Critical assessment of the elemental composition of Corning archeological reference glasses by LA-ICP-MS

Corning archeological reference glasses A, B, C, and D have been made to simulate different historic technologies of glass production and are used as standards in historic glass investigations. In this work, nanoseconds (193, 266 nm) and femtosecond (800 nm) laser ablation were used to study the elemental composition of Corning glasses using laser ablation inductively coupled plasma mass spectrometry. The determined concentrations of 26 oxides (Li₂O, B₂O₃, Na₂O, MgO, Al₂O₃, SiO₂, P₂O₅, K₂O, CaO, TiO₂, V₂O₅, Cr₂O₃, MnO, Fe₂O₃, CoO, NiO, CuO, ZnO, Rb₂O, SrO, ZrO₂, SnO₂, Sb₂O₅, BaO, PbO, Bi₂O₃) are compared with values reported in the literature. Results show variable discrepancies between the data, with the largest differences found for Cr₂O₃ in Corning A; Li₂O, B₂O₃, and Cr₂O₃ in Corning B; and MnO, Sb₂O₅, Cr₂O₃, and Bi₂O₃ in Corning C. The best agreement between the measured and literature values was found for Corning D. However, even for this reference, glass re-evaluation of the data was necessary and new values for PbO, BaO, and Bi₂O₃ are proposed.     

Impedance spectroscopy of V2O5–Bi2O3–BaTiO3 glass–ceramics

The glasses within composition as: (80 − x)V₂O₅/20Bi₂O₃/xBaTiO₃ with x = 2.5, 5, 7.5 and 10 mol% have been prepared. The glass transition (T_g) increases with increasing BaTiO₃ content. Synthesized glasses ceramic containing BaTi₄O₉, Ba₃TiV₄O₁₅ nanoparticles of the order of 25–35 nm and 30–46 nm, respectively were estimated using XRD. The dielectric properties over wide ranges of frequencies and temperatures were investigated as a function of BaTiO₃ content by impedance spectroscopy measurements. The hopping frequency, ω_h, dielectric constant, ε′, activation energies for the DC conduction, E_σ, the relaxation process, E_c, and stretched exponential parameter β of the glasses samples have been estimated. The, ω_h, β, decrease from 51.63 to 0.31 × 10⁶ (s⁻¹), 0.84 to 0.79 with increasing BaTiO₃ respectively. Otherwise, the E_σ, increase from 0.279 to 0.306 eV with increasing BaTiO₃. The value of dielectric constant equal 9.5·10³ for the 2.5BaTiO₃/77.5V₂O₅/20Bi₂O₃ glasses-ceramic at 330 K for 1 KHz which is ten times larger than that of same glasses composition. Finally the relaxation properties of the investigated glasses are presented in the electric modulus formalism, where the relaxation time and the respective activation energy were determined.     

Structural correlations in BaO–PbO–B2O3 glasses as inferred from FTIR spectra

Infrared spectra of xBaO·(30-x)PbO·70B₂O₃, xBaO·(40-x)PbO·60B₂O₃ and xBaO·(50-x)PbO·50B₂O₃ glasses have been quantitatively analyzed. The fraction of four coordinated boron atoms varies linearly, for each group, between the values of the corresponding binary borate glasses. The data could be used to calculate and follow the composition dependence of the concentration of structural units in all glasses. The results show a linear increase in the ratio of PbO forming BO₄ units to the total content of PbO, with increasing B₂O₃ in binary PbO–B₂O₃ glasses. Similar behavior has been observed for the ratio of BaO forming BO₄ units to the total content of BaO in binary BaO–B₂O₃ glasses. The ratio of PbO forming PbO₄ units to the total PbO content, and that of BaO forming asymmetric BO₃ units to the total BaO content, shows a reversed dependence. The linear change in fraction of four coordinated boron atoms and in density and molar volume suggests that the studied glasses can be treated as mixtures of binary PbO–B₂O₃ and BaO–B₂O₃ matrices.     

