PbO Content Research Articles

Assessment of X-ray shielding properties of polystyrene incorporated with different nano-sizes of PbO.

PbO (lead oxide) particles with different sizes were incorporated into polystyrene (PS) with various weight fractions (0, 10, 15, 25, 35%). These novel PS/PbO nano-composites were produced by roll mill mixing and compressing molding techniques and then investigated for radiation attenuation of X-rays (N-series/ISO 4037) typically used in radiology. Properties of the PbO particles were studied by X-ray diffraction (XRD). Filler dispersion and elemental composition of the prepared nano-composites were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), revealing better filler distribution and fewer agglomerations with smaller PbO particle size. Linear and mass attenuation coefficients (μ and μm), total molecular and atomic cross-sections (σmol and σatm), as well as effective atomic number and electron density (Zeff and Neff), were calculated for the energy range N40 to N200. The influence of PbO weight percentage on the enhancement of the shielding parameters of the nano-composites was expected; however, the effect of PbO particle size was surprising. Linear and mass attenuation coefficients for PS/PbO composites increased gradually with increasing PbO concentrations, and composites with a small size of nanoparticles showed best performance. In addition, increasing PbO concentration raised the effective atomic number Zeff of the composite. Hence, the electron density Neff increased, which provided a higher total interaction cross-section of X-rays with the composites. Maximum radiation shielding was observed for PS/PbO(B). It is concluded that this material might be used in developping low-cost and lightweight X-ray shielding to be used in radiology.

Efficiency of Electrochemical Methods of Purification and Control over the Oxide Concentration in Halide Melts: PbCl2

The purification of molten salts from admixtures as well as the effective control of admixture concentration has attracted researchers’ interests. In the present paper, the possibility of the electrochemical purification of PbCl2 from PbO and the effective control over the oxide ions concentration in molten PbCl2 is studied at the temperature of 520 °C. The PbCl2 melt with the initial addition of 0.5 wt% of PbO was used as a molten salt sample. The method of potentiostatic electrolysis was used to remove the oxide additions from the melt; the linear and square-wave voltammetry dependencies were recorded, and the melt samples were taken for analysis. Based both on the results of the electrochemical measurements and the analysis of oxygen concentration in the electrolyte, we built linear empirical dependencies of the anode peak current of the oxidation of oxygen-containing electroactive anions on the PbO concentration in the studied melt. We demonstrated that the obtained dependencies may be used for direct electrochemical nondestructive in-situ control over the concentration of PbO dissolved in the PbCl2 melt containing up to 0.5 wt% of PbO. The deep electrochemical purification of the chloride PbCl2 melt from molten oxide (up to 0.044 wt% PbO or to 0.007 wt% of oxygen) was achieved by the potentiostatic electrolysis.

Gamma Attenuation and Mechanical Characteristics of a Lead/NBR/SBR Rubber Composite with Black Nanocarbon Reinforcement

In this work, black nanocarbon-loaded 0–100 parts-per-hundred (phr) PbO-filled acrylonitrile butadiene rubber (NBR)/styrene-butadiene rubber (SBR) blend composites were prepared by using an ordinary standard rubber mixer. Both mechanical and gamma attenuation properties of the prepared samples were investigated. Maximum tensile strength and elongation at break were obtained at 40 phr PbO concentration. The obtained values for the mass attenuation coefficient with the increased PbO concentration from 0–100 phr ranged from 0.12–0.22 cm2/g at 0.239 MeV. Scanning electron microscope (SEM) with the elemental mapping analysis results showed high homogeneity at 40 phr of the prepared rubber composites, with some areas of elemental agglomeration at a high concentration of lead oxide. The obtained results highly recommend the use of the prepared nanocarbon-reinforced PbO/NBR/SBR blend compared to those previously used as personal protective equipment in radiation-shielding applications.

Improvement of etching ability of lead-free glass frits by compositing low content PbO nanoparticles and its effect on metallization contact of solar cells

Numerous research studies have been conducted on lead-free glass frits for crystalline silicon solar cells due to the high toxicity of Pb. However, lead-free glass frits have poor metallization performance. The excellent performance of PbO in glass frits cannot be completely replaced by other compounds. In this study, in order to reduce the PbO content in glass frits while keeping its excellent properties, a method for the preparation of low-content lead oxide composited glass frits was established. High temperature microscopy revealed that the temperature coefficients of the glass frit decreased as the lead content increased. FT-IR and Raman spectroscopy results indicated that the main structure of the glass remain intact under compositing PbO. The specific surface area of the glass frit increased after compositing PbO. The etching ability of lead-free glass frit to silicon wafer was improved. After the glass frit was prepared into silver paste, it found that the silver electrode formed excellent metallized contact with silicon and more silver microcrystals were deposited on the silicon surface to increase the conductive path.

