Lead-containing Materials Research Articles

Recycling efficiency optimization of tungsten-filled Vinyl-Methyl-Silicone-based flexible gamma ray shielding materials

Tungsten has been widely used for gamma-ray and X-ray radiation shielding, which is one of the main elements of shielding materials. Compared with traditional lead-containing shielding materials, tungsten-containing shielding materials have several advantages, such as good chemical stability, a high melting point and relative environmental friendliness. Considering the recycling of resources, the optimization of pyrolysis temperature and pyrolysis duration of tungsten-filled Vinyl-Methyl-Silicone-based flexible shielding materials needs to be studied. In this paper, these tungsten-filled Vinyl-Methyl-Silicone-based flexible shielding materials were initially recycled using pyrolysis. Subsequently, the crystal structures, surface chemical states and the tungsten concentration after pyrolysis in an argon atmosphere were characterized. In order to increase the tungsten recycling rate, the pyrolyzed samples were further recycled using the ultrasonic cleaning method. Furthermore, the influence of ultrasonic cleaning on tungsten recycling rate and surface morphologies was characterized and analyzed. It is found that the tungsten recycling rate of tungsten-filled Vinyl-Methyl-Silicone based flexible gamma/X-ray shielding material was around 69.9 wt%-81.6 wt% by using the pyrolysis method, while the recycling rate of tungsten can exceed 90.0 wt% by ultrasonic cleaning after pyrolysis.

Piezoelectricity in chalcogenide perovskites

Piezoelectric materials show potential to harvest the ubiquitous, abundant, and renewable energy associated with mechanical vibrations. However, the best performing piezoelectric materials typically contain lead which is a carcinogen. Such lead-containing materials are hazardous and are being increasingly curtailed by environmental regulations. In this study, we report that the lead-free chalcogenide perovskite family of materials exhibits piezoelectricity. First-principles calculations indicate that even though these materials are centrosymmetric, they are readily polarizable when deformed. The reason for this is shown to be a loosely packed unit cell, containing a significant volume of vacant space. This allows for an extended displacement of the ions, enabling symmetry reduction, and resulting in an enhanced displacement-mediated dipole moment. Piezoresponse force microscopy performed on BaZrS3 confirmed that the material is piezoelectric. Composites of BaZrS3 particles dispersed in polycaprolactone were developed to harvest energy from human body motion for the purposes of powering electrochemical and electronic devices.

Synthesis of Lead-Containing Glass Crystalline Materials with Various Crystallization Nucleators

Synthesis of Lead-Containing Glass Crystalline Materials with Various Crystallization Nucleators

Design and parametric optimization of lead free perovskite based tandem solar cell for higher efficiency

A critical concern is the creation of effective and eco-friendly photovoltaic materials. The non-toxic perovskite substance methyl ammonium germanium tri-iodide (MAGeI3) has several applications in tandem solar cells. In this research, the efficiency of a multi-junction tandem solar cell with MAGeI3 as the absorbent layer in the top cell and FeSi2 as the absorbent layer in the bottom cell was examined by a thorough simulation utilising SCAPS-1D software. The simulation took into account several variables, including the thickness, energy level, bandgap, and carrier concentration of the various layers. According to the simulation’s findings, the efficiency is 27.25% and the fill factor (FF) is around 80%. MAGeI3 is a safe and effective substitute material compared to other lead-containing perovskite materials. This work emphasises the potential of (MAGeI3) as a productive and eco-friendly component for tandem solar cells.

Evaluation of Transmitted X-ray Spectrum, Lead Equivalent, and Uniformity of Radiation Protective Clothing Made of Lead-containing and Lead-free Materials

The purpose of this study was to evaluate the protective performance of several new radiation-protective clothing and to clarify issues of quality control. The composition of the shielding elements was analyzed using X-ray fluorescence analysis, and the energy spectrum of transmitted X-rays was measured. Furthermore, the lead equivalent and uniformity were measured from the transmitted X-ray doses according to Japanese industrial standards (JIS). Uniformity was evaluated by transmitting X-ray images of each radiation protective clothing in addition to the conventional method. The energy spectrum showed K-absorption edges of lead, bismuth, tin, etc., which were detected in the composition analysis. The multi-layered protective material maintained higher shielding ability at high tube voltages. In addition, X-ray images of the radiation-protective clothing showed uneven density and dots, and the differences in uniformity measurement methods and points that didn't meet the required shielding capacity were seen. The current JIS does not allow accurate evaluation of the lead equivalent and uniformity, so visual evaluation of X-ray images is important. It is necessary to establish standardized standards for quality control performed by each facility.