Densification mechanisms of alumina,aluminosilicates and aluminoborosilicates gels,glasses and ceramics

The thermal evolution of gels, glasses and ceramics of various more or less refractory compositions (Al₂O₃, 3Al₂O₃2SiO₂, 7Al₂O₃3SiO₂, Al₂O₃2SiO₂, Al₂O₃2SiO₂0.7B₂O₃, Al₂O₃2SiO₂2B₂O₃, Al₂O₃2SiO₂6B₂ O₃) have been studied by dilatometry, DTA, and helium density measurements. Comparison is made for materials prepared by rapid (powder) or by very slow gelation (optically clear monoliths). The influence of atmosphere sintering (air, H₂, vacuum) is reported. Densification and kinetic laws are discussed.Also at LASIR, CNRS, 2 rue Henry Dunant, 94320 Thiais, France.     

Thermal stability and crystallization kinetics of Pb and Bi borate-based glasses

Glasses with compositions 60B₂O₃–40PbO, 60B₂O₃–40Bi₂O₃, and 60B₂O₃–30Bi₂O₃–10PbO have been prepared and studied by differential thermal analysis. The crystallization kinetics of the glasses was investigated under non-isothermal conditions. From dependence of the glass transition temperature (T _g) on the heating rate, the activation energy for the glass transition was derived. Similarly the activation energy of the crystallization process was determined. Thermal stability of these glasses were achieved in terms of the characteristic temperatures, such as the glass transition temperature, T _g, the onset temperature of crystallization, T _in , the temperature corresponding to the maximum crystallization rate, T _p, beside the kinetic parameters, K(T _g) and K(T _p). The results revealed that the 60B₂O₃–40PbO is more stable than the others. The crystallization mechanism is characterized for glasses. The phases at which the glass crystallizes after the thermal process have been identified by X-ray diffraction.     

Application of the “Tg-Δ rule” to the local structural study of ferrate glasses

A linear relationship exists between the glass transition temperature (T _g) and the quadrupole splitting (Δ) of Fe(III). The linear relationship, termed ‘T _g-Δ rule’, has been verified in 60CaO·(40-x)Al₂O₃·xFe₂O₃, 60CaO·10BaO·(30-x) Al₂O₃·xFe₂O₃, 60CaO·(40-x)Ga₂O₃·xFe₂O₃, and 50CaO·(50-x)Ga₂O₃·xFe₂O₃ glasses. In these glasses, both theT _g and Δ decrease linearly with an increasing content of Fe₂O₃ (≈40 mol%). The slope of the straight line, obtained from the plot of theT _g vs. Δ, was calculated to be 670≈700, °C/(mm·s⁻¹), revealing that the Fe(III) constitutes the skeleton of aluminoferrate and galloferrate glasses.     

Approach to thermal properties and electronic polarizability from average single bond strength in ZnOBi2O3B2O3 glasses

The glass transition temperature (T_g), density, refractive index, Raman scattering spectra, and X-ray photoelectron spectra (XPS) for xZnO-yBi₂O₃-zB₂O₃ glasses (x=10-65, y=10-50, z=25-60 mol%) are measured to clarify the bonding and structure features of the glasses with large amounts of ZnO. The average electronic polarizability of oxide ions (α_O2−) and optical basicity (Λ) of the glasses estimated using Lorentz-Lorenz equation increase with increasing ZnO or Bi₂O₃ content, giving the values of α_O2−=1.963 Å³ and Λ=0.819 for 60ZnO-10Bi₂O₃-30B₂O₃ glass. The formation of BOBi and BOZn bridging bonds in the glass structure is suggested from Raman and XPS spectra. The average single bond strength (B_MO) proposed by Dimitrov and Komatsu is applied to the glasses and is calculated using single bond strengths of 150.6 kJ/mol for ZnO bonds in ZnO₄ groups, 102.5 kJ/mol for BiO bonds in BiO₆ groups, 498 kJ/mol for BO bonds in BO₃ groups, and 373 kJ/mol for BO bonds in BO₄ groups. Good correlations are observed between T_g and B_MO, Λ and B_MO, and T_g and Λ, proposing that the average single bond strength is a good parameter for understanding thermal and optical properties of ZnOBi₂O₃B₂O₃ glasses.     

