- 1 Saxon Drive
Alfred
14802, NY, USA
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Lead‐containing alkali/alkaline‐earth borate and barium lead phosphate glasses were prepared by melt‐quenching for a detailed investigation of the Pb2+ ions’ optical properties. UV–Vis absorption and photoluminescence spectroscopy reveal... more
Lead‐containing alkali/alkaline‐earth borate and barium lead phosphate glasses were prepared by melt‐quenching for a detailed investigation of the Pb2+ ions’ optical properties. UV–Vis absorption and photoluminescence spectroscopy reveal variations in the s–p transition of Pb2+, which are shown to correlate with the optical basicity of the host glass in both borates and phosphates. Pb2+ emission differs significantly for borate and phosphate glasses, as the nature of the charged sites available to accommodate Pb2+ cations vary. Optical basicity values were determined from the composition (Λth) and the measured refractive index (Λn). The UV‐cutoff shifts toward higher wavelengths with increasing optical basicity and lead content. In borate glasses, the frequency of the stretching modes due to nonbridging oxygen atoms of trigonal metaborate species is identified to be inversely proportional to the excitation wavelength (directly proportional to the excitation energy) of Pb2+. Lead‐containing alkali and alkaline‐earth borate glasses show additional correlations between the Pb2+ emission wavelength and the weighted average of the field strength of the modifier(s). Complementary to the investigation of optical properties, radiation and neutron shielding parameters were calculated, suggesting the potential utility of some of the studied compositions for radiation shielding applications.
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We report on the mechanical properties of xCuO-(50-x)PbO-50B2O3 (x from 0 to 30 mol%) copper-lead-borate glasses. Their mechanical properties were investigated by the mechanical resonance technique and by the indentation measurement. The... more
We report on the mechanical properties of xCuO-(50-x)PbO-50B2O3 (x from 0 to 30 mol%) copper-lead-borate glasses. Their mechanical properties were investigated by the mechanical resonance technique and by the indentation measurement. The replacement of lead by copper improves the packing efficiency, and enhances the elastic moduli, hardness and the fracture toughness of glasses.
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Lead‐containing alkali/alkaline‐earth borate and barium lead phosphate glasses were prepared by melt‐quenching for a detailed investigation of the Pb2+ ions’ optical properties. UV–Vis absorption and photoluminescence spectroscopy reveal... more
Lead‐containing alkali/alkaline‐earth borate and barium lead phosphate glasses were prepared by melt‐quenching for a detailed investigation of the Pb2+ ions’ optical properties. UV–Vis absorption and photoluminescence spectroscopy reveal variations in the s–p transition of Pb2+, which are shown to correlate with the optical basicity of the host glass in both borates and phosphates. Pb2+ emission differs significantly for borate and phosphate glasses, as the nature of the charged sites available to accommodate Pb2+ cations vary. Optical basicity values were determined from the composition (Λth) and the measured refractive index (Λn). The UV‐cutoff shifts toward higher wavelengths with increasing optical basicity and lead content. In borate glasses, the frequency of the stretching modes due to nonbridging oxygen atoms of trigonal metaborate species is identified to be inversely proportional to the excitation wavelength (directly proportional to the excitation energy) of Pb2+. Lead‐containing alkali and alkaline‐earth borate glasses show additional correlations between the Pb2+ emission wavelength and the weighted average of the field strength of the modifier(s). Complementary to the investigation of optical properties, radiation and neutron shielding parameters were calculated, suggesting the potential utility of some of the studied compositions for radiation shielding applications.
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Despite glasses having an amorphous structure, their atoms are arranged in a certain short-range order and in superstructural units such as chains or rings. Variations in this atomic arrangement depend on the glass composition and... more
Despite glasses having an amorphous structure, their atoms are arranged in a certain short-range order and in superstructural units such as chains or rings. Variations in this atomic arrangement depend on the glass composition and directly influence glass properties, including thermal behaviour or dissolution rates. This chapter describes the structure and properties of three important groups of melt-derived glasses used as biomaterials: silicate, phosphate and borate glasses, as well as some commonly used mixed glass former systems, including phosphosilicate and borosilicate glasses. In addition, the structural features of sol–gel derived silicate glasses are considered.
