PbO SiO2 Glasses Research Articles

The influence of the Cr2O3–Mn2O3 colorants system on the spectral characteristics of R2O–PbO–SiO2 glasses

AbstractThe focus of this paper centers on an exploration of optical glasses with high transmittance within the infrared spectrum at wavelength of 1 060 nm, while concurrently demonstrating full absorption within the ultraviolet and visible spectral ranges. The paper analyzes the present state of glasses demonstrating necessary transmittance at IR range, considering their inherent strengths and limitations. In this context, an R2O–PbO–SiO2 glass system with Cr2O3–Mn2O3 colorants system emerges as the subject of this research. Research was conducted to comprehensively assess the impact of this colorant system on the glass spectral characteristics, while considering the potentially detrimental influence of FeO.The principles underlying the industrial production of these glasses are systematically elucidated and presented. It was discovered that using gas heating during the cooling phase of glass melting resulted in the disruption of the spectral homogeneity of the glass, ultimately leading to defective product outcomes. Implementing the methodology of gasless temperature reduction (inertial cooling process) before glass pouring has created a favorable environment for producing high‐quality items. Glass samples from the laboratory tests were obtained, and the researched glass was integrated into serial production.

Effect of CdS on optical properties of ZnO–PbO–SiO2 glass–ceramic systems

Effect of CdS on optical properties of ZnO–PbO–SiO2 glass–ceramic systems

The structure of CaO–SiO2 and PbO–SiO2 glasses

Whereas the cybotactic theory and thermodynamic modelling have proved invaluable tools in understanding the structures and properties of alkali silicate glasses, questions have been raised as to their validity for alkaline earth and related glasses such as PbO–SiO2. The present paper discusses the specific cases of the CaO–SiO2 and PbO–SiO2 systems, and it is shown that the presence of Si[3] units (silicate tetrahedra with three bridging and one nonbridging oxygen atoms) can easily be explained in terms of the thermodynamic equilibria that underlie the model of associated solutions and the cybotactic theory. Similarly, the much more random distribution of silicate tetrahedral species in PbO–SiO2 glasses derives from the amphoteric nature of PbO. A related question concerns the relevance of atomistic structural modelling/simulation to the evaluation of structural theories of glasses, but to date all of the models of binary silicate glasses have been generated using periodic boundary conditions, which means that they are incapable of reproducing the long range disorder that characterises the vitreous state. Furthermore, it is demonstrated that, in their present form, the RMC and related computer codes, such as EPSR, are fundamentally flawed, in that they merely involve the fitting of an early crystallite model to experimental diffraction data, albeit one where the average internal structure of the crystallites is based on a large highly disordered unit cell, but the crystallites themselves have an entirely unphysical shape. It is also concluded that, to fully interpret the structure of binary and multicomponent glasses, it is essential to study the relevant phase diagram, together with the structures of the thermodynamically-stable and metastable crystalline phases that occur in that particular glass-forming system, and to understand that, since the supercooled liquid is only transiently metastable, the cybotactic/chemical grouping species present in the final glass may not necessarily be determined by equilibrium thermodynamics, but may be greatly influenced by the quench rate. The temperature range over which these crystalline phases/polymorphs are stable is also important, as is the temperature dependence of the glass transition temperature, Tg, and its relationship to the solidus temperature, Ts, at the same composition. Only in this way is it possible to derive the maximum information concerning the structure of a given glass and, much more importantly, to explain why this glass has its particular structure. It is therefore concluded that the key to developing a comprehensive theory of the formation and structure of the vitreous state lies not with ever more precise determinations of the short range order (i.e. diffraction studies), but rather in understanding the role of the thermodynamic equilibria that drive the characteristic long wavelength fluctuations in both number density and composition that distinguish the vitreous from the crystalline state.

