In order to improve our understanding of how the goethite crystal structure is affected by the incorporation of metals (and by variations in the amount of the incorporation), and to review any possible synergistic and antagonistic effects of co-metals, the present investigation focused on the incorporation of multiple (di-, tri-, and tetra-) metals, i.e. Cr, Zn, Cd, and Pb, in the goethite crystallographic structure. A series of single- and multi-metal M-Cr/Zn/Cd/Pb-substituted goethites with M/(M+Fe) molar ratios = 0.10 were prepared. The general sequence of metal entry in single-metal substituted goethites was Zn = Cr > Cd > Pb and in multi-metal-substituted goethites was Zn > Cr ⩾ Cd > Pb. Simultaneous incorporation of Cr, Zn, Cd, and Pb up to 10.5 mole % was achieved in goethite. Synchrotron X-ray diffraction and extended X-ray absorption fine structure (EXAFS) techniques were employed to assess the structural characteristics of the synthesis products. Rietveld refinement of XRD data showed small changes in unit-cell parameters and Fe/M-Fe/M distances due to M substitution(s). A typical goethite-like crystalline structure remained intact, however. The unit-cell parameters were mutually, linearly correlated, though Fe/M-Fe/M distances were not, indicating that complex changes occurred at the local scale. In single-metal substituted goethites, incorporation of Cr reduced the unit-cell volume by 0.13% while that of Zn, Cd, and Pb increased it by 1.09, 3.58, and 0.56%, respectively. The changes in multi-metal-substituted goethites appeared to be the complex combination of that of the individually incorporated metals. The X-ray absorption near edge structure study of Pb-substituted goethites showed that the majority of associated Pb was Pb2+, while Pb4+ was preferred over Pb2+ in the bulk structure. Measurements by EXAFS at the Fe K-edge indicated that the Fe polyhedra contracted in the presence of Cd2+ and Pb2+, providing room for the substitution of larger cations. Measurements by EXAFS at the Cr and Cd K-edges indicated symmetric Cr/Cd polyhedra with single Cr/Cd-O distances and, at Fe and Zn K-edges and the Pb LIII-edge, indicated asymmetric polyhedra with two sets of Fe/Zn/Pb-O distances. The Zn octahedra were possibly Zn(OH)4O2, which enlarged the metal-metal corner-sharing distance to 3.86 Å. This configuration of ligands around the Zn2+ cation might occur to balance local charges. Symmetric polyhedra appeared to reduce steric strains in the structure, compared to the asymmetric polyhedra. The result was that Cr enhanced the incorporation of Zn, Cd, and Pb, while the converse was true for Zn.

In the present study, the levels and probable public health risks of selected metals (Fe, Mn, Cu, Zn, Ni, Cd and Pb) in nine wheat flour samples collected from Amhara, Oromia, South region, and the Strategic Food Reserve Agency were determined using FAAS and compared with results of prior studies and critical level. The wet digestion method using 65 % HNO3 and 72 % HClO4 in 300°C for 3 h was used when preparing the sample. Validation of the optimised digestion method was assessed using the spiking method, and an acceptable percent recovery from all metals. The levels of Fe, Cu, Mn, Zn, Ni and Cd ranged between 8⋅5297 and 11⋅1535, 1⋅633 and 4⋅2346, 3⋅1875 and 8⋅5313, 2⋅3589 and 2⋅7719, 0⋅154 and 0⋅854, and 0⋅0411 and 0⋅216 mg/kg, respectively, for Ethiopian wheat flour, while the level of Fe, Cu, Mn, Zn, Ni, Cd and Pb were ranged between 8⋅0099 and 8⋅1089, 1⋅663 and 1⋅6691, 4⋅5625 and 4⋅6250, 2⋅3015 and 2⋅3072, 0⋅9423 and 1⋅1346, 0⋅1593 and 0⋅1606, and 0⋅13 and 0⋅1381 mg/kg, respectively, for imported wheat flour. However, Pb had a concentration of less than 0⋅043 mg/kg for Ethiopian wheat flour. Findings indicate that Ethiopian wheat is comparatively higher in Fe, Mn, Cu, Zn and Cd, but lower in Ni and Pb than imports. From the result of the study, it can be concluded that the level of heavy metals determined in this study was within the permissible limit, and no probable health risk because both the Hazard quotient (HQ) and the Hazard Index (HI) are found to be below 1⋅0 regarding study metals.