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Despite glasses having an amorphous structure, their atoms are arranged in a certain short-range order and in superstructural units such as chains or rings. Variations in this atomic arrangement depend on the glass composition and... more
Despite glasses having an amorphous structure, their atoms are arranged in a certain short-range order and in superstructural units such as chains or rings. Variations in this atomic arrangement depend on the glass composition and directly influence glass properties, including thermal behaviour or dissolution rates. This chapter describes the structure and properties of three important groups of melt-derived glasses used as biomaterials: silicate, phosphate and borate glasses, as well as some commonly used mixed glass former systems, including phosphosilicate and borosilicate glasses. In addition, the structural features of sol–gel derived silicate glasses are considered.
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Abstract Fluoride–phosphate (FP) glasses have been developed (in terms of glass forming ability) as a more stable alternative to fluoride glasses. Benefitting from the low polarizability of the fluoride anion, high electronic band-gap and... more
Abstract Fluoride–phosphate (FP) glasses have been developed (in terms of glass forming ability) as a more stable alternative to fluoride glasses. Benefitting from the low polarizability of the fluoride anion, high electronic band-gap and low phonon energy, they present one of the most important host species for the inclusion of rare-earth and other optically active dopants into fiber and bulk glass. A major limitation, however, has been the mechanical performance of these glasses and their susceptibility to damage and fracture. Here, we provide comprehensive data on elasticity, plasticity and fracture of a series of mixed fluoride–phosphate glasses with strongly ionic bonding character, spanning the compositional join of strontium metaphosphate and alkaline earth aluminum fluoride. Simplistic models such as that of Makishima and Mackenzie can reproduce the mechanical properties of these glasses within a limited compositional range. This break-down is explained in the context of glass structure, in particular, the role of intermediate VIAl3 + species which act as bridges between the fluoride and the phosphate sub-networks. A simple binominal model is implemented to estimate the atomic fractions of aluminum as well as of magnesium cations, which are linked to two or more phosphate units, and used as an indicator for the connectivity between the anion sub-networks. Such adjustment of the Makishima–Mackenzie model provides an unambiguous rational for the elastic properties, but also for the susceptibility to inelastic deformation and fracture of FP glasses.
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Glass is a fascinating material, not only because of its transparency and for its formability, but also because of the manifold facets of bright colors it can display. Just remember how the colored glasses of cathedral windows made us... more
Glass is a fascinating material, not only because of its transparency and for its formability, but also because of the manifold facets of bright colors it can display. Just remember how the colored glasses of cathedral windows made us dream in our childhood, and how much we could quarrel in the schoolyard over a marble or a bead necklace.
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OVERVIEWIn theory, any molten material can form a glass when quenched fast enough. Most natural glasses are based on silicates and for thousands of years only alkali/alkaline earth silicate and lead-silicate glasses were prepared by... more
OVERVIEWIn theory, any molten material can form a glass when quenched fast enough. Most natural glasses are based on silicates and for thousands of years only alkali/alkaline earth silicate and lead-silicate glasses were prepared by humankind. After exploratory glass experiments by Lomonosov (18th ct) and Harcourt (19th ct), who introduced 20 more elements into glasses, it was Otto Schott who, in the years 1879–1881, melted his way through the periodic table of the elements so that Ernst Abbe could study all types of borate and phosphate glasses for their optical properties. This research also led to the development of the laboratory ware, low alkali borosilicate glasses. Today, not only can the glass former silicate be replaced, partially or fully, by other glass formers such as oxides of boron, phosphorous, tellurium or antimony, but also the oxygen anions can be substituted by fluorine or nitrogen. Chalcogens, the heavier ions in the group of oxygen in the periodic table (S, Se, Te), on their own or when paired with arsenic or germanium, can function as glass formers. Sulfate, nitrate, tungstate and acetate glasses lack the conventional anion and cation classification, as do metallic or organic glasses. The latter can occur naturally—amber predates anthropogenic glass manufacture by more than 200 million years.In this chapter, we are going to provide an overview of the different glass families, how the structure and properties of these different glass types differ from silicate glasses but also what similarities are dictated by the glassy state. Applications and technological aspects are discussed briefly for each glass family.