Characterization of glass beads from Nanhai I shipwreck and new evidence of lead tin yellow type II in China

Glass beads excavated from Nanhai I shipwreck were investigated with scanning electron microscopy with energy dispersive spectrometer (SEM–EDS), Raman spectroscopy, multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) and X-ray diffraction (XRD). Dating back to the Southern Song Dynasty, these beads help to study Chinese maritime trades during the twelfth–thirteenth century. The bead samples are categorized into five groups by color, i.e., yellow, orange-red, blue, dark red and light red. All beads are of K2O-PbO-SiO2 and PbO-SiO2 glass systems and in form of coil bead, which further confirms the Chinese origin of them. Lead tin yellow type II was identified in the opaque yellow coil beads, and K2SnxPb(1-x)Si3O9 crystals were found in both yellow and orange-red samples. Through the preparation of glass with the same formula as the ancient yellow beads, lead tin yellow type II was probably synthesized beforehand and added as colorant because its raw materials tend to form K2SnxPb(1-x)Si3O9 crystals in the K2O-PbO-SiO2 glass during firing. As lead tin yellow type II is an atypical colorant in China, these beads from Nanhai I shipwreck may serve as the first clear evidence of lead tin yellow type II presenting in the Chinese glass system. The lead isotope ratios of the yellow beads suggest they were produced in Fujian Province, China. The introduction of the lead tin yellow coloring technique might have a close connection to the glass making in the Southeast Asia and these beads seemed to be made specifically for overseas markets.

Opaque ancient K2O\u2013PbO\u2013SiO2 glass of the Southern Song Dynasty with fluorite dendrites and its fabrication

Here we first report a piece of K2O–PbO–SiO2 ancient glass opacified by fluorite dendrites with archaeological background. This piece of glass was excavated from Nanhai I shipwreck, a merchant ship once heading for Southeast Asia, but sinking near Yangjiang, Guangdong province. Analysis of scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction and Raman spectroscopy were used to identify the glass matrix and the fluorite dendritic crystals within it. The elemental feature is consistent with the prevailing K2O–PbO–SiO2 glass system during Tang and Song Dynasties. However, the presence of fluorite dendrites with almost no Na, Al and P elements strongly suggests an astonishing conclusion that the fluorite has already been used as an opacifying agent around 800 years ago. Moreover, through replication of glass samples with similar compositions to the ancient one, it is suggested that fluorite dendrites with a similar size can be obtained when fired at around 1000–1050 °C and cooled within the furnace. On the basis of different crystal growth outcomes of two cooling strategies and the presence of the large undisturbed dendrite, it is inferred that the original glass vessel was probably made though die-casting instead of blowing technique.

Thermal, electrical, and magnetic properties of Fe2O3–PbO–SiO2 glass prepared by traditional melt-quenching and twin roller fast-cooling methods

In this study, Fe–Pb–Si oxide glasses containing between 12.5 and 17.5 mol% Fe2O3 were prepared using two different methods comprising traditional melt-quenching and twin roller fast-cooling techniques. The topography and structure of the materials obtained were characterized by X-ray powder diffraction and scanning electron microscopy. All of the materials were found to be amorphous. The topography of most of the glasses comprised random or evenly distributed nanostructures, where the size and amount were dependent on the iron content and preparation technique. The thermal properties of the glasses were analyzed by differential scanning calorimetry, which showed that the glass transition temperatures varied between 529 °C and 552 °C. The electric conductivity and magnetic susceptibility of the glasses were analyzed by impedance spectroscopy and with an alternating current magnetic properties measurement system, respectively. The measurements of the electrical properties indicated a relatively low activation energy for direct current conductivity (∼0.5–0.68 eV), which is typical of the polaron hopping mechanism. All of the materials exhibited magnetic hysteresis loops and they were ferromagnetic.

Effect of glass composition and finite size on the properties of PbO-SiO2 glasses: A comparative study of bulk and nanoglasses

The present work is an attempt to study the structural and acoustical difference between bulk and nanoglasses. Lead silicate glasses were prepared for (100-x) PbO- x SiO2 (x=40, 50, 60mol%) by melt quenching, sol-gel and hybrid method. Non-destructive ultrasonic Pulse echo method was used to measure the acoustical parameters and the obtained results were briefly analyzed based on the composition and preparation methods of the glasses. Structural and dielectric properties were studied for 50PbO-50SiO2 glasses using XRD, Raman and Impedance spectroscopy. Raman results reveal that incorporation of nanophase has considerable effect on the glass transition temperature. Impedance spectra explain the dominance of grain boundary effect with homogenous distribution. Comparative study of bulk vs. nanoglasses shows enhanced acoustical, structural and dielectric properties to be suitable for electronic and shielding applications.

