Increasing PbO Content Research Articles

Structural, physical and thermal properties of lead germanate glasses

The effects of PbO concentration on the density, thermal and structural properties of xPbO–(100-x)GeO2 (x = 20 to 55 mol%) glasses were studied. Density of glasses increases linearly from 5.043 to 6.981(5) g·cm−3, while the glass transition temperature decreases drastically from 467 °C to 359 °C on increasing PbO concentration from 20 to 55 mol%. Neutron diffraction studies found that Ge-O co-ordination is in the range: 3.9–4.2(1), and there is a very weak germanate co-ordination anomaly at PbO concentration of 40 and 50 mol%. GeO4 are the dominant structural units with a small quantity of GeO3 and GeO5 but very little GeO6 in the glass network. Pb-O and OO co-ordination decreases with an increase in PbO mol% and are in the range of: 4.0–3.1(1) and 6.3–5.4(1) respectively. Raman studies indicate a decrease in Pb-O co-ordination with increase in PbO mol%, in good agreement with the neutron diffraction findings.

Investigation on the effect of ZnO/PbO exchange on Physical and Optical Properties of Tellurite Sodium Bismuth Zinc doped Lead Oxide Glasses

New tellurite glasses having compositions: 60TeO2-(35-x)ZnO-3Bi2O3-2Na2O-x PbO and 55TeO2-(41-x)ZnO-2Bi2O3-2Na2O-x PbO where x = 0 and 0.5 mol% were fabricated and characterised in order to study the effect of substitution of PbO by ZnO. Density measurement was carried out by applying Archimides principle, that is by using pycnometer. Refractive index measurement was carried out by applying Brewster angle method, at which the intensity change in transversed magnetic light (λ = 632.5 nm) was recorded. From the experiment it can be shown that the glass density increses with the increse of PbO concentration, for the first glasses it change from 5.71 to 5.74 gr/cm3 while for the later it change from 5.85 to 5.87 cm3. Their molar volumes, however, behave inversely. Refractive index change due to this compostional change behave in same manner as density, refractive index increses with the increase of PbO content. Refractive indexes of the first pair are 1.89 and 1.93, respectively, while the later are 1.88 and 1.95, rspetively. Based on these findings, each pairs is a potential candidate for fabricating fiber optic at which the lower index is for cladding material while the higher index for core material.

Influence of PbO content on the glass forming ability, crystallization, electrical, UV–Vis. and photoluminescence spectroscopy properties of LiF.PbO system

New glass samples were synthesized from the binary system LiF. PbO with different ratiosby the traditional melt-quenching technique. The corresponding glass-ceramics were formed by heat treating the prepared glasses. Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Transmission electron microscope (TEM) were employed to study the structure of the samples; while characterization of the glass and glass-ceramics were studied using photoluminescence (PL) spectral analysis, electrical, UV–Visible absorption, optical band gap and hardness measurements. The ability to form glass was increased with increase PbO content (1LiF:≥5PbO). Tetragonal and orthorhombic PbO, orthorhombic and monoclinic Pb2O3, α-PbF2 and traces of both Li4PbO4, PbO1.37 were crystallized under specific heat-treatment circumstances as identified by XRD analysis. The crystal size decreased with increasing the PbO content; it reaches ∼15 nm in case of 10 Pb. PL revealed concentration quenching in glass with 10 Pb, a red shift and enhancement of bands intensity were observed with decrease λex, increase heat-treatment temperature and increase PbO concentration. The UV–Visible absorption elucidated that the cutoff wavelength (λ) was shifted toward lower wavelength (blue shift) by increasing PbO content and the values of optical band gap energies recorded 2.69, 2.66 and 2.72 eV for LiF·5PbO, LiF·8PbO, and LiF·10PbO, respectively. The electrical properties recorded conductivity ∼1.2 × 10−6 S m−1 and dielectric constant ∼ 46.8. These characteristics suggests that, the prepared materials exhibited semiconducting and photoluminescence behavior nominated it to be utilized in solar cell applications.