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Abstract Alkali germanotellurite glasses of composition 0.3M2O–0.7[(1-x)GeO2–xTeO2], M=Li, Na and 0 ≤ x ≤ 1, were investigated by Raman and infrared vibrational spectroscopic techniques to search for the origins of the alkali... more
Abstract Alkali germanotellurite glasses of composition 0.3M2O–0.7[(1-x)GeO2–xTeO2], M=Li, Na and 0 ≤ x ≤ 1, were investigated by Raman and infrared vibrational spectroscopic techniques to search for the origins of the alkali ion-dependent network former mixing (NFM) effect in these ion-conducting glasses. The vibrational spectra measured on mixed network-former glasses, and the spectral comparison between equimolar-mixed glasses (x = 0.5) and pellet-mixtures of the endmember glasses, 0.3M2O–0.7GeO2 and 0.3M2O–0.7TeO2, provided evidence for the formation of hetero-atomic Ge–O–Te linkages and structural rearrangements in the germanate and tellurite components of the glass. The mixing-induced structural rearrangements were expressed in terms of chemical equilibria between the network-building units and were used to make qualitative predictions for changes in the network cross-linking density and the related network-strain energy, as well as in the binding energy part of the activation energy for ion conduction. Thus, it is proposed that the mixing-induced structural modifications in the germanate and tellurite parts of glass cause the cancelation of changes in the binding energy and the network-strain energy contributions to the activation energy for ion transport. These qualitative predictions were discussed in the context of the previously found absence of an NFM effect in ionic conductivity for M=Na and the presence of a weak positive NFM effect for M=Li.
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For oxynitrides, oxygen and nitrogen polarizabilities were separated. The optical basicity of the isoelectronic anions F−:O2−:N3− varies as follows: Λ(MFm) = 1/2Λ(M2Om) = 1/3Λ(M3Nm).
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Electrothermal poling is shown here to effectively induce second‐order nonlinear effects in heavy‐metal oxide antimonite glasses. In M2O–PbO–WO3–Sb2O3 (M = Li, Na, K) glasses, the poling‐induced second‐harmonic generation intensity is... more
Electrothermal poling is shown here to effectively induce second‐order nonlinear effects in heavy‐metal oxide antimonite glasses. In M2O–PbO–WO3–Sb2O3 (M = Li, Na, K) glasses, the poling‐induced second‐harmonic generation intensity is five times larger than in silica (Infrasil) for M = Na, twice as large as in silica for M = Li, and smaller than in silica for M = K. X‐ray photoelectron spectroscopy suggests that antimony ions exist predominantly in the trivalent oxidation state in the studied glass samples. Raman and infrared spectroscopy confirm that the glass network is comprised of SbO3, WO4, WO6, and PbO4 units—with some SiO4 moieties due to leaching from the silica crucible. The WO4 units appear to exist in two distinct sites, as evidenced by comparison of the vibrational spectra of alkali–tungsten–antimonite glasses with those of previously reported crystalline tungstate phases. The alkali type influences the equilibrium between tetrahedral tungstate anions, [WO4]2−, and the i...
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Ultralow expansion (ULE) glass, a binary TiO2–SiO2 glass with 5.67 mol % TiO2, was exposed to microindentation. Vitreous silica was similarly treated and used as a reference material, including the...
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Electrical properties of beryllium-alumino-tellurite glasses and glass–ceramics doped with iron ions were studied using impedance spectroscopy. The conductivity was measured over a wide frequency range from 10 mHz to 1 MHz and the... more
Electrical properties of beryllium-alumino-tellurite glasses and glass–ceramics doped with iron ions were studied using impedance spectroscopy. The conductivity was measured over a wide frequency range from 10 mHz to 1 MHz and the temperature range from 213 to 473 K. The D.C. conductivity values showed a correlation with the Fe-ion concentration and ratio of iron ions on different valence states in the samples. On the basis of Jonscher universal dielectric response the temperature dependence of conductivity parameters were determined and compared to theoretical models collected by Elliott. In glasses, the conduction process was found to be due to the overlap polaron tunneling while in glass–ceramics the quantum mechanical tunneling between semiconducting crystallites of iron oxides is proposed. The D.C. conductivity was found not to follow Arrhenius relation. The Schnakenberg model was used to analyze the conductivity behavior and the polaron hopping energy and disorder energy were ...