Raman spectroscopic studies on the structure of materials, specially of glasses, ceramics, films and fibres

A survey is given of applications of Raman spectroscopy in materials characterization. The following topics are covered: Analytical characterization of glasses in the system PbO-B₂O₃ and of glasses and ceramics in the system SrO-B₂O₃-Al₂O₃-TiO₂; investigation and discussion of the so-called Boson peak in the Raman spectra of glasses; Raman spectra obtained with a microscope attachment of carbonaceous materials to study the orientation of graphite planes in films and fibres.     

Thermal properties and stability of lithium titanophosphate glasses

DTA was used to study thermal properties and thermal stability of (50-x)Li₂O-xTiO₂-50P₂O₅ (x=0–10 mol%) and 45Li₂Ot-yTiO₂-(55-y)P₂O₅ (y=5–20 mol%) glasses. The addition of TiO₂ to lithium phosphate glasses results in a non-linear increase of glass transition temperature. All prepared glasses crystallize under heating within the temperature range of 400–540°C. The lowest tendency towards crystallization have the glasses with x=7.5 and y=10 mol% TiO₂. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were LiPO₃, Li₄ P₂O₇, TiP₂O₇ and NASICON-type LiTi₂(PO₄)₃. DTA results also indicated that the maximum of nucleation rate for 45Li₂O-5TiO₂-50P₂O₅ glass is close to the glass transition temperature.     

Low-temperature heat capacity of sodium borosilicate glasses at temperatures from 13 K to 300 K

Thermodynamic properties of sodium borosilicate glasses {56.7 SiO₂, (43.7  − x)B₂O₃,xNa₂O} wherex =  14.4, 22.9, and 32.5, have been studied. The heat capacity was measured using an adiabatic calorimeter at temperatures between 13 K and 300 K. The thermodynamic functions were calculated from the smoothed values ofC_{p, m} . The results differ from an additive model with pure glassy SiO₂, B₂O₃, and crystalline Na₂O as components. A model based on the assumption that the contribution of structural units of glasses to the heat capacity is equal to those of glasses with the same molecular formula is proposed.     

The Role of Trivalent Element Oxides in Cao (Na2O)–M2O3–SiO2 Glasses From Tg

In this paper T _g values of calcium (sodium) silicate glasses containing added with oxides of trivalent elements are reported. The plots of T _g as a function of composition or vs. the ionic field strength prove to be useful in discussing the role of the oxides in the glass structure. It is found that, at least in the studied composition range, Sc₂O₃, Y₂O₃, La₂O₃, and In₂O₃, behave as network modifier oxides. In the compositional ranges studied, the hypothesis based on them well agree with the expectations based on the known criteria reported in literature and on FTIR spectra. This revised version was published online in July 2006 with corrections to the Cover Date.     

Glass formation in the CaO-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-B<Subscript>2</Subscript>O<Subscript>3</Subscript> and SrO-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-B<Subscript>2</Subscript>O<Subscript>3</Subscript> systems

A physicochemical study of glasses based on the MO-Bi₂O₃-B₂O₃ and SrO-Bi₂O₃-B₂O₃ systems was performed. Glass formation regions were found. The structural and optical properties, as well as the thermal behavior of the glasses, were studied.     