PbO-TeO2-MgO-Na2O-B2O3 glasses: Optical properties and gamma ray shielding behaviour studies using the Monte Carlo simulation

Melt quenching is used to make the PbO-TeO2-MgO-Na2O-B2O3 glasses. As lead concentration rises, so does density rise from 3.283 to 3.923 g/cm3. The indirect band gap values decrease from 3.262 to 3.111 eV as lead oxide increases. The refractive index (n), optical dielectric constant, and dielectric constant (ε) increase from 2.329 to 2.368, 4.428 – 4.606, and 5.428 – 5.606 with the increase in lead content. The metallization value of all the samples is less than unity which confirms the non-metallic nature of all samples. The partial replacement of B2O3 by PbO compounds affects also the shielding characteristics. The Monte Carlo simulation for the gamma-ray shielding parameters depicts that the linear attenuation coefficient (LAC) of the fabricated samples increases gradually with rising the B2O3 substitution ratio. For example, at 244 keV, the linear attenuation coefficient enhances by 51% with increasing PbO content. The increase in LAC was associated with a significant decrease in the half-value thickness, thickness equivalent, and transmission factor while the radiation protection efficiency of the fabricated samples was enhanced. Therefore, fabricated glasses are considered a better choice to be used in the radiation zones.

Assessment of mechanical and gamma ray shielding capability of highly dense PbO-TeO2-CdO glasses

The highly dense PbO-TeO2-CdO glasses have been fabricated by the melt quenching procedure. The prepared samples are light yellow in colour and are highly transparent. The density of the samples is very high and it lies in the range of 5.576–6.082 g/cm3. The molar volume is showing downtrend from 35.488 to 33.705 cm3 accounting towards the compactness of the samples with addition of PbO. Oxygen packing density increases from 30.996 to 32.637 whereas the oxygen molar volume is decreasing from 32.262 to 30.641 cm3 mol−1 with increase in PbO content. As PbO grows, E's modulus rises from 18.517 to 19.368 GPa, B's from 6.903 to 7.705 GPa, G's from 9.504 to 9.662 GPa, and L's from 19575 to 20.558 GPa. We used the Phy-X software to estimate the radiation shielding properties for the prepared glasses in a wide energy range of 0.015–15 MeV. We reported an enhancement in the mass attenuation coefficient (MAC) values when the PbO level increases from 70 to 77.5 mol %, this he highest MAC is found for PTC4, while the lowest MAC is reported for PTC1 sample. The photon energy has an impact on Linear attenuation coefficient (LAC) and the Greatest values of this parameter is reported at 0.015 MeV and equalling 501.64, 521.84, 549.53 and 569.17 cm−1 for the PTC1 to PTC4 glasses. In contrast, the lowest LAC is reported at 15 MeV (in the range of 0.283–0.313 cm−1). According to the LAC, the studied samples are able to attenuate more photons in the low energy region. The effective atomic number (Zeff) is also evaluated and similar to LAC, we found that the Zeff is increased due to the addition of PbO. From the results of different shielding factors, the inclusion of PbO alters the radiation attenuation performance.

The effect of Bi2O3/PbO substitution on physical, optical, structural, and gamma shielding properties of boro-tellurite glasses

