Infrared Absorption of Some Alkali Borate and Alkali Silicate Glasses Containing Nickel & Iron Oxides

This work has been carried out to investigate the infrared absorption spectra, of a number of alkali borate and alkali silicate glasses containing nickel oxide and/or iron oxide to investigate the structure of theses glasses. All glasses studied were melted in platinum 2 % rhodium crucibles in an electrically heated furnace at different temperature (1000 – 1400) ⁰C for two hours. The results are explained on the basis that the nickel and ferric ions exist in glass as divalent nickel and trivalent ferric ions respectively in two different states, i.e., octahedral and tetrahedral coordinations.     

Gamma-Ray Shielding Effectiveness of Lead Bismuth Germanoborate Glasses

The gamma-ray shielding effectiveness of the lead bismuth germanoborate glasses has been studied. The mass attenuation coefficients (μ/ρ) of the selected glasses have been obtained through both XCOM program and MCNP5 simulation code. The (μ/ρ) values calculated in both methods are found to be in good agreement and these values are used to calculate effective atomic number, mean free path, half-value layer and energy exposure buildup factors. The shielding effectiveness of these samples has been compared with that of window glasses and some standard shielding concretes. The lower values of mean free path point to the fact that the selected glasses are efficient gamma shields.     

Influence of the melting temperature and rate of cooling the melt to the glass making temperature on the redox equilibria Fe2+ ? Fe3+ and Cu+ ? Cu2+ in aluminum potassium barium phosphate glasses

This paper reports on the results of the investigation of aluminum potassium barium phosphate glasses that contain copper and iron additives and have compositions similar to the composition of the matrix of the KGSS 0180/35 neodymium phosphate glass used for fabricating large-sized active elements intended for high-power laser amplifiers with a high output energy. The redox equilibrium of iron ions has been studied as a function of the melting temperature of the glass (850, 1100, and 1300°C). The redox equilibrium of iron or copper ions and their contributions to the nonactive absorption coefficient of glasses prepared at the melting temperature (1100°C) or after cooling of the glass melt at different rates to the glass making temperature (850°C) have been investigated. It has been established that a decrease in the melting temperature of the glass leads to a shift in the redox equilibrium of iron ions toward the formation of Fe³⁺ ions. During cooling of the glass melt from 1100 to 850°C, the redox equilibrium of copper (iron) ions shifts toward the formation of Cu²⁺ (Fe³⁺) ions; in this case, the lower the rate of cooling the melt, the larger the shift. At the minimum rate of cooling the glass melt (250°C for 180 min), the contribution of copper ions to the nonactive absorption coefficient increases by 25%, whereas the corresponding contribution of iron ions decreases by 40%.     

Conductive and Radiative Properties of Soda‐Lime Silicate Glassmelts with Different Iron Contents from 1100°C to 1500°C

This paper presents an inverse method for retrieving (i) the true thermal conductivity, and (ii) the two‐band absorption coefficient of soda‐lime silicate glassmelts between 1100°C and 1550°C from measured steady‐state temperature profiles. This was achieved by combining (i) a forward method solving combined conductive and radiative heat transfer accounting for temperature‐dependent thermal conductivity and spectral absorption coefficient and (ii) an inverse method based on genetic algorithm (GA) optimization. Four glassmelt compositions from ultraclear to gray glasses with iron content ranging from 0.008 to 1.1 wt% were investigated. First, it was established that the steady‐state temperature in glassmelt can be predicted accurately by averaging the spectral absorption coefficient over two bands from 0 to 2.8 μm and 2.8 to 5.0 μm. The inverse method showed that the true thermal conductivity was independent of the iron content and given by k_c(T) = 1.31 + 5.90 × 10^?4T, where T is given in °C. In addition, the band absorption coefficient between 0 and 2.8 μm strongly increased with increasing iron content, while the band absorption coefficient between 2.8–5.0 μm was independent of iron content.     