Thermal Study of A2O–(MoO3)2–P2O5 (A=Li, Na) Glasses

Alkali phosphomolybdate glasses have been prepared by quenching melted mixtures of P₂O₅, MoO₃ and A₂O(A=Li, Na). The composition dependence of the transition temperature of glasses belonging to ternary A₂O–(MoO₃)₂–P₂O₅ (A=Li, Na) systems is studied for several series of glasses corresponding to either a fixed A₂O rate or a constant Mo/P ratio. The interpretation of the results is based on the presence of different types of molybdenum and phosphorous structural groups and P–O–M (M=P, Mo) linkages in glasses. This revised version was published online in August 2006 with corrections to the Cover Date.     

Preparation,structure and properties of silicate-phosphate glasses obtained by means of sol-gel method

Gels, densified amorphous materials and thin layers in SiO₂-P₂O₅, SiO₂-P₂O₅-Al₂O₃ and SiO₂-P₂O₅-Na₂O systems were obtained from alcohol solutions. Detailed DTA, XRD and FTIR investigations were carried out for dried gels and heat-treated samples. It has been found, among others, that the addition of aluminium to the silicate-phosphate glasses eliminates the doubly bonded oxygen (P=O) and leads to the formation of a continuous framework connected with [SiO₄], [PO₄] and [AlO₄] tetrahedra.There were measured the chemical and electrical properties of glasses covered with silicatephosphate gel layers. It has been found that the chemical resistance of the covered glasses is higher than that of the basic, sodium-calcium-silicate glass. Moreover, the silicate-phosphate layers modify the surface electrical conduction of the basic glasses. The layers of systems SiO₂-P₂O₅ and SiO₂-P₂O₅-Al₂O₃ show the electrical conduction considerable higher than the basic glass. The layers containing sodium, depending on its concentration, behave similarly to the basic glass or show lower electrical conductivity.     

Application of heating microscopy to the study of thermal behaviour of ZnO–P2O5–WO3 glasses

The effect of WO₃ on thermal behaviour and thermal stability of ZnO–P₂O₅–WO₃ glasses prepared in compositional series (100 ? x)[0.5ZnO–0.5P₂O₅] ? xWO₃ (x = 0–60) was investigated by heating microscopy and the results were correlated with the results determined by conventional thermodilatometry and differential thermal analysis. Thermoanalytical studies showed that the glass transformation temperature and dilatation softening temperature increase with increasing WO₃ content while thermal expansion coefficient decreases. The highest stability towards crystallization possess glasses containing 20–30 mol% WO₃. Major compounds formed by the crystallization of the glasses were Zn(PO₃)₂, WO₃ and W₁₈P₂O₅₉. The values of sphere temperature, hemisphere temperature and flow temperature obtained using heating microscopy were strongly influenced by the degree of crystallization process at the sintering.     

Application of Chromium-Containing Silica for Synthesising Functional Glasslike Materials by the Sol–Gel Method

A new variant of the sol–gel method for synthesising silica glasses and optical composites containing nanoparticles of chromium oxide has been designed. Monolithic gels are produced by mixing preformed silica modified with chromium oxide (Cr₂O₃/SiO₂), with a sol–gel solution containing Si(OC₂H₅)₄, and gelation catalyst ((CH₂)₆N₄ or NH₃). Highly dispersed Cr₂O₃/SiO₂ samples were synthesised through a step-by-step controlled adsorption of vapours of CrO₂Cl₂ and C₆H₁₄ on the surface of fumed silica (A-300) and a subsequent thermal decomposition. With increasing chromium concentration in samples from 0.9 to 5.1 wt.%, the size of chromium oxide nanoparticles increases from 10 to 46 nm. XRD, DTA, TG, IR-spectroscopy and measurements of specific surface area have been used to investigate structural and physico-chemical properties of Cr₂O₃/SiO₂ and xerogels during the course of their thermal transformations up to formation of glasses. A study has also been carried out of optical properties of transparent samples (distribution of refractive index values through cross section of a preform). The glasses synthesised with the aid of Cr₂O₃/SiO₂ have a more uniform distribution of doping constituents and exhibit a larger refractive index in comparison to glasses synthesised through impregnation of silica matrices with a solution of (NH₄)₂Cr₂O₇.     