Designing High-Density of PbO-Enriched Telluro-Borate Glasses for Improved Radiation Shielding: A Comprehensive Study of Attenuation Parameters

Several radiation shielding parameters for (75-x) B2O3−10TeO2−13SrCO3 −2ZnO-xPbO glasses were evaluated between 0.284 and 1.333 MeV. The PbO content in the glass has a positive relationship with the density of the glasses, leading to BTSZP0, the glass with no PbO, having the smallest density, while BTSZP5, which has 40 PbO mol%, has the greatest density. Radiation shielding parameters such as mass attenuation coefficients (MAC) and other related factors were computed, and relationships between PbO content, energy, and density are graphed. Linear attenuation coefficient (LAC) is reported and we evaluated the impact of density on the LAC values. By adding more PbO atoms, the density of the samples increased, leading to a higher LAC. The BTSZP0 sample has the highest HVL at all tested energies, with the BTSZP5 sample having the lowest HVL. Mean free path (MFP) has an inverse relationship with the density of each sample but increases with greater incoming photon energy. The effective atomic number (Zeff)values peak at low photon energies and rise significantly with increasing PbO content. The MFP and TVL of the BTSZP glasses are compared against previously tested glass samples at a set energy, and the values demosntrated the effectiveness of the BTSZP glasses.

Physical and Optical Properties of Lead-Tungsten-Tellurite Glasses

By using the melt quenching approach, a number of tellurite-based heavy metal oxide glasses codoped with varied lead oxide (PbO), (80-x)TeO2-20%WO3-xPbO (x = 5, 10, 15 and 20 mol%) compositions, have been created. By using UV-Vis-IR spectroscopy, forbidden energy gap, Urbach energy, and refractive index were calculated and the contribution of PbO to the glasses structure was investigated. Calculations were also made for physical parameters such as density, molar mass, and oxygen packing density, polaron radius, inter-ionic distance, and molar refraction. The direct and indirect optical band gaps is 3.29 to 3.33 eV and 3.2 to 3.3 eV, respectively. The fact that the nonbridging oxygen ion content rises with increasing PbO content and shifts the band edge to lower frequencies, may be the cause of a drop in the values of the energy band gap Eg.

An exploration of the physical, optical, mechanical, and radiation shielding properties of PbO–MgO–ZnO–B2O3 glasses

Abstract This study presents the results of an investigation into the physical, optical, and mechanical characteristics of glasses prepared from a mixture of ZnO, MgO, B2O3, and PbO. It was found that increasing the concentration of PbO in the glasses led to an increase in both the density (ρ) and molar mass (M). The addition of PbO also affected the packing arrangement of oxygen atoms in the glass network, resulting in changes to the oxygen molar volume (V o) and oxygen packing density. Furthermore, the investigation found that the optical basicity (Ʌ th) of the glass elevated with increasing PbO concentration. Finally, the behavior of the average electronegativity (χav) and electronic polarizability ( α o − 2 {\alpha }_{{\rm{o}}}^{-2} ) with respect to the concentration of PbO in the glasses is discussed, whereby the addition of PbO affected the glasses’ mechanical characteristics as follows: (i) the addition of PbO increased the complexity of the glass network by enhancing the average cross-link density ( n c ̅ \bar{{n}_{{\rm{c}}}} ) and the number of bonds per unit volume of the glasses (n b); (ii) the glasses’ Young’s modulus (E), bulk modulus (B), and shear modulus (G) declined as the mol percent of the PbO increased; (iii) the longitudinal modulus (L) reduced but remained greater than G; (iv) the glass network cross-linking reduced the Poisson ratio (σ); (v) the glasses’ fractal bond connectivity (d) values indicated a three-dimensional network; and (vi) lead oxide hardened the glass, suggesting that a stronger structure manifests. These findings collectively demonstrate that PbO improves the rigidity and interconnectivity of glass. The gamma radiation-shielding characteristics of the glasses were evaluated using the Phy-X software in the 0.015–15 MeV energy range. The radiation-shielding properties of the studied glasses can be compared with other materials by introducing a new parameter known as the radiation coefficient ratio (R). It is observed that Q4 glass sample had superior shielding performance.