Boro-tellurite glasses with molar compositions 60TeO2–20B2O3-(20-x)Bi2O3-xPbO, where x = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 mol% were fabricated using a standard melt quenching technique and studied in term of their physical, optical, structural and gamma shielding properties. As PbO concentration increases from 0 to 10 mol% (Bi2O3 decreases), the density and molar volume of the present samples decrease from 6.08 to 5.93 gr/cm3 and 33.37 to 30.27 cm3/mol, respectively. The optical packing density increases from 71.91 to 72.67% as PbO is added to the network to substitute Bi2O3. With the increase of PbO concentration, the refractive index, molar refractivity, and ionic polarizability decrease from 1.9137 to 1.8306, 18.531 to 16.884 cm3, and 7.3534 to 6.7000 Å3, respectively. The percentage of [TeO3] (tp) and [TeO3+1] polyhedra in the glass network increase with the rise of PbO concentration. The gamma radiation shielding features were analyzed theoretically using Phy-X PSD software with photon energies varied between 0.015 and 15 MeV. For all glasses, the highest linear attenuation coefficient (LAC) values are observed at 0.015 MeV while the lowest values are observed around 5 MeV, a turning point at which pair production starts to dominate the gamma photon-electron interaction. At all photon energies, the LAC values decrease with the increase in PbO concentration (the decrease in Bi2O3). The LAC values at 0.015 MeV vary from 413.2183 to 12.4962 cm−1. At low photon energies (0.015–0.04 MeV), this compositional dependence is high. Above 0.04 MeV, this dependence is low. This LAC result suggests that adding Bi2O3 to the glasses is favorable for gamma shielding material as compared to PbO.

An archaeometric assessment study of Seljuk period glazed tiles from Kılıçarslan Square (Konya, Turkey)

This study presents archaeometric analyses of glazed tiles produced with the cut-mosaic technique to reveal information about the Anatolian Seljuk period’s architecture and ceramic technology. The Persian Seljuk artists also used the same technique. For this purpose, physical, chemical, thermal, mineralogical, microstructural, and molecular analyses were carried out on the tiles from the Seljuk period unearthed in the Kılıçarslan Square excavation in Konya, the capital of the Anatolian Seljuk State from the twelfth-century to the beginning of the fourteenth-century. SEM, XRD, and Heat Microscopy analyses showed that the Seljuk period tiles were not fired at high temperatures like today’s tiles and were probably fired at temperatures below 1100 °C. WD-XRF analyses revealed that the glazes are classified into two categories, one being alkali varying the content of Na2O + K2O between 13 and 16 wt% (PbO between 0.5 and 2 wt%) and the other being lead-alkali type in which PbO content varies between 13 and 15 wt% and alkali content 10–14 wt%. The cobalt content in the blue color is around 0.2 wt%, and copper content in the turquoise-colored samples varies between 2.9 and 4.4 wt% depending on the lightness and darkness of the color (higher amount for tile 1 and tile 3, which are darker than the others). The brown color is obtained by the presence of MnO (3.3 wt%). Raman analysis showed that the difference in sintering temperature caused the color tone difference in Seljuk period tiles, and glazes were formed in the range of 800–1000 °C depending on the Ip values.

Protective efficacy of holed and aging PBO-pyrethroid synergist-treated nets on malaria infection prevalence in north-western Tanzania.

Two billion pyrethroid long-lasting insecticidal nets (LLINs) have been distributed since 2004 for malaria prevention in Sub-Saharan Africa. Current malaria control strategies rely on an assumed effective 3-year lifespan for LLINs. PBO synergist LLINs are a newly recommended class of net but there is limited information on their life span and long-term protective efficacy in communities. To assess their operational survival, a cohort of 390 PBO LLINs (Olyset Plus) and 367 standard pyrethroid LLIN (Olyset net) from 396 households were followed for 36 months in Western Tanzania. To assess the association between the condition of the LLIN and malaria infection, nets from at least 480 randomly selected households were assessed during malaria prevalence cross-sectional surveys at 4, 9, 16, 21, 28, and 33 months post-distribution. Information on the presence and condition of nets, and demographic information from the household, were collected to evaluate factors influencing net durability. After 3 years less than 17% of nets distributed still remained in the households. The fabric condition was not associated with malaria infection in either type of net. The difference between the net types was highest when nets were between 1-2 years old, when PBO nets appeared to be similarly protective as nets less than a year old, whereas standard nets were considerably less protective as they aged, regardless of fabric condition. There was no statistical difference in the estimated median functional survival time between net types with 1.6 years (95% CI 1.38-1.87) for PBO LLIN and 1.9 years (95% CI 1.67-2.06) for standard LLINs. After 3 years, there was a loss of 55% of permethrin (pyrethroid) content for both nets, and 97% of PBO content was lost in PBO LLIN. These results highlight that functional survival is less than the recommended 3 years for both net types. However, even as the nets age, the PBO nets remained more protective than standard nets, regardless of their condition.