A comparative study: On the properties of PbO-SiO2 glass systems synthesized via different routes

The present work is an attempt to modify the conventional glass preparation technique to make it suitable for developing high quality nanoglasses for technical applications. Lead oxide doped silicate glass systems (PbO-SiO2) were prepared by employing three different morphological combinations of the precursor materials. The bulk glass (BB) was prepared using both the precursors of PbO and SiO2 in bulk phases. The nanoglass (NB) was synthesized by doping PbO nanoparticles into the bulk phase SiO2 matrix. In the sol-gel glass (NN) both PbO and SiO2 precursors were in the nanophases. Conventional melt quenching technique was also used to obtain the glasses in their final rigid form. XRD, FESEM, FTIR, UV–vis DRS and PL were used to characterize the physical properties of the three glasses. A comparative study of the results indicated the superiority of the NB and NN glasses in certain desired aspects over the BB glass.

Amplification of green emission of Ho3+ ions in lead silicate glasses by sensitizing with Bi3+ ions

This investigation is mainly devoted to the studies on enrichment of green emission of Ho3+ ions in PbOSiO2 glasses containing 1.0 mol% of Ho2O3 by co-doping with different concentrations of Bi2O3 (0–9.0 mol%). The optical absorption spectra, photoluminescence spectra, photoluminescence decay, IR and Raman spectral studies on the above mentioned glasses have been performed as a function of Bi2O3 concentration. The emission spectra of Bi2O3 free glasses exhibited green and red emissions due to 5S2 + 5F4 → 5I8 and 5F5 → 5I8transitions of Ho3+ ions, respectively, when excited at 450 nm. The spectra also exhibited NIR emission due to the5I7 → 5I8transition at 2.0 μm. The intensity of green emission is found to be significantly enhanced (nearly three times) when the glasses are mixed with 5.0 mol% of Bi2O3. The reason for this enhancement has been identified as being due to the energy transfer from Bi3+ to Ho3+ ions. The predominant participation of Bi3+ ions in modifying positions and due to the de-clustering of Ho3+ ions are found to be the other reasons. The overall enhancement of emission has further been explained with the help of rate equations. The quenching of luminescence emission observed in the glasses containing more than 5.0 mol% of Bi2O3 is attributed to the reason that in these glasses the Bi3+ ions largely participate in the network forming positions and increase the phonon losses. These arguments have been quantitatively explained with the help of IR and Raman spectral studies.

The de-clustering influence of aluminum ions on the emission features of Nd3+ ions in PbO–SiO2 glasses

Nd3+ doped lead alumino silicate glasses with varying concentration of Al2O3 (from 5 to 10mol%) have been synthesized. The IR and Raman spectral studies of these glasses have indicated that there is a gradual increase in the depolymerization of the glass network with increase in the concentration of Al2O3. The optical absorption, luminescence spectra and fluorescence decay curves of these glasses were recorded at room temperature. From these studies, the radiative parameters viz., spontaneous emission probability A, the total emission probability, the radiative lifetime τ, the fluorescent branching ratio β of different transitions originated from 4F3/2 level of Nd3+ ions have been evaluated. A clear increase in the quantum efficiency and luminescence emission of the two prominent NIR bands of Nd3+ ions viz., 4F3/2→4I11/2, 13/2, is observed with increase in the concentration of Al2O3. The increase has been attributed to the possible admixing of wavefunctions of opposite parities and due to the declusterization of Nd3+ ions by Al3+ ions in the glass network.