Characterisation of glasses in the TeO2–WO3–PbO system

As potential candidates for photonic devices, non-linear materials and coatings, 22 glasses in the TeO₂–WO₃–PbO system have been formulated and prepared by conventional melting at temperatures ranging between 710 and 750 °C. The glass forming area has been determined for a wide region of the corresponding ternary diagram. Structural characterisation of the glasses was conducted through FTIR spectrometry and the variation of density values, which allowed calculation of the glass molar volume and the oxygen molar volume. UV–VIS spectra were recorded to determine optical absorption/transmission and energy gap values. Likewise, such results were correlated with the glasses composition and their ability for optical materials. DTA curves yielded data of transition temperature (T_g), onset crystallisation temperature (T_c) and the thermal stability range of glasses. Crystalline phases formed in devitrified and partially devitrified glasses were detected by X-ray diffraction. The properties and structural features of glasses were discussed in terms of their relative proportion of former/modifier oxides. The main glass former oxide is TeO₂, which arranges [TeO₄] groups with tetrahedral coordination, while PbO plays as glass modifier oxide. Tungsten oxide is incorporated as network former, alternating with TeO₂ and forming mixed linkages Te–O–W and W–O–W. WO₃ is the component that contributes most to increase the glass transition temperature, and to decrease both the oxygen molar volume and the thermal expansion coefficient.     

The radiation-shielding properties of ternary SiO2–SnO–SnF2 glasses: Simulation and theoretical study

In this study, the shielding capabilities of five selected glasses with a (100-x) SiO₂-x(SnO + SnF₂) chemical composition (x = 40, 45, 50, 55 and 60 mol%) have been investigated. The mass attenuation coefficient values were simulated using the MCNP5 Monte Carlo code, while the results were confirmed theoretically by the online version of the XCOM program. Based on the obtained mass attenuation coefficient values, effective shielding parameters such as linear attenuation coefficient, half value layer, mean free path, effective atomic number, and electron densities have been calculated. Exposure and energy absorption buildup factors have also been calculated. Glass shielding capabilities against neutrons has been investigated by calculating the fast neutron removal cross section. The results reveal that an increase in the SnO ratio in the glass composition leads to an increase in the attenuation properties: the investigated glasses are superior as shields against gamma radiation.     

Yb:Niobosilicate Glass with High-Emission Cross Section

The emission cross section for the ² F _5/2–² F _7/2 transition of Yb³⁺ has been determined from absorption and emission measurements of niobosilicate glasses at room temperature. Using systematic variations in the spectroscopic properties, relative to composition, a glass host with emission cross sections of >2.00 pm² and fluorescence lifetimes of >0.8 ms is obtained. This glass has advantages over some laser glasses that have been reported in other published papers.     

Effect of coloring impurities on the absorption in neodymium phosphate laser glass at a lasing wavelength

This paper reports on the results of the investigation of KGSS 0180/35 neodymium phosphate glasses produced on an industrial scale under oxidizing conditions and glasses prepared under experimental conditions in which iron and copper in small amounts rather than neodymium are introduced into the glass composition. The experimental glasses are synthesized by varying the redox conditions of melting. The oxidation states of transition metal impurities (Cu, Fe, V, Ni, Co) and the nonactive absorption coefficients of glasses at the lasing wavelength are determined. It is revealed that the main contribution to the nonactive absorption coefficient of the KGSS 0180/35 glass produced on an industrial scale is made by Cu²⁺ ions at a concentration higher than 0.5 ppm. At a lower copper concentrations, the total contribution of Fe²⁺, V⁴⁺, Ni²⁺, and Co²⁺ impurity ions to the nonactive absorption coefficient is comparable to that of Cu²⁺ ions. It is demonstrated that a decrease in the concentration of coloring impurities in glasses and the optimization of redox conditions of melting make it possible to prepare phosphate laser glasses with a nonactive absorption coefficient of the order of 0.001 cm^?1. In terms of the nonactive absorption coefficient, these glasses are on a par with similar glasses of foreign manufacture and satisfy the requirements imposed on glasses by developers of high-power high-energy laser facilities.     

EXPERIMENTAL STUDIES OF THE TEMPERATURE GRADIENTS IN GLASSES OF VARIOUS COLORS*

Laboratory gradients are presented for glasses of different colors and coloring agents when heated at the surface to a temperature of 2615°F. The gradients in commercial tanks are related to these laboratory-tank experiments. Ferrous iron and chromic oxide yield the largest gradients, whereas selenium, cerium, and very small amounts of cobalt give small gradients. Ferric iron gives a largc gradient and manganese a relatively low gradient. Iron sulfur ambers are intermediate. Visible color or color intensity is no indication of the temperature gradients.     