Structural analysis and characterization of lead oxide

In this study, different nano sizes of lead oxide particles are prepared using high-speed planetary ball milling over a range of grinding times (15, 30, 60 and 120 minutes). The characterization of the prepared nanoparticles is carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier Transform-Infrared spectroscopy (FTIR). The XRD pattern reveals a phase transition from β-PbO to α-PbO with increasing the milling time. The PbO particles milled for 30 and 60 minutes and termed PbO(A) and PbO(B), respectively, are chosen for this research as they display less agglomeration and achieve nano sizes of 78 and 52 nm, respectively. The following stage utilizes PbO(Bulk), PbO(A) and PbO(B) as fillers and incorporates them independently into PS with a concentration of 10, 15, 25 and 35 wt % using roll mill mixing and compression molding techniques to create a novel polystyrene composite (PS/PbO). PS/PbO composites were then characterized by XRD, which shows a decrease in the phase percentage of PS to α-PbO with increasing PbO content. Extensive research of thermal characteristics employing thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) enables the evaluation of decomposition rates and activation energies. The analysis reveals that the addition of bulk and nano PbO particles shifts Tini and T50% to higher temperatures, and reduces the decomposition rate as well as the activation energy. This means that the thermal stability of PS is increased, especially using a small PbO nano size. This study emphasizes the role of particle size in enhancing the thermal properties of polystyrene, allowing it to withstand elevated temperatures in applications such as coating, insulation and radiation shielding.

Experimental and theoretical investigation on physical, structure and protection features of TeO2–B2O3 glass doped with PbO in terms of gamma, neutron, proton and alpha particles

Glass series of composition 70TeO2- (30-x)B2O3- xPbO (where x = 2, 6, 10, 14 and 20 mol%) is prepared using melt-quenching technique. The glass structure was investigated by X-ray diffraction (XRD). Manufactured glass density, molar volume and Fourier transform infrared spectroscopy (FTIR) were measured. Shielding parameters against gamma-rays including, linear attenuation coefficient (μ), mass attenuation coefficients (μm), half-value layer (HVL) and mean free path (λ) were measured experimentally at energies of 0.664, 1.177 and 1.334 MeV using Cs137 and Co60 point sources and NaI(TL) scintillation detector. The measured parameters were compared with those calculated using XCOM program with a good agreement between them. To fully comprehend the shielding efficiency of the prepared glasses, several shielding parameters including, μm, HVL, effective atomic number (Zeff), electron density (Nel), equivalent atomic number (Zeq), exposure and energy absorption buildup factors (EBF & EABF), radiation protection efficiency (RPE) and kerma relative to air (Ka), were evaluated in the photon energy range 0.015–15 MeV and compared with some materials that commonly used as gamma-ray shielding. The findings demonstrate the viability of employing the current glass composition as an effective agent for gamma-ray shielding and fully protection (100%) for x-ray. The macroscopic effective removal cross section (ΣR) of the prepared glasses were calculated and compared with those of frequently used neutron shielding materials. Finally, the mass stopping power (MSP) and projected range (PR) values of proton (H1) and alpha particles (He+2) have been evaluated in the energy range 0.01–15 MeV. The results show that, increasing PbO content improves shielding characteristics. Among the examined samples, the S5 glass sample was found to be superior in terms of photon, neutron, proton and alpha particles protection. These results indicate that, the prepared glass samples are highly appropriate nuclear shielding material that can be used in many applications.

Radiation shielding and optical features for a PbO–BaO–B2O3 system

Glass compositions of xPbO-(40-x)BaO–60B2O3 system (0 ≤ x ≤ 40) have been prepared and investigated for their physical, optical, and radiation shielding properties. The optical spectra of the present system reveal UV–Vis absorption related to the presence of lead ions besides the unavoidable trace impurities within the raw materials. It is found that the density D increased and molar volume Vm decreased slowly with increasing PbO content which is attributed mainly to the higher molecular weight of PbO than BaO. Eg, n and EU remain almost constant with increasing PbO content which implies little change in the fraction of NBOs. The molar refraction decreases slightly from 16.2 to 15.89 cm3, and there is mostly no change observed in the value of the metallization criterion. Within an energy photon range of 0.015–15 MeV, Monte Carlo simulation package (FLUKA) and NISTXCOM enabled evaluation of prepared glasses' radiation shielding capability. This investigation revealed that as the PbO content of a glass network increases from 0 to 40 mol percent, the gamma shielding properties of the glass samples improve. The results also indicated that the values of both FLUKA and NIST XCOM are close, indicating the accuracy of the obtained results. In the half-value layer (T0.5) experiments, we discovered that a layer of relatively thin thickness could be employed to diminish the intensity of low-energy photons. Higher energy requires a thicker layer in order to minimize the number of photons that can pass through the glass.