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Using niobium crucibles for melting phosphate and silicate glasses of various modifier oxide contents, and therefore varying optical basicity (Λ), was found to result in varying dissolution rates of niobate during melting. Because of... more
Using niobium crucibles for melting phosphate and silicate glasses of various modifier oxide contents, and therefore varying optical basicity (Λ), was found to result in varying dissolution rates of niobate during melting. Because of their high electronic polarizability, even small concentrations of niobates are detectable in the Raman spectra of glasses. Even <1 mol% Nb2O5 can be identified, as independently confirmed by SEM‐EDX analysis. Silica‐rich glasses (~60% SiO2, Λ ~0.6) did not show significant Nb dissolution from the crucible, while higher basicity metasilicate glasses (~50% SiO2, Λ ~0.65) and pyrophosphate glasses (~30% P2O5, Λ ~0.7) did show the typical niobate signature in the Raman spectra at 810–840 cm−1, depending on composition. While niobium is well‐dissolved throughout the pyrophosphate glass, metasilicate glasses showed a much more intense Raman signature of niobate units near the outer surface of the glass. Measurements along the cross‐section of a fractured ...
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Abstract In this work, glass-ceramics in the xBeO–20Fe2O3–(80-x)TeO2 system with x = 0–25 mol% were synthesized by the traditional melt quenching route and studied by inductively coupled plasma optical emission spectroscopy, X-ray... more
Abstract In this work, glass-ceramics in the xBeO–20Fe2O3–(80-x)TeO2 system with x = 0–25 mol% were synthesized by the traditional melt quenching route and studied by inductively coupled plasma optical emission spectroscopy, X-ray diffraction, confocal microscopy, infrared and Raman spectroscopy. BeO addition was found to support the crystallization process of Fe2O3 during melting, and an increased BeO content was associated with an increased fraction of the crystalline Fe2O3 phase and an increased size of these crystallites. Furthermore, samples doped with BeO exhibit an increasing polymerization of the residual tellurite glass network compared to the undoped sample. The magnetic properties and specific heat of all synthesized materials were measured, and the results show that all studied samples behave as spin-glasses. Also, the Morin transition of hematite was observed at 260 K with intensity depending on the material content in Fe2O3 crystalline phase, the formation of which correlates with the amount of added BeO.
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Abstract In glasses, even low levels of dopants or impurities can give rise to very intense and broad charge transfer transitions from ligands (e.g. oxygen or fluorine ions) to the metal ion (L→M), absorbing strongly in the short... more
Abstract In glasses, even low levels of dopants or impurities can give rise to very intense and broad charge transfer transitions from ligands (e.g. oxygen or fluorine ions) to the metal ion (L→M), absorbing strongly in the short wavelength ultraviolet. In an attempt of a systematic review of charge transfer transitions, we compile data of various glass systems with high intrinsic transmission that allow the observation of charge transfer (CT) transitions involving cations of different electronic configurations. Various glasses of different composition were selected as matrices, including fluoroaluminate glasses with low P2O5 content (FP10 = 35AlF3–10MgF2–30CaF2–15SrF2–10Sr(PO3)2), phosphate [SrP = Sr(PO3)2, NSP = Na2O-40SrO-50P2O5], silicate (NS = 15Na2O–85SiO2, DS = 33Na2O–67SiO2), aluminosilicate (BCAS = 10BaO–10CaO–15Al2O3–65SiO2) and borosilicate (NBS1 = 16Na2O–10B2O3–74SiO2, NBS2 = 4Na2O–1Al2O3–21B2O3–74SiO2, Duran = 5Na2O/K2O–1Al2O3–12B2O3–82SiO2) compositions. All glasses were prepared from very high purity materials and doped with various metal ions. Charge transfer transitions of electrons to or from these cations induce absorption and photoluminescence phenomena in the ultraviolet and visible spectral region, which were recorded by optical spectroscopy. Charge transfer transitions were considered for empty valence orbitals, that is, for the high valent 3d, 4d and 5d ions, and for Zn2+, Ag+, Cu+ with full d10 orbitals. 3d, 4d and 5d ions with partially filled valence orbitals that could be stabilized in the named glasses are studied as well. Doping concentrations for these allowed transitions typically ranged from 5 to 5000 wt-ppm of metal ions, with some samples also displaying higher dopant levels. Inter valence charge transfer (IVCT) transitions directly from one metal ion to a neighboring metal ion (M→M) of the same element or metal to metal charge transfer (MM-CT) between ions of different elements can also induce strong visible absorption and deep coloring for which some examples will be discussed.