Influence of iron ions on the structural properties of Zn-borosilicate glasses

The effects of iron on the structural properties of Zn-borosilicate glasses have been studied using X-ray diffraction, IR spectroscopy and⁵⁷Fe Mössbauer spectroscopy. Zn-borosilicate glasses were doped with α?Fe₂O₃. In the systems Na₂O?ZnO?B₂O₃?SiO₂?Fe₂O₃ the presence of only one crystalline phase, ZnFe₂O₄, was detected. X-ray diffraction showed that crystallization is more pronounced in the systems ZnO?B₂O₃?SiO₂?Fe₂O₃. In these systems the presence of different crystalline phases, such as ZnO, γ?Fe₂O₃, Fe₃O₄, ZnFe₂O₄ and Fe₃BO₅, was detected. The crystallization of α?Zn₂SiO₄ in the system ZnO?B₂O₃?SiO₂ was confirmed by X-ray diffraction and IR spectroscopy. The valence state and coordination of iron in Zn-borosilicate glasses were determined by⁵⁷Fe Mössbauer spectroscopy.     

Thermodynamic model and structure of CaO–P2O5 glasses

The distribution of Q-units of CaO–P₂O₅ glasses was described by the thermodynamic model of Shakhmatkin and Vedishcheva. The glass was considered as the ideal solution of CaO, P₂O₅, CaP₂O₆, Ca₂P₂O₇, and Ca₃P₂O₈. In the first step, molar Gibbs energies of considered species were taken from the FACT thermodynamic database. The obtained result was compared with ³¹P solid-state NMR study of Roiland. It was shown that the calculated values were in fairly good agreement with the experimental values. After that, the nonlinear regression treatment was used for optimization of molar Gibbs energies by minimizing the sum of squares of deviations between experimental and calculated Q-distribution. In such a manner, the non-ideality of the system was reflected. In the studied case, no significant improvement of obtained results was achieved by this procedure—thus, the ideal solution assumption included in the thermodynamic model of Shakhmatkin and Vedishcheva holds very well for the studied binary glasses.     

Simulation of radioactive decay by barium substitution for cesium in sodium aluminum-iron phosphate glass

Simulation of ¹³⁷Cs radioactive decay to ¹³⁷Ba by an equiatomic substitution of Cs with Ba in a 30 Na₂O, 10 Cs₂O, 10 Al₂O₃, 10 Fe₂O₃, 40 P₂O₅ (mol%) glass was studied by X-ray diffraction, scanning electron microscopy, Fourier Transform Infrared spectroscopy, Mössbauer spectroscopy, and measurement of hydrolytic durability. Gradual Ba substitution for Cs yielded minor changes in the structural network but did not offer appreciable effect on phase composition and hydrolytic durability of the glasses.

     

Gamma irradiation induced photochemical reactions in V-doped borate glasses

Glasses of the composition XNa₂O · 4Al₂O₃ (96-X) B₂O₃ (mole%) where X = 10, 20, 30 to which 0.03 g V₂O₅ per 100 g glass was added, were prepared by normal melting. Their absorption characteristics together with the corresponding V-free base glasses were determined before and after gamma irradiation. The characteristic spectra of the unirradiated glasses show absorption bands at 315, 470, 560–580, 610–650, 700–870, and 860–1000 nm, indicating the presence of vanadium ions in more than one oxidation state, viz, V⁵⁺, V⁴⁺, and V³⁺. Gamma irradation of V-containing glasses causes the formation of color centers in the glass matrices, with absorption bands at 330, 500, and 610 nm, and photoreduced [V³⁺] and [V²⁺] ions with absorption bands at 350–355 and 530–570 and 520 nm, respectively. Photoreduced [V⁴⁺] may also be formed, giving rise to absorptions at 690–700 and 750–800 nm. The induced vanadium ions are found to absorb at shorter wavelengths than the intrinsic ones. An explanation based on the difference in the field energy of the two states is given.