The effect of lead-glass additives on densification and dielectric properties of Ba0.4Sr0.6TiO3 ceramics

Effects of lead-glass additives on the densification, microstructure and dielectric properties of Ba0.4Sr0.6TiO3 (BST) were investigated. Three simple glass systems including PbO-SiO2, PbO-SiO2-B2O3, and PbO-ZnO-B2O3 were employed. 4 wt% lead-containing glass was added to BST ceramics, which accelerated densification with limited grain growth. The sintering temperatures of lead glass added BST ceramics were lowered to 1000 °C∼1050 °C with high density above 96%, which were all higher than that of the pure BST sintered at 1350 °C. The dielectric constant of BST ceramics with PbO-SiO2 glass additives was higher than that of the pure BST ceramics and dissipation factor of all BST samples with lead glass additives was lower than 1×10-3 at 1 kHz

Gamma-ray shielding and structural properties of PbO–SiO2 glasses

Gamma-ray attenuation coefficients have been determined experimentally using a narrow beam transmission method for the xPbO(1−x)SiO2 (x=0.45–0.70) glass system at 662, 1173 and 1332keV photon energies. These values have also been obtained theoretically using the ‘mixture rule’ and the ‘XCOM’ computer software. The results have been used to calculate half value layer parameters. Gamma-ray shielding properties of PbO–SiO2 glass samples have been compared with standard radiation shielding concretes. The molar volume, FTIR and acoustic investigations have been used to study the structural properties of the prepared glass system.

High resolution O 1s XPS spectral, NMR, and thermodynamic evidence bearing on anionic silicate moieties (units) in PbO-SiO2 and Na2O-SiO2 glasses

Recent technical advances in X-ray photoelectron spectroscopy (XPS) have largely overcome differential charging of insulator surfaces, with the result that O 1s linewidths for silicates can be routinely collected that are 50% to 100% narrower than had been previously obtainable. The bridging and nonbridging oxygen signals of glasses are well resolved and now can be accurately measured by XPS without resorting to ad hoc fitting procedures. All O 1s spectra of silicates collected so far are somewhat asymmetric to the high binding energy side of the peak, a characteristic due primarily to vibrational contributions in the ion state produced by photoemission (electronic excited state). This asymmetry must be considered if the proportion of bridging to nonbridging oxygen ratios are to be accurately determined from the XPS O 1s spectra of silicates. X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) experiments yield similar silicon-bridging oxygen (Si-O-Si) concentrations for PbO-SiO2 glasses. The data are proof that the reaction, 2PbO + SiO2 [Formula: see text] Pb2SiO4, does not go to completion (i.e., one or other reactant is not completely consumed). Instead, the data indicate that an equilibrium exists among these constituents, with the equilibrium constant for the reaction being near 15; ergo, some metal bridging oxygen (MBO or Pb-O-Pb), silicon bridging oxygen (BO or Si-O-Si), and nonbridging oxygen (NBO or M-O-Si) are present over the entire range of binary melt compositions. NMR and XPS spectroscopic techniques yield substantially different Si-O-Si concentrations in Na2O-SiO2 glasses of intermediate to high Na2O content. XPS experiments indicate higher proportions of Si-O-Si in Na2O-rich glasses than do the NMR studies. In spite of the different results, three independently collected sets of NMR experiments are similar and yield similar Si-O-Si concentrations. Five XPS experimental studies are likewise self-consistent (but different from the NMR studies). Comparison of data from the two spectroscopic techniques indicates that all experimental spectra are of good or reasonable quality, so that systematic experimental problems or the interpretation (i.e., fitting) of these spectra may be incorrect for one or both types of spectral data. Viscosity, conductivity, and the XPS data are consistent with (but not proof for) formation of an Na2Si2O5 species in the Na2O-SiO2 glasses. The most comprehensive NMR study is, by contrast, consistent with the formation of an orthosilicate species (Na4SiO4). The NMR and XPS results cannot yet be reconciled and additional experimental studies are required to resolve and to understand better Na2O-SiO2 liquids and glasses.Key words: XPS, high resolution, silicate glass, NMR.

PIXE and ICP-AES analysis of early glass unearthed from Xinjiang (China)

Early glasses (about 1066 BC–220 AD) unearthed from Xinjiang of China were chemically characterized by using PIXE and ICP-AES. It was found that these glasses were basically attributed to PbO–BaO–SiO2 system, K2O–SiO2 system, Na2O–CaO–SiO2 system and Na2O–CaO–PbO–SiO2 system. The results from the cluster analysis showed that some glasses had basically similar recipe and technology. The PbO–BaO–SiO2 glass and the K2O–SiO2 glass were thought to come from the central area and the south of ancient China, respectively. The part of the Na2O–CaO–SiO2 glass (including the Na2O–CaO–PbO–SiO2 glass) might be imported from Mesopotamia, while the other part might be locally produced.