Determination of X-ray and gamma-ray shielding capabilities of recycled glass derived from deteriorated silica gel

We determined the radiation shielding properties for 10CaO–xPbO–(90-x) deteriorated silica gel (DSG) glass system (x = 20, 25, 30, 35, 40, and 45 mol.%). The mass attenuation coefficient (MAC) has been estimated at photon energies of 74.23, 97.12, 122, 662, 1173, and 1332 keV using a narrow beam X-ray attenuation and transmission experiment, the XCOM program, and a PHITS simulation. The obtained MAC values were applied to estimate the half value layer (HVL), mean free path (MFP), effective atomic number, and effective electron density. Results show that the MAC value of the studied glasses ranges between 0.0549 and 1.4415 cm2/g, increases with the amount of PbO, and decreases with increasing photon energy. The HVL and MFP values decrease with increasing PbO content and increase with increasing photon energy. The recycled glass, with the addition of PbO content (20–45 mol.%), exhibited excellent radiation shielding capabilities compared to standard barite and ferrite concretes and some glass systems. Moreover, the experimental radiation shielding parameters agree with the XCOM and PHITS values. This study suggests that this new waste-recycled glass is an effective and cost-saving candidate for X-ray and gamma-ray shielding applications.

Physical and optical properties of ternary lead-bismuth tellurite glass

A series of six lead-bismuth tellurite glass samples were prepared by using the melt quenching technique. The Physical properties of the samples such as density and molar were studied. The measurements of density were calculated via using Archimedes' principle. XDR technique was used to confirm the amorphous nature of the samples. The optical properties of the samples such as direct and indirect bandgaps were calculated based on the Davis-Mott equation by employing Tauc's method. The disorderliness of the glass system was measured by calculating Urbach energy and steepness. Density and refractive indices results show an increasing trend with increasing PbO concentration. The non-metallic nature of the samples was investigated by using the metallization criterion. Optical basicity and basicity moderating parameters were calculated for each glass sample by using Duffy and Ingram formula. The metallization criterion results of the synthesized glasses are best for nonlinear optical devices.

Synthesis, optical, structural, physical, and experimental gamma-ray transmission properties of high-density lead-boro-tellurite glasses: A multi-phases investigation towards providing a behavioral symmetry through Lead(II) oxide

We report the synthesis and multiple material properties of newly designed high-density lead-boro-tellurite glass system. The glass formulation as zPbO + [(100-z)(0.2B2O3 + 0.8TeO2)], where z: 10, 15, 20, and 25 mol%, were synthesized using a traditional melting technique around 625 to 725 °C. After successfully preparing the glass samples coded BT20-Pb10, BT20-Pb15, BT20-Pb20, and BT20-Pb25, some physical, structural, and optical analyses were included to serve up a broad understanding. BT20-Pb10, had a density of 5.4125 g/cm3, whilst BT20-Pb25 possessed a density of 6.0756 g/cm3. According to the XRD method, all samples except for BT20-Pb25 had an amorphous structure without any sharp peaks. Furthermore, the transmission percentage was in a decreasing trend parallel to the increasing PbO concentration. This phenomenon also influenced on energy bandgap values to reduce from 2.70 to 2.45 eV for BT20-Pb10 to BT20-Pb25 samples, respectively. In addition to the material characterizations, we studied experimental and theoretical radiation shielding properties. Using experimental methods, the photon absorption properties of the manufactured glasses were studied, and we found out that the BT20-Pb25 sample exhibited the highest MAC values among the compared glasses. Based on MAC findings, other essential parameters, such as HVL and Zeff, were found to be in enhancing way as PbO increased in the glass network. In the context of benchmarking of findings with theoretical and experimental results, it was clearly demonstrated that precise harmony reigns when all eight energy values are taken into account. To sum up, BT20-Pb25 may be regarded as a potential shielding glass for various applications in radiation fields owing to its significant material properties and shielding performance against energetic photons.

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.

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.

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.

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.