Gadolinium-based ceramics doped with lead oxide for γ-ray shielding

In this study, gadolinium-based ceramics (GdBa2Cu3Oy) doped with lead oxide (PbO) were prepared using the solid-state reaction approach. The effect of different PbO concentrations (x = 0.0, 2.0, 5.0, 10.0 wt%) on the structure, physical and optical peculiarities of GdBa2Cu3Oy lead oxide was investigated. The radiation attenuation characteristics were also estimated using Monte Carlo simulations. It was observed that the inclusion of PbO from 0.0 wt.% to 10.0 wt.% led to a significant change in the physical parameters of the prepared ceramics. The density of ceramics increased from 4.42 g/cm3 for x = 0.0 wt% to 4.53, 4.64, and 4.72 g/cm3 for x = 2.0, 5.0, and 10.0 wt%, respectively. The X-ray diffraction results showed that the pure GdBa2Cu3Oy ceramic was indexed as a polycrystalline orthorhombic phase. Some peaks related to BaPbO3 impurities were observed for the PbO-doped ceramics. The crystal size was found in the range of 21.1–41.18 nm, and the lattice strain was increased by adding PbO. The energy bandgap of the GdBa2Cu3Oy-doped PbO oxide was changed from 0.59 to 1.56 V with increasing PbO concentration up to 10.0 wt%. The prepared ceramics have shown good performance in radiation protection. The linear attenuation coefficient for the synthesized ceramic samples was examined utilizing the Monte Carlo N- particle transport code (MCNP), for the emitted gamma photons with energies varied in the interval extended from 0.15 to 15 MeV.

ErBaCuO/PbO ceramic composites: Synthesis, physical properties, and radiation shielding performance

The search for shielding materials against ionizing radiation is very important due to the harmful effect that these radiations cause on human health and the environment. In this work, new ceramic composites of ErBa2Cu3Ox/lead oxide (ErBaCuO/PbO) instead of pure lead are proposed and prepared to serve as promising alternative materials for gamma radiation protection. X-ray diffraction was used to examine the structural properties of the prepared ceramic composites. The analysis showed that all composites have an orthorhombic structure with Pmmm symmetry. The addition of PbO induced distortion of the crystal structure of the ErBCO system. The structural parameters including lattice constants and unit cell volume showed a great variability with the addition of PbO. The physical properties including the density and porosity of the prepared ceramic composites were also determined. It was found that the density values increased from 4510 kg/m3 for 0 wt% to 4640, 4750, 4800 kg/m3 for 2, 5, and 10 wt%, respectively, while the porosity reduced with increasing the PbO content. The Monte Carlo simulation was used to estimate the linear attenuation coefficients of the as-prepared ceramics at different energies of gamma-ray photons ranging from 0.059 to 1.408 MeV. Other shielding parameters were computed, including half-value thickness, transmission factor, and radiation protection efficiency. The results showed an improvement in radiation protection efficiency and a decrease in the transmission factor values with increasing the concentration of PbO. For example, the half-value thickness reduced from 1.949 to 1.832 cm while the radiation protection efficiency increased from 29.93 to 31.51%, at gamma-ray energy of 0.662 MeV, once the concentration of PbO was increased from 0 to 10 wt %, respectively.