Using general-purpose photovoltaic device model, we have simulated the operation and functionality of a working Sn perovskite/Cu2O hole transport layer (HTL)/Cu back-contact device versus a standard Pb perovskite/Spiro HTL/Ag back-contact device. The results are extremely promising in that they showcase comparable cell efficiencies, with the Sn perovskite/Cu2O HTL/Cu back-contact device showing a highest 22.9% efficiency [Jsc of 353.4 A/m2, Voc of 0.84 V, fill factor (FF) of 0.77] at 427 nm active layer thickness compared with 24.6% of the standard Pb perovskite/Spiro HTL/Ag back-contact device (Jsc of 356.8 A/m2, Voc of 0.82 V, FF of 0.84) at the same active layer thickness. Jsc, Voc, and FF kinetics reveal that the Sn perovskite/Cu2O HTL/Cu back-contact device can perform better by reducing the recombination centers both within each layer matrix and in the interfacial contacts.

The field of lead-free piezoceramics, which aims to replace lead zirconate titanate (PZT) and related perovskite materials, has been vibrant for almost 15 years. Once the science in this field attained a certain stage of maturity, materials with properties better than PZT have appeared, and the first products are about to reach the marketplace. This article describes the three most promising lead-free piezoceramics currently under discussion to replace PZT. Each has a pronounced property profile geared for specific applications. Guidelines for directions for fundamental future research on as well as technology transfer to industry of lead-free piezoceramics are provided.

The search for lead-free alternatives to Pb(Zr,Ti)O3 (PZT) piezoelectric ceramics has become a major topic in functional materials research due to legislation in many countries that restricts the use of lead alloys and compounds in commercial products. This article examines both the necessity for regulation and the impacts those regulations have created in the context of piezoelectric materials. It reviews the toxicity of lead, describes current legislation to control the spread of lead in the environment, and attempts to define the risks associated with the manufacture, use, and disposal of lead-based piezoelectric materials. The consequences of current legislation, both intended and unintended, are examined.

Lead, zinc and arsenic mobilization/attenuation processes during interactions between smelter slag and water show differences depending on the origin of the slag. The studied samples, waste from ore and car-battery processing, were submitted to long-term (365 days) batch leaching at two different initial pH values. The leachate analyses were input to the EQ3NR speciation-solubility code to speciate the solutions and determine the degree of saturation with respect to different phases, and a mineralogical investigation was made of the newly formed phases. An ‘oxidizing’ scenario can be proposed for slag waste disposal, considering that cerussite (PbCO3) at pH >6 becomes a major solubility-controlling phase for Pb, and newly formed hydrous ferric oxides (HFO – common secondary phases under oxidizing conditions) efficiently adsorb As. No efficient scavenging mechanism was found for Zn, which was progressively leached from the slag and in particular from the ore-processing slag. Quenched glass-rich slag from old car-battery processing was found to release significant amounts of Pb, especially in acidic environments. Neither slag would therefore be suitable for recycling for civil engineering purposes. Conversely, extremely low releases of Pb, Zn and As were observed for recent car-battery processing slag, which could therefore be considered for road construction.

The previously unknown crystal structure of the basic lead nitrate Pb2(OH)3(NO3) has been determined using single-crystal X-ray diffraction data (Mo-Kα radiation, CCD area detector). The compound is orthorhombic, space group Immm, with a = 8.314(2), b = 8.545(2), c = 17.210(3) Å (R1 = 2.78% for 940 ‘observed’ reflections with Fo > 4σ(Fo)). The layered structure contains a previously unknown cuboid [Pb8(OH)12]4+ cluster and NO3 groups. The study used crystals formed by anthropogenic processes on a medieval mine dump, probably involving black gunpowder used in the blasting of ore. Pb2(OH)3(NO3) is associated with a second nitrate, Pb13O8(OH)6(NO3)4, which was previously designated as “Pb3O3(OH)4(NO3)2” or “Pb3(OH)5(NO3)”. It is rhombohedral, space group , with a = 10.263(1), c = 25.454(5) Å, and a structure solution is in complete agreement with an independent single-crystal study by Li et al. (2001). Probable hydrogen bonds in Pb2(OH)3(NO3) are indicated. Reported data on clusters and lead hydroxide and oxide nitrates are summarized and discussed critically. The probable conditions of formation of the studied samples are evaluated.