Effect of PbO on the elastic and radiation shielding properties of B2O3–Bi2O3–Al2O3–CuO glasses

Investigations of quinary B2O3–Bi2O3–Al2O3–CuO–PbO glasses have been accomplished. The density and the ultrasonic velocities variations were exploited to establish the elastic parameters of the glasses. In addition, a correlation between the ultrasonic parameters and the structural modifications characterized by the FTIR spectra to clarify the function of PbO was achieved. The FTIR spectra suggest that PbO is possibly implanted into the aluminum-borobismuthate network forming [PbO6] units, while Bi2O3 and Al2O3 affect the network with [BiO6] and [AlO6] structural units. Furthermore, the changes of the structure and the elastic moduli were understood based on the vibrations of lead, aluminates, bismuthate, and borate structural units on one side and the substitution of high-bond strength B2O3 via low-bond strength PbO. The results of γ-ray attenuation-coefficients indicate that the values of the mass attenuation coefficient (μm), effective atomic number (Zeff), and electron density (Ne) of the prepared samples increase as a function of PbO content. Additionally, the half-value layer (HVL) and the mean free path (MFP) decrease with increasing PbO content. The glass sample 60.5B2O3–20Bi2O3–7Al2O3–0.5CuO–12PbO (mol%) exhibits the highest values of μm (0.15521 at 356 keV), Zeff (26.67 at 356 keV), and Nel (3.24 at 356 keV) and the lowest elastic moduli (Young’s modulus 80.7 GPa and bulk modulus 48.6 GPa).

Experimental characterizations and molecular dynamics simulations of the structures of lead aluminosilicate glasses

Exploring the atomic-level structure of lead aluminosilicate glass is extremely important for improving the performance of the related products such as optical devices and semiconductor packages. In this work, we developed a set of potential parameters for the lead aluminosilicate ternary system. Raman and X-ray photoelectron spectroscopy were used to obtain structural information of the glass, and the results were compared with those of MD simulations to elucidate the structural details of a series of lead aluminosilicate glasses. It is found that both silicon and aluminum assume four-fold coordination and form the backbone of the network structures. At a low PbO content, Pb2+ plays the role of both charge compensators and network modifiers. When the PbO content exceeds 30mol%, some Pb2+ ions will be incorporated into the network that leads to rearranging of the network structures. After entering the glass network, Pb2+ ions first break the Al-O-Si linkages to form the Si-O-Pb and Al-O-Pb bonds. Then the remaining Pb2+ ions preferentially form the Pb-O-Pb bonds. It is found in the Raman spectra and X-ray photoelectron spectra that the number of lead ions in ionic state is decreasing and that in covalent state is increasing with the increase of PbO content, confirming the results from MD simulations. In addition, the network formers first shift to a high degree of polymerization and then gradually depolymerize, which is consistent with the results in MD simulations.

Lead silicate glass structure: New insights from diffraction and modeling of probable lone pair locations

AbstractStructures of binary PbO‐SiO2 glasses have been studied in detail over the compositional range 35 to 80 mol% PbO using high‐resolution neutron diffraction, high‐energy X‐ray diffraction, static 207Pb NMR, and structural modeling. The changes in the local environment of Pb(II) are subtle; it has a low coordination to oxygen (∼3 to 4) plus a stereochemically active electron lone pair and, thus, behaves as a glass network forming (or intermediate) cation over the entire composition range. This conclusion contradicts previous reports that Pb(II) is a network modifier at low concentrations, and is supported by an analysis of lead and alkaline earth silicate glass molar volumes. The Pb‐O peak bond length shortens by 0.04 Å with increasing PbO content, indicating stronger, more covalent bonding, and consistent with an increase in the number of short (≤ 2.70 Å) Pb‐O bonds, from 3.3 to 3.6. This is accompanied by increased axial symmetry of the Pb(II) sites, and is interpreted as a gradual transition toward square pyramidal [PbO4] sites such as those found in crystalline PbO polymorphs. An attendant decrease in the periodicity associated with the first sharp diffraction peak (FSDP) toward that of β‐PbO, accompanied by increases in the correlation lengths associated with the plumbite network (FSDP) and silicate anions (neutron prepeak), provides evidence of increased intermediate‐range order and has implications for the glass forming limit imposed by crystallization. Pb(II) electron lone pairs occupy the natural voids within the silicate network at low PbO contents, while at high PbO contents they aggregate to create voids that form part of the plumbite network, analogous to the open channels in Pb11Si3O17 and the layered structures of α‐ and β‐PbO. Si‐O and Pb‐O bond lengths have been correlated with 29Si and 207Pb NMR chemical shifts, respectively. This is the first time that such correlations have been demonstrated for glasses and attests to the accuracy with which pulsed neutron total scattering can measure average bond lengths.