Mass stopping power and nuclear shielding behavior of lead borate glasses: Influence of gamma irradiation on physical properties

Four glassy systems with dissimilar PbO ratios were synthesized by the melting method. Raman scattering was used to study the chemical bonds inside the glass structures and follow the chemical changes occurring inside their networks after using the glasses in a radiation field. The glass samples are based on several tetrahedral and triangular groups where in BO3 is predominant. The energy gap of each sample was calculated from two different equations extracted from absorption and transmission measurements as ETauc and ETrans, respectively. Also, chemical durability has been studied to show the stability of these glasses against acidic environmental effect and followed by SEM images. Our findings showed that radiation effect on the prepared samples did not cause significant variations of structural and optical characteristics, however, increasing PbO concentrations resulting in enhancement of several radiation attenuation competencies. This study presented a comprehensive study of the radiation shielding properties of lead borate glass by assessing the effectiveness of proton, electron, neutron, and gamma shielding. Mass stopping power (ψp) and projected range (PR) values were calculated for proton particles (H1) using SRIM Monte Carlo simulation code and its subroutine TRIM, which predicts the radiation damage and atomic displacements per atom (dpa), while the ESTAR program was used to calculate ψe and the continuous slowing down approximation (CSDA) range for electrons. Furthermore; the findings estimate the excess lifetime cancer risk% for radiation workers behind the glass shields. Also, the glass with the lowest PbO content has the highest ΣR value, whereas the sample with the highest PbO content has the highest MAC value of gamma rays.

Effect of PbO and B2O3 on the Physical, Structural, and Radiation Shielding Properties of PbO-TeO2-MgO-Na2O-B2O3 Glasses

The process of melt quenching is utilized in the preparation of the PbO-TeO2-MgO-Na2O-B2O3 glasses. The effect of PbO and B2O3 on the physical, structural, and radiation shielding properties of present glasses have been presented in this study. As the lead concentration rises, both the density and the molecular weight rise, climbing from 3.283 to 3.923 g/cm3 and from 105.638 to 128.675 g, respectively. The utilization of PbO as an alternative to B2O3 contributes to an increase in the overall number of at-oms, which in turn contributes to an increase in the molar volume. The XRD spectra show that the samples are amorphous. The different bending and stretching vibrations of the bonds present in the samples are shown by the FTIR spectra. The mass attenuation coefficient (MAC), linear attenuation coefficients (LAC), half-value layers (HVL), and effective atomic number (Zeff) were calculated using Phy-X software within the energy range 0.284–2.506 MeV. These obtained verdicts advocate that pre-pared Pb4 glass containing the highest concentration of PbO showed supreme shielding ability comparing the rest of the pre-pared glasses. According to these results, it can be said that PbO and B2O3 are the weighty additive composites for glass composition in the interest of radiation shielding.

Hydrothermal Uranium Mineralization in Umra, Udaipur District, Rajasthan, India: Inferences from Petrography, Mineral Chemistry and Sulfur Isotopic Studies

Abstract Uranium mineralization at Umra, Udaipur district, Rajasthan is hosted by carbon and siliceous phyllite (with minor calcareous components) of the Paleoproterozoic Aravalli Supergroup. The mineralized zone trends NE-SW to N-S, dipping 45-55° towards SE to E. Uraninite, coffinite and brannerite are the main uranium phases observed that occur in association with sulphides (pyrrhotite, pentlandite, gersdorffite, chalcopyrite and pyrite), magnetite and ilmenite. Uraninite is found to occur as veins and disseminated ultrafine grains. Colloform and botryoidal texture with shrinkage/ synaeresis cracks indicate the presence of pitchblende also, formed at relatively low-temperature. Textural features suggest remobilization of disseminated syngenetic and / or diagenetic uranium minerals during low-grade metamorphism and deformation. Textural features suggest multiple phases of sulphide mineralization also. Mineral chemical data indicate that uraninite and pitchblende are compositionally similar containing 80.09-87.17 wt.% UO2 (av. 84.45 wt.%) and 11.37-11.82 wt.% PbO (av. 11.58 wt.%) with negligible SiO2, CaO, TiO2, FeO, ThO2 and RE2O3. High U/Th ratio (>1000) in uraninite/ pitchblende indicates limited cationic substitution and therefore low temperature (<350°C) hydrothermal origin of mineralization. Chemical age, calculated on the basis of UO2, ThO2 and PbO concentration in uraninite, indicates the minimum age of mineralization is 956±12 Ma. S isotopic data of pyrite suggest syn-sedimentary or diagenetic origin by bacterial reduction of seawater or pore water sulphate under anoxic conditions (-24.7‰ to -16.2‰), as well as hydrothermal (-3.7‰ to +8.8‰) origin. Similarity of S isotopic composition of hydrothermal pyrite with that of pyrite (+5.2‰) from meta-basic rock indicates that a component of S has been derived from the associated basic/meta-basic rocks in the area. Signatures of multiple generations of uranium mineralization, and multiple episodes of deformation, metamorphism and hydrothermal alteration reveal a complex metallogenic history in Umra. Compositional details of uraninite and their occurrence in the form of veinlets in association with hydrothermal pyrite suggest dominantly epigenetic hydrothermal mineralization events coeval with deformations of the Aravalli sediments.