The weathering and oxidation of mine tailings has the potential to contaminate water and soil with toxic elements. To understand the mechanisms, extent and products of the long-term weathering of complex Bolivian tailings from the Cerro Rico de Potosí, and their effects on As, Pb, P and Sb cycling, three-year long laboratory column experiments were carried out to model 20 years of dry- and wet-season conditions in the Pilcomayo basin. Chemical analysis of the leachate and column solids, optical mineralogy, X-ray diffraction, scanning electron microscopy, electron probe microanalysis, microscale X-ray absorption near edge structure spectroscopy, Bureau Commun de Référence sequential extraction and water-soluble chemical extractions, and speciation modelling have shown that the weathering of As-bearing pyrite and arsenopyrite, resulted in a loss of 13–29% of the original mass of As. By contrast, Pb and Sb showed much lower mass losses (0.1–1.1% and 0.6–1.9%, respectively) due to the formation of insoluble Pb- and Sb(V)-rich phases, which were stable at the low pH (~2) conditions that prevailed by the end of the experiment. The experiment also demonstrated a link between the cycling of As, Sb, and the oxidation of Fe(II)-bearing sphalerite, which acted as a nucleation point for an Fe-As-Sb-O phase. Phosphorus was relatively immobile in the tailings columns (up to 0.3% mass loss) but was more mobile in the soil-bearing columns (up to 10% mass loss), due to the formation of soluble P-bearing minerals or mobilization by organic matter. These results demonstrate the influence of mine tailings on the mobility of P from soils and on the potential contamination of ecosystems with As, and strongly suggest that these materials should be isolated from fluvial environments.

Zeolite and cellulose-acetate nanocomposites were fabricated in this study using a combination of melt blending and solution mixing. The nanocomposites were optimized for heavy metal adsorption using spiked lead and cadmium solutions. Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and Powder X-Ray diffraction crystallography were used for physical characterization. Fourier Transform Infrared spectra showed a reduction of the hydroxyl peak for cellulose acetate and that of the residual silanol group for zeolites symbolizing bonding during nanocomposite formation. Scanning Electron Microscope results showed an increase in voids with zeolite loading in the nanocomposites, a useful characteristic of good adsorbents. Powder X-ray diffraction crystallography results showed a reduction in 2 theta values for the nanocomposites due to penetration of the polymer into the silicate lattice e.g. zeolite 2 theta peak at 7.44° reduced to 7.09° in the nanocomposites signifying an increase in crystal lattice d- spacing from 1.188 nm to 1.247 nm. The nanocomposites adsorbed a maximum of 97.20% lead ions and 85.06% cadmium ions from solution.

Lead is one of the environmental pollutants with cardiovascular toxicity. The embryos are particularly sensitive to lead exposure, because it can move through the blood-placental barrier and the blood-brain barrier easily during embryonic development. Cerebral cavernous malformations 3 (CCM3) gene plays an important role in cardiovascular development, mainly affecting cell proliferation, differentiation and apoptosis. In this study, we established a blood vessel development model of mouse embryos in order to imitate human people with CCM3 genes defects and exposing to environment toxin Pb in utero. We would like to determine the interaction of Pb and CCM3 gene on vascular development, and to explore the mechanisms. We found that the yolk sac of CCM3 heterozygous mice embryo showed abnormal morphology at E11.5 after lead treatment comparing with wild type (WT) mice without lead exposure, meanwhile it showed more angiogenesis and vascular remodeling in the hematoxylin and eosin stained sections of the CCM3+/− yolk sac with lead exposure. We also found that the similar effect of Pb and CCM3 gene on mitochondrial DNA (mtDNA) copy number in vivo and in vitro. Mitochondrial morphology and function also changed in primary human umbilical vein endothelial cells after lead exposure. Besides, it was found that the HIF-1α and TFAM which have close relationship with mtDNA biogenesis showed similarly increasing messenger RNA expression in both human and mouse-derived primary cells with lead treated and CCM3 gene knockout. All of the above results indicated that lead and CCM3 might damage endothelial cells through mitochondria pathway and eventually both affected angiogenesis.