Review of Piezoelectric Properties and Power Output of PVDF and Copolymer-Based Piezoelectric Nanogenerators.

The highest energy conversion efficiencies are typically shown by lead-containing piezoelectric materials, but the harmful environmental impacts of lead and its toxicity limit future use. At the bulk scale, lead-based piezoelectric materials have significantly higher piezoelectric properties when compared to lead-free piezoelectric materials. However, at the nanoscale, the piezoelectric properties of lead-free piezoelectric material can be significantly larger than the bulk scale. The piezoelectric properties of Poly(vinylidene fluoride) (PVDF) and Poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) lead-free piezoelectric nanomaterials are reviewed and their suitability for use in piezoelectric nanogenerators (PENGs) is determined. The impact of different PVDF/PVDF-TrFE composite structures on power output is explained. Strategies to improve the power output are given. Overall, this review finds that PVDF/PVDF-TrFE can have significantly increased piezoelectric properties at the nanoscale. However, these values are still lower than lead-free ceramics at the nanoscale. If the sole goal in developing a lead-free PENG is to maximize output power, lead-free ceramics at the nanoscale should be considered. However, lead-free ceramics are brittle, and thus encapsulation of lead-free ceramics in PVDF is a way to increase the flexibility of these PENGs. PVDF/PVDF-TrFE offers the advantage of being nontoxic and biocompatible, which is useful for many applications.

Assessment of the Attenuation Properties of Commercial Lead-Free Radiation-Shielding Composite Materials Against Medical X-rays

Six commercial, lead-free, radiation protective materials were tested for their attenuation across a range of X-ray energies used in medical diagnostic imaging and interventional radiology. While all the tested materials showed the specified attenuation at the X-ray energy claimed by their manufacturers, only two of the materials showed satisfactory attenuation in an extended range of medical X-ray energies (generated in X-ray tubes with voltages between 50 and 150 kV). The lead-free materials are lighter than the lead-containing materials, which is very important for those wearing the radiation protective garments for an extended time; however, the main focus in the promotion of radiation-shielding materials should still be on their attenuation efficacy against both the primary and the scattered X-rays present in medical environments. The end users should be informed on the material attenuation in an extended energy range, especially in the range where scatter radiation occurs, and not just about the peak material attenuation performance at energies where the X-rays are generated. Scatter radiation is the main reason for the occupational radiation exposure of medical personnel, who should have the whole picture about the shielding ability of the protective garments that they strongly rely on.

BaZrO3-modified (K,Na)NbO3-based lead-free piezoceramics: Enhanced electrical properties and high fatigue resistance

As legislative restrictions on the use of hazardous lead-containing materials are approaching and the demand for environmentally-benign piezoelectric materials continues to grow, there is an urgent need for viable lead-free piezoelectric alternatives. (K,Na)NbO3 (KNN)-based ceramics are environmentally-friendly, however, their piezoelectric properties still fall short of those of commercial lead-based ceramics. Herein, we report an alternative KNN material with the composition of (100-x)(K0.49Na0.49Li0.02)(Nb0.8Ta0.2)O3-xBaZrO3 + 2 wt % MnO ceramics prepared by a conventional solid-reaction approach. The addition of BaZrO3 produces finer domains and thus improves the piezoelectric and dielectric properties. MnO acts as sintering aid to reduce alkaline elements volatilization by lowering the sintering temperature. The mitigated volatilization of alkaline elements significantly reduces the concentration of oxygen vacancies, and thus contributes to enhanced piezoelectric properties. An optimal normalized strain (d33*) up to 476 pm/V at room temperature with a low driving electric field of 1.5 kV/mm is achieved at x = 4. More encouragingly, the ceramics also possess excellent temperature stability and fatigue resistance.

Synthesis, Structure, and Characterizations of a Heterobimetallic Heptanuclear Complex [Pb2Co5(acac)14

An unusual heterobimetallic volatile compound [Pb2Co5(acac)14] was synthesized by the gas phase/solid-state technique. The preparation can be readily scaled up using the solution approach. X-ray powder diffraction, ICP-OES analysis, and DART mass spectrometry were engaged to confirm the composition and purity of heterobimetallic complex. The composition is unique among the large family of lead(tin): transition metal = 2:1, 1:1, and 1:2 β-diketonates compounds that are mostly represented by coordination polymers. The molecular structure of the complex was elucidated by synchrotron single crystal X-ray diffraction to reveal the unique heptanuclear moiety {Co(acac)2[Pb(acac)2-Co(acac)2-Co(acac)2]2} built upon bridging interactions of acetylacetonate oxygens to neighboring metal centers that bring their coordination numbers to six. The appearance of unique heptanuclear assembly can be attributed to the fact that the [Co(acac)2] units feature both cis- and trans-bis-bridging modes, making the polynuclear moiety rather flexible. This type of octahedral coordination is relatively unique among known lead(tin)-3d transition metal β-diketonates. Due to the high-volatility, [Pb2Co5(acac)14] can be potentially applied as a MOCVD precursor for the low-temperature preparation of lead-containing functional materials.