Properties and mechanism of amorphous lead aluminosilicate passivation layers used in semiconductor devices through molecular dynamic simulation

With the rapid development of the semiconductor industry, the glass passivation process is being optimized as an important process for the protection of electronic components. Lead aluminosilicate glasses, with a stable network structure, adjustable thermal expansion coefficient and high voltage resistance, are valuable for use in power devices such as diodes. In this work, the effects of PbO content on the expansion and thermal properties of lead aluminosilicate glasses were investigated by combining molecular dynamics simulations and experimental tests. The relationship between structural changes and performance is analyzed in detail, and the passivation mechanism of lead aluminosilicate glass for semiconductor devices is also elucidated. The results show that the thermal expansion coefficients of glass and silica wafers can match the glass composition with PbO contents of 15–25 mol%. The diffusion ability of Pb atoms in the network structure is also the lowest in this concentration range. The glass transition temperature (Tg) and fluidity at high temperature, both decrease with increasing PbO content. In addition, the glass powder was applied to MOS devices for electrical performance testing. It was found that when the PbO content was at 20 mol%, the glass passivation layer and the silicon wafer had tight interfacial contact after sintering. The interfacial defect density reached the minimum value (5.276 × 1010 cm−2eV−1) along with a high fixed charge density (2.124 × 1010 cm−2). In other words, the glass powder composed of 20PbO-4.8Al2O3-75.2SiO2 (mol%) can minimize the interfacial carrier compound, reduce the interfacial contact resistance and increase the current density to achieve a more desirable interfacial passivation effect in semiconductor devices.

Synthesis of lead oxide doped SmBa2Cu3Oy ceramic systems as efficient shields against γ radiations: Structure, radiation attenuating capacities, and optical features

Radiation has great significance in human life; it can be used in different fields such as agriculture, industry, medicine, and food sterilization. There are several methods to protect humans from gamma radiation; one of these methods is using shielding materials. Herein, ceramic SmBa2Cu3Oy materials doped with 0.0, 2.0, 5.0, and 10.0 wt% of lead oxide have been prepared and tested against gamma-ray. XRD analyses showed an orthorhombic structure of all ceramics with the presence of Pb-rich impurity in doped ceramics. The optical bandgap energy values were in the range of 1.54–162 eV. The Monte Carlo N-Particle transpose code was adopted to simulate the shielding parameters in the interval between 0.015 and 15 MeV. The shielding properties are enhanced by mixing SmBa2Cu3Oy with the PbO compound. The linear attenuation coefficient at 1.25 MeV increased from 0.219 cm−1 to 0.230 cm−1, with increasing the PbO concentration from 0.0 to 10.0 wt%, respectively.

Preparation, radiation shielding and mechanical characterization of PbO–TeO2–MgO–Na2O–B2O3 glasses

Borate glasses composed of PbO–TeO2–MgO–Na2O–B2O3 were prepared by melt-quenching technique. The radiation shielding and mechanical properties of this glass system were thoroughly investigated. The density of the glasses increases from 3.283 to 3.923 g/cm3 as the PbO content increases from 20 to 35 mol%. The mechanical properties are evaluated using the Makishima and Mackenzie model. The density and chemical composition of the samples are found to affect the mechanical properties. Furthermore, produced glasses' radiation shielding properties were evaluated by calculating the basic attenuation factors such as the mass/linear attenuation coefficients, half/tenth value layers, radiation shielding efficiency and lead equivalent thickness. These parameters were calculated for photon energies in the range of 15 keV-15 MeV using Phy-X software. We discussed the impact of PbO and B2O3 on the attenuation parameters of these glasses, and we found that these oxides affected the attenuation ability of the samples, especially at low energies. The mass attenuation coefficient for the prepared glasses has high values at 88 keV. The results for the different parameters demonstrated that the glass containing 35 mol % PbO has the best photon attenuation ability among other glasses. While, the sample with highest B2O3 content possesses the highest half value layer. The radiation shielding parameters for prepared glass system were compared with other materials.