Perovskite solar cells are promising for realizing high power conversion efficiency (PCE) with low manufacturing costs, but efficient coating methods are needed for commercialization. Here, a gas blowing method was used to fabricate perovskite solar cells and was found to create a smooth perovskite layer and to prevent voids in large-area cells, when organic materials were used as scaffolds for forming the perovskite. A PCE of 13% in a 1 cm2 active area is achieved by tuning the band-gap energy of MAPbX3 via substitution of Br for I ions in X sites. Incorporation of a poly(3,4-ethylenedioxythiophene) hole transport layer with a higher work function increased the open circuit voltage of the solar cells. All layers of the cells were fabricated at low temperatures (<140 °C), which makes it possible to incorporate a polymer substrate for producing flexible solar cells and high-throughput fabrication.

In this work, a planar heterojunction superstrate n-i-p device based on Zn(O,S) electron transport layer and CsPbI2Br absorber material at 1.93 eV bandgap is presented. The CsPbI2Br films are deposited using a 2-step atmospheric solution deposition process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence (PL). Best device with an efficiency of 12.34 % and 11.94% in reverse and forward scans respectively and stabilized power output of 12.14 mW/cm2 has been demonstrated via atmospheric solution processing with minimal hysteresis between forward and reverse scans. The devices show voltage dependent current collection as well as light-dark crossover in forward bias. Light soaking tests at 65 °C and 1-sun at Voc, resulted in open-circuit voltage and fill-factor degradation. Electroluminescence (EL) after 100 hours of light soaking shows a reduction in overall EL intensity as well a shift in emission to lower wavelength. The devices exhibit a positive temperature coefficient of about 0.14 %/°C. It is found that Zn(O,S) is a viable alternative electron transport layer to replace TiO2. By replacing methylammonium cation with cesium and addition of Br has improved the stability of the perovskite phase.

In semiconductor system for solar-energy utilization by photoelectrochemical (PEC) water splitting, the effective absorption of visible light and the efficient separation and transfer of photogenerated charge carriers are still of key importance. In this manuscript, composite photoanodes of PbO sensitized ZnO nanorod arrays were prepared by a two-step hydrothermal process and used as anodes for PEC test under visible-light irradiation. The photocurrent achieved the highest value of 94 μA cm−2 at 0.8 V (versus Ag/AgCl electrode) when the amount of Pb source was optimized to form only a thin layer (a few nanometers) of PbO nanoparticles on the surfaces of ZnO nanorods. Such a nanostructure enabled the visible-light absorption, and also ensured the sufficient contact of PbO with ZnO to form junction with a type II band alignment and the sufficient contact with aqueous solution to form interfaces, thus facilitating the excitation, separation, and transfer of charge carriers to generate photocurrent and finally enhancing the PEC activity.

Soap formation in traditional oil paintings occurs when heavy-metal-containing pigments, such as lead white, 2Pb(CO3)2·Pb(OH)2, and lead-tin yellow type I, Pb2SnO4, react with fatty acids in the binding medium. These soaps may form aggregates that can be 100-200 μm in diameter, which swell and protrude through the paint surface, resulting in the degradation of the paint film and damage to the integrity of the artwork. In addition, soap formation has been reported to play a role in the increased transparency of paint films that allows the painting support, the preparatory drawing, and the artists’ alterations to become visible to the naked eye. The factors that trigger soap formation and the mechanism(s) of the process are not yet well understood. To elucidate these issues, chemical and structural information is necessary which can be obtained by solid-state 207Pb, 119Sn, and 13C nuclear magnetic resonance (NMR). In the present study, a combination of 207Pb NMR pulse sequences was used to determine accurately the NMR parameters of lead-containing pigments and lead carboxylates known to be involved in soap formation, such as lead palmitate, lead stearate, and lead azelate. These results show that the local coordination environment of lead azelate is different from lead palmitate or lead stearate and therefore it is unlikely that lead azelate would be incorporated into an ordered structure containing lead palmitate and lead stearate. In addition, the chemical shifts of the pigments obtained are different from those of the soaps, demonstrating that 207Pb NMR is useful in characterizing the components when present in a mixture, such as a paint film. The NMR methods discussed can also be applied to other Pb-containing cultural heritage materials, electronic and optoelectronic materials, superconducting materials, and environmentally contaminated materials.