Doping modification in lead-free piezoelectric ceramics

Piezoelectric ceramics are functional information ceramic materials that can convert mechanical and electrical energy into each other. They are widely used in high-tech fields, such as the electronics industry, machinery, and aerospace. Currently, Pb(ZrTi)O3 (PZT) piezoelectric materials are most commonly used, but the main component, PbO, is toxic and volatile during production and manufacturing, thus causing certain damage to human health and the environment. Therefore, research on green and environmentally friendly lead-free piezoelectric materials has been attracting much attention. This paper will therefore present two lead-free piezoelectric ceramics that have the potential to replace PZT-based lead-containing piezoelectric materials: Potassium Sodium Niobate (KNN)-based piezoelectric ceramics and Bismuth Sodium Titanate (BNT)-based lead-free piezoelectric ceramics. The piezoelectric constants of lead-free piezoelectric ceramics represented by systems such as KNN and BNT are now comparable to those of lead-containing piezoelectric ceramics and are gradually replacing traditional lead-based piezoelectric ceramics in fields such as ultrasonic atomization and hydroacoustic energy transfer.

Comparison of the radiation protection effect of different radiation protection aprons made of different materials

ObjectiveThe objective of this study is to examine the performance of new generation protection aprons as alternative to conventional lead aprons regarding their radiation protection effectiveness. Method and materialsRadiation protection aprons made of lead-containing and lead-free materials from a total of seven companies were compared. Furthermore, different lead equivalent values of 0.25, 0.35 and 0.5 mm were compared. For quantitative assessment, radiation attenuation was determined with increasing voltage in steps of 20 kV from 70 kV up to 130 kV. ResultsNew generation aprons and conventional protection lead aprons showed a similar shielding performance at lower tube voltages below 90 kVp. When tube voltage was increased above 90 kVp, significant (p < 0.05) differences between the three apron types were observed, with conventional lead material as best shielding performer over lead composite and lead-free aprons. ConclusionWe observed a similar radiation protection performance between conventional lead aprons and new generation aprons at low intensity radiation workplaces, with lead aprons being dominant for all energies. Only new generation aprons of 0.5 mm thickness would adequately replace 0.25 and 0.35 mm conventional lead aprons. For healthy radiation protection, the possibility of using weight-reduced X-ray aprons is very limited.

In Situ Crystallization of the Inorganic Lead-Free Halide Double Perovskite Cs2AgBiBr6 via Spray-Drying

Nontoxic, all-inorganic perovskite light absorbers have received a great deal of attention in recent years due to their potential to replace lead-containing perovskite materials in photovoltaics. Herein, the synthesis of the lead-free double perovskite Cs2AgBiBr6 as a powder, obtained via spray-drying, is reported to be capable of paving the way toward large scale production. Upon drying of the atomized precursor solution during spray-drying, the double-perovskite phase forms by in situ crystallization. The product that is obtained from spray-drying is compared to the one that is obtained from the so-called solution cooling method, which is often used for the absorber synthesis before dissolving the double perovskite powder for the thin film deposition. The absorber powder gained from the solution cooling method sets the benchmark for the spray-dried absorber powder. XRD and Raman analyses confirm the phase purity of the double perovskite, whereas UV–Vis spectroscopy confirms the desired bandgap. Furthermore, the absorber powders from both synthesis methods are successfully used to deposit and integrate absorber films in single-junction perovskite solar cells. Besides being introduced as an alternative synthesis route for the preparation of double perovskite absorber as dry powders independently from being applied onto a given substrate, the superior advantages of spray-drying compared to the conventional synthesis of the perovskite absorber via the solution cooling method are outlined: Spray-drying not only enables the synthesis of large amounts of perovskite absorber powders but also discards the usage of precarious solvents like concentrated hydrobromic acid and thus eliminates the need for extensive safety precautions. Hence, spray-drying may help the perovskite technology take the next step toward large-scale production and commercialization.

Review of Zinc Oxide Piezoelectric Nanogenerators: Piezoelectric Properties, Composite Structures and Power Output.

