X-ray diffraction profiles of the lead monoxide obtained from the thermal decomposition of Pb 3O 4 demonstrates that PbO keeps memory of the lattice imperfections of Pb 3O 4. Moreover, higher the grinding time of Pb 3O 4, higher the reactivity of the resulting PbO sample towards reoxidation.

A photocurrent imaging study of the distribution of lead monoxide in corrosion layers on lead/acid battery grids

It is widely believed that α-PbO is a principal contributor to premature capacity loss in lead/acid batteries via the formation of a resistive ‘barrier’ layer in the corrosion zone of the positive grid. While batteries employing PbCa grids are more prone to capacity loss than those using PbSb grids, a definitive relationship of such behaviour with α-PbO distribution on either of these two alloys has yet to be demonstrated. In the work reported here, ex situ scanning laser imaging has been used to reveal the distribution of the α-PbO phase across paste/corrosion layer/grid transverse sections of cycled PbCa grids. The technique has been successfully extended to in situ measurements of localized photocurrent at potentials that correspond to the environment of the positive plate in a lead/acid battery. It has been demonstrated that α-PbO films can be mapped at a resolution that provides an intimate insight into their influence on battery operation.

Role of particle evaporation during synthesis of lead oxide by aerosol decomposition

The role of product evaporation during lead monoxide (PbO) powder generation by aerosol decomposition (spray pyrolysis) was investigated at various temperatures in a flow reactor. Particles consisting of phase pure litharge and a mixture of litharge and massicot were formed with the dominant phase changing from litharge to massicot as the pyrolysis temperature was increased. Scanning electron microscopy showed particles produced at lower temperatures had a lumpy surface morphology and at higher temperatures appeared to be solid, indicated by the faceted surfaces and a plate-like morphology. Evaporative losses of PbOx, to the reactor walls were observed due to the substantial vapor pressure of PbOx. A simple model was developed that accounts for particle evaporation and mass transfer of lead oxide vapor to the reactor walls. This model suggested that the loss of lead oxide to the reactor walls was limited by diffusional transport of lead oxide vapor to the reactor walls.

The elucidation of hydrogen and anion adsorption on Pt(111) through the co-adsorption of metal adatoms and carbon monoxide

Copper, lead and carbon monoxide adsorbates have been used to probe the adsorption processes on a Pt(111) electrode in H 2SO 4 and HClO 4 solutions. All three adsorbates cause inhibition of hydrogen adsorption in both solutions and a decrease of the anomalous peak recently ascribed to HSO 4 − adsorption. The “butterfly” peak in HClO 4 solution is slightly perturbed by Cu and Pb adatoms. Evidence was found that the species responsible for the anomalous peak for Pt(111) in H 2SO 4 solutions is not H ads and that HSO 4 − probably interacts with three Pt(111) sites. A twofold interaction of HSO 4 − with the Pt(111) surface, however, cannot be ruled out completely. In HClO 4 solutions the Cu and Pb adatoms do not cause any decrease of the charge associated with the “butterfly” peak. These results can be explained in terms of PtOH as the species involved with the “butterfly” peak. The electrosorption valence of HSO 4ads − is unity, which indicates a strong interaction with the surface and a high charge transfer. The Temkin interaction parameter for H ads is fRT = 42 kJ mol −1, which provides evidence for a large repulsive interaction of H ads on the Pt(111) surface. It decreases in the presence of Cu and CO adsorbates. These results illustrate the usefulness of the competitive adsorption of various adsorbates in probing adsorption processes on electrode surfaces.