Hybrid halide perovskites represent one of the most promising solutions toward the fabrication of all solid nanostructured solar cells with improved efficiency and long-term stability. This article aims at investigating the structural properties of the iodide/chloride mixed-halide perovskites and correlating them with the photovoltaic performances of the related sensitized solar cells. We found out that, independently on the components ratio in the precursor solution, Cl incorporation, in a I-based structure, is possible only at relatively low concentration levels (below 3-4%). However, even if the material band-gap remains substantially unchanged, incorporation of Cl as a dopant dramatically improves the charge transport within the perovskite layer, explaining the outstanding performances of meso-superstructured solar cells based on this material.

An epitaxial shell of cadmium sulphide is grown on lead sulphide quantum dots in order to reduce the concentration of surface defects. Thin solid films of these core/shell materials are found to have low carrier concentrations due to effective surface passivation which reduces the number of dangling bonds. In this paper PbS/CdS is used as a quasi-intrinsic layer in p-i-n photovoltaic devices where PbS acts as the p-layer and ZnO the n-layer. By studying different permutations of these layers and the degree of PbS p-type doping by annealing we optimise fill factor and open-circuit voltage.

The application of micro-fourier transform infrared (FTIR) mapping analysis to thermoelectric materials towards identification of doping inhomogeneities is described. Micro-FTIR, in conjunction with fitting, is used as analytical tool for probing carrier content gradients. The plasmon frequency ωP2 was studied as potential effective probe for carrier inhomogeneity and consequently doping differentiation based on its dependence of the carrier concentration. The method was applied to PbTe-, PbSe- and Mg2Si- based thermoelectric materials.

Poly(acrylonitrile) fibers are used in the manufacture of activated carbon fibers, which are activated with phosphate groups for the removal of lead ions in aqueous solutions. Removal of lead ions is performed in a water bath at 30°C. Trough isotherm models of Langmuir and Freundlich analyzed the aqueous solution. Kinetic analysis is performed using the model pseudo-first and pseudo-second order. The result show that adsorption equilibrium is adjusted to the Freundlich model and the kinetic model of pseudo-second order led to the best fit correlation.

Even though the crystal structure of lead telluride (PbTe) has been extensively studied for many years, we discovered that the structure has a strong tendency to form Pb-depleted disks on {001} planes. These disks are around 2–5 nm in diameter and less than 0.5 nm in thickness, with a volume density of around 9 × 1017 cm−3, resulting in lattice strain fields (3–20 nm) on both sides of the disks along their normal directions. Moreover, such disks were also observed in Pb-rich Pb1.3Te, Pb-deficient PbTe1.3, and thallium (Tl)-doped Tl0.01Pb0.99Te and Tl0.02Pb0.98Te crystals. Because of the effects of diffraction contrast imaging by transmission electron microscopy and orientations of the crystals, these native lattice strain fields were incorrectly recognized as precipitates or nanoinclusions in PbTe-based materials. This discovery provides new insight into the formation mechanism of the precipitates or nanoinclusions in PbTe-based materials.

The ion beam synthesis of Pb nanoparticles (NPs) in silica/silicon films is studied in terms of the combination of a two-step annealing process consisting of a low temperature long time aging treatment followed by a high temperature short time furnace annealing. The samples are analyzed through Rutherford Backscattering Spectrometry and Transmission Electron Microscopy. The aging process leads to the suppression of the classical homogeneous nucleation of metallic Pb NPs in the silica, thus promoting Pb redistribution during the high temperature annealing. This causes the formation of dense bi-dimensional NP arrays located at the silica-silicon interface, presenting small size dispersion.