Lead-containing piezoelectric materials typically show the highest energy conversion efficiencies, but due to their toxicity they will be limited in future applications. In their bulk form, the piezoelectric properties of lead-free piezoelectric materials are significantly lower than lead-containing materials. However, the piezoelectric properties of lead-free piezoelectric materials at the nano scale can be significantly larger than the bulk scale. This review looks at the suitability of ZnO nanostructures as candidate lead-free piezoelectric materials for use in piezoelectric nanogenerators (PENGs) based on their piezoelectric properties. Of the papers reviewed, Neodymium-doped ZnO nanorods (NRs) have a comparable piezoelectric strain constant to bulk lead-based piezoelectric materials and hence are good candidates for PENGs. Piezoelectric energy harvesters typically have low power outputs and an improvement in their power density is needed. This review systematically reviews the different composite structures of ZnO PENGs to determine the effect of composite structure on power output. State-of-the-art techniques to increase the power output of PENGs are presented. Of the PENGs reviewed, the highest power output belonged to a vertically aligned ZnO nanowire (NWs) PENG (1-3 nanowire composite) with a power output of 45.87 μW/cm2 under finger tapping. Future directions of research and challenges are discussed.

Research on Preparation and Progress of Two-Dimensional Perovskite Solar Cells

Two-dimensional perovskite solar cells are considered as the most promising new type of solar cells due to their unique advantages such as strong spectral absorption, low cost, adjustable composition, excellent structure, excellent photoelectric characteristics and simple preparation through various processes. This paper will briefly introduce the structure and principle of two-dimensional perovskite solar cells, and introduce the research progress of top electrode materials in detail, including improving the preparation method of metal top electrode materials, repairing and introducing buffer layer and cathode intermediate layer for interface modification. High-performance perovskite solar cells use lead-containing perovskite materials as the light absorbing layer. Even if the device packaging process is perfect, lead-based perovskite materials still have the possibility of causing pollution to the environment, especially when the battery is damaged or the failed solar cells are improperly recycled. Therefore, in this paper, we can obtain high-quality perovskite films by improving the preparation process, solvent engineering and annealing engineering.

Development of Rectangular Vibration Isolators with Double Core Systems for Structures

One of the best techniques for isolating structures from the ground is the seismic isolation technique. Nowadays, square and circular base isolators are the most frequently employed shapes. Nevertheless, these configurations are not applicable for the wall-like structures; since the applied loads are not distributed in a way that provides a uniform support condition along the shear walls. To address this issue, attempts were made to develop novel rectangular isolators with lead/rubber cores. A total of five large-scale rectangular isolators were experimentally tested and subsequently subjected to finite element analysis. A rectangular seismic isolator having double lead cores was proposed to improve its effectiveness. Exposure to lead-containing materials has been shown to have poisonous effects on both the human health and environment. To avoid this, an isolator having double rubber cores was developed. Moreover, the rubber cores are wrapped with one layer of CFRP sheet and stainless steel tube to enhance the damping ratio of the rectangular isolators. Thereafter, the novel isolators were implemented in a 10-storey tunnel-form building using nonlinear dynamic analyses. The seismic performance of the buildings was then studied by conducting Incremental Dynamic Analyses. The experimental outcomes demonstrated that confining the rubber cores by stainless steel tube and CFRP sheet increased the energy absorption along the length of the isolators by 15 and 7%, respectively. Moreover, the damping ratios of the rectangular isolator with double lead cores have also increased by 36 and 47% along its length and width, respectively.

Oxidation of iodide by PbO2, the major lead pipe corrosion product: Kinetics, mechanism and formation of toxic iodinated disinfection by-products

Lead oxide (PbO2) formed by the oxidation of lead pipes and lead-containing plumbing materials is an important corrosion product in some drinking water distribution systems. Under certain conditions it acts as an oxidant, and we report here the effects of pH on the oxidation of I¯ by PbO2, which leads to the formation of iodine (I2) and iodate (IO3¯) as well as dissolution of Pb2+. Oxidation of I¯ by PbO2 is a multi-step pH-dependent reaction, the rate of which can be expressed as: R = 6.92 × 109 × [SA]0.67 × [I¯]2.19 × [H+]0.59 (where SA is the PbO2 surface area). I2 was the major intermediate product formed along with some HOI, and was then further oxidized to IO3¯. Based on these results, a kinetic model was developed to simulate the evolution of I¯, I2 and IO3¯ in the PbO2/I¯ reaction system. In addition, the formation of iodinated disinfection by-products (I-DBPs) in the PbO2/I¯/NOM system was evaluated under different water quality conditions, and was found to be influenced by the form of the lead corrosion products in the order: Pb3O4 > PbO2 > Pb(CO3)2(OH)2 > PbCO3. Iodoform and monoiodoacetic acid were identified as the main I-DBPs, and their formation decreased with increasing pH. It is concluded that oxidation of I¯ by lead oxides in water distribution pipes probably contributes to the formation of I-DBPs as well as Pb2+ in tap water.