Structural Study on PbO–SiO2 Glasses by X‐Ray and Neutron Diffraction and 29Si MAS NMR Measurements

Structure of xPbO–(100−x)SiO2 (x=25–89) glasses has been investigated by means of the X‐ray and neutron diffraction and 29Si MAS NMR measurements. In the radial distribution functions of all the glasses, the Pb–O correlation was observed at 0.23 nm, indicating that the PbO3 trigonal pyramids units do exist in the whole glass forming composition range. Furthermore the existence of the first Pb–Pb correlation at ∼0.385 nm in the whole composition range suggests that the basic structural unit is considered to be a Pb2O4 unit, which consists of the edge‐shared PbO3 trigonal pyramids. These results strongly imply that the Pb2O4 units participate in the glass network constructed by SiO4 tetrahedra even at low PbO content. Differing from other lead‐containing glass systems, these structural characteristics of Pb ions in the PbO–SiO2 glass system are responsible for the extremely wide glass‐forming region.

Optical nonlinearity in PbO–SiO2 glass: Kramers–Kronig analyses

Relationship between nonlinear refractivity and two-photon absorption has been studied for PbO–SiO2 glasses using a nonlinear Kramers–Kronig relation. Nonlinear refractive indices, which are determined with z-scan measurements, are consistent with those which are calculated using the relation from two-photon absorption spectra. This consistency suggests that large intensity-dependent refractivity in this glass system arises from resonant two-photon electronic transitions from oxygen 2p to lead 6p states.

Two-photon optical absorption in PbO-SiO2 glasses

One- and two-photon absorption spectra in PbO-SiO2 glasses have been studied comparatively as a function of the PbO content. The two spectra show different composition dependence, which can be accounted for by taking related electronic wave functions and the densities-of-states into account. This interpretation can be extended to understand high optical nonlinearity in heavy-metal oxide glasses.

Second-Harmonic Generation from Thermally Poled PbO-GeO2 Glasses.

Second-harmonic generation (SHG) was observed from PbO-GeO2 glasses after thermal poling. As in PbO-SiO2 glasses, the compositional dependence of SHG intensity was found, although the SHG intensity was rather small. The largest SHG intensity was observed for about PbO=35mol%. On the basis of extended X-ray analysis fine structure (EXAFS) results previously obtained, it was considered that remarkable increase of SHG intensity found for PbO>20mol% was caused by the formation of non-bridging oxygens. On the other hand, then the decrease of the intensity at PbO>35mol% was due to the disappearance of non-bridging oxygens.

The Urbach rule for the PbO-SiO2 glasses

An analysis is made of the behavior of optical spectra of lead-silicate glasses, with variable lead content near the UV absorption edge, and within the 80–470-K range. A generalized formulation of the modified Urbach rule, applicable to glassy materials within a broad temperature range, is proposed for the interpretation of experimental spectral relations. Within this approach, the effective energies of the phonons responsible for the temperature-induced shift of the Urbach edge have been calculated. It is shown that the spectral and temperature parameters of the modified Urbach rule are structure-sensitive, and that their concentration behavior reflects the change of the type of short-range order in the glassy matrix.

Polishing Rate of BaO-B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub>, PbO-SiO<sub>2</sub> and PbO-B<sub>2</sub>O<sub>3</sub> Glasses

BaO-B2O3-SiO2, PbO-SiO2 and PbO-B2O3 glasses were polished using a pitch polisher and cerium oxide dispersed in distilled water. The factors affecting the polishing rate at initial stage were discussed in terms of glass properties: Vickers microhardness, chemical water durability and bulk modulus. The polishing rate of BaO-B2O3-SiO2 glasses depends mainly on the hardness of the hydrated layer formed; this factor is consistent with Izumitani proposal. The polishing rates of PbO-SiO2 and PbO-B2O3 glasses increase with increasing PbO content up to 50mol% PbO and then decrease remarkably. The polishing rates of PbO-SiO2 and PbO-B2O3 glasses are apparently affected by the bulk modules which is related to the product of the ratio of plastic strain to elastic strain (c/a) and the indentation hardness H using Hill's theory on plastic-elastic materials.