Experimentelle Untersuchungen zum Einlaufverhalten bleifreier Sondermessinglegierungen

n tribological systems with high loads, leaded special brasses are preferably used because of their excellent wear properties. Axial piston pumps and motors are a good example of such systems. In order to be able to dispense with lead-containing materials in the future, alternative materials are being tested. The result of this development are three new lead-free special brass materials presented in this article. For these, the effect Abstract of surface roughness (fine/coarse) and the manufacturing process (fine grinding + vibratory grinding/ lapping + vibratory grinding) on the running-in behavior was investigated. The specifications for this are based on experience with the lead-containing reference material CuZn40Al2Mn2Si.

Characterization of Lead-containing Materials and Particles in Japanese House Dust Samples by Micro-XRF

Characterization of Lead-containing Materials and Particles in Japanese House Dust Samples by Micro-XRF

Analysis of Chemical Composition for Sasanian and Parthian Artwork Found in Various Region of Garmian Areas with Micro-XRF and P-XRF

The objectives of this paper are to use micro-X-ray fluorescence spectrometry (μ-XRF) and portable X-ray fluorescence spectrometry to specify the quality and element percent content of Sasanian and Parthian artwork samples: glasses, metals, and ceramics found in various regions of the Garmian area to determine and characterize the element and material compositions of the studied samples. The metallic models (L, M) are made of iron, (O) brass, (N.R) bronze, and (W, Y) silver, according to our findings. Soda ash makes up the majority of the glass samples (Si, Na, Ca&gt;1%, MgO, K2O&gt;1%). Sample J might be soda-lime glass because of the low Mg and K content (&lt;1% MgO, &lt;1% K2O). Six of the elements tested in the ceramic samples (Cl, Co, As, Mo, W, Bi) were not measurable (&lt;LOD). The origination of the samples is also of importance, in addition to the material composition. As a result, lead isotope analyses on the samples will be performed to assess the source of lead and lead-containing raw materials. The next measurement campaign, on the other hand, has yet to be arranged and can only be carried out with a bigger number of samples on hand.

Pollution sources identification, health, and radiological risk assessment of naturally occurring radioisotopes and heavy metals in waste dumpsites in Ijebu-Ode, Ogun State, Southwest Nigeria

This study evaluates human health, pollution, and radiological risk assessment of potentially toxic metals (PTMs) (Pb, Cd, Cr, Ni, and Zn), radioisotopes (238U, 232Th, and 40K) and its associated radiological indices from dumpsite soils in Ogun State, Nigeria, using a calibrated atomic absorption spectrophotometer (AAS) and highly shielded γ-ray spectrometry using NaI(TI) detector. Fourier transform infrared spectrometer (FTIR) complemented by X-ray diffraction (XRD) techniques were used to evaluate the mineralogical composition of the soils. Multivariate statistical analysis was used to apportion the source of PTMs and the radioisotopes. The mean concentration of Pb, Cd, Cr, Ni, and Zn obtained were 22.35, 17.95, 20.83, 19.02, and 75.88 mg kg−1, respectively. The activity concentrations of 238U, 232Th, and 40K ranged from 49.71 ± 16.3 − 314.15 ± 55.2, BDL − 87.54 ± 7.38, and BDL − 3721.3 ± 231.6 Bqkg−1, respectively. The values obtained were above the global average value in most of the samples. According to the four-pollution and ecological risk assessment model, the dumpsite soils are strongly to low polluted and enriched with toxic metals in the order Zn > Cr > Pb > Ni > Cd. The estimated carcinogenic risk of the three carcinogenic PTMs for children and adults were higher than the acceptable limit (1 × 10−6). The results of the PCA and HCA results are consistent with the correlation coefficient analysis which showed that mixed natural, anthropogenic and lithogenic sources mainly from aggregation of lead-containing materials in the waste on the dumpsite, vehicular emission and industrial discharges are the main sources of Pb, Ni, and Cd in the three studied dumpsites. Thus, dumpsite soil poses great threat to health, increased pollution and enhances the radiological risk to the general population via human multiple exposure routes.