EFFECT OF IRON OXIDE ON PROPERTIES OF SODA-DOLOMITE LIME-SILICA GLASS*

In two base glasses, the first containing 16% of sodium oxide, 10% of dolomite lime, and 74% of silica, and the second with 14% of sodium oxide, 12% of dolomite lime, and 74% of silica, iron oxide was systematically substituted for (a) Na₂O, (b) CaO·MgO, and (c) SiO₂ in amounts of 1, 3, and 5%. The effects of these substitutions on such properties as liquidus temperature, viscosity, deformation temperature, fiber softening point, density, coefficient of expansion, and the resistance of the glasses to dilute acid and distilled water, arc presented.     

Total Heat-Transmission Coefficients of Amber and Green Glasses in Temperatures of Melting Range

Measurements of an over-all heat-transmission coefficient for several commercial amber glasses were carried out in a pilot-scale furnace at temperatures of the melting range. The data obtained were used in deciding depth and insulation of tank furnaces. It appears that the transmission of light of amber glasses in the near-infrared range gives a practical indication of these heat-transmission properties. The same pilot-scale furnace was used to investigate the effect of chromium oxide, nickel oxide, and iron oxide on the over-all heat-transmission coefficients of green glasses. An empirical equation was derived, relating the heat-transmission coefficient to the concentration of the coloring oxides. Of the three oxides, the effect of the nickel oxide on heat transmission is the strongest and the effect of the iron oxide is the weakest.     

Determination of OH Extinction Coefficients in R2O-B2O3-SiO2 Glasses (R = Li, Na, K)

Infrared spectra of glasses of the system R₂O-B₂O₃-SiO₂ were investigated. The extinction coefficients of the hydroxyl absorption band ("free OH") were calculated by a method proposed for alkali borate glasses. The results confirmed the applicability of this method to homogeneous and phase-separated alkali borosilicate glasses. The variation of the hydroxyl absorption band position was interpreted according to the structural characteristics of the studied glasses.     

EFFECT OF COMPOSITION AND TEMPERATURE ON SOLUBILITY OF IRON OXIDE IN GROUND-COAT ENAMEL GLASS*

The solubility of iron oxide in ground-coat enamel glasses at various temperatures was studied by adding varying amounts of ferric oxide to the milled enamel and giving the mixture a heat-treatment to acquire uniformity without devitrification at the desired temperature. The iron oxide solubility was obtained by finding the breaking point in the curve for iron oxide versus index of refraction. The frit solubilities were obtained at 1400°, 1600°, 1800°, and 2000°F. with variations in Na₂O, B₂O₃, A1₂O₃, CaF₂, CaO, F₂, SiO₂, COO, NiO, MnO₂, BaO, and MoO₃. Data are given on a number of commercial frits.     

Thermal Conductivity: XII, Temperature Dependence of Conductivity for Single-Phase Ceramics

Theoretical relationships and experimental data concerning thermal conductivity for a number of oxide materials have been compared over a wide temperature range. Deviations from the basic proportionality between k and 1/ T are caused by radiant-energy transmission, a high Debye temperature, a low mean free path of the thermoelastic waves, porosity, and in a few cases electronic conductivity. Extrapolation of thermal conductivity data to high temperatures is not reliable.     

THE USE OF BORIC OXIDE IN GLASS-MAKING

Boric oxide behaves differently from other glass-making constituents in that the variation of physical properties is not progressively continuous with a variation in composition. With increase of boric oxide content in sodium borosilicate glasses, the refractive index (μ_D) rises to a maximum as also does the annealing temperature, while the coefficient of thermal expansion reaches a minimum and then rises. The durability, or resistance to water and hydrochloric acid reaches a maximum when the glass contains about 12% of boric oxide and subsequently falls off very rapidly. There is, accordingly, a limit to the usefulness of boric oxide in glass.     

High-Temperature Integral Absorption in Glasses

The information published in various sources concerning IR absorption of certain glasses is summarized. The results are supplemented by the data of research carried out by the authors. It is proposed to use the integral absorption coefficient calculated for the considered glass compositions in solving the problems of radiation-conductive heat exchange. The resulting data bank will make it possible to predict the integral absorption of glasses containing certain transition elements, primarily, iron.     

Thermal properties of ecological phosphate and silicate glasses

The present work deals with ecological phosphate and silicate glasses that belong to the oxide systems: Li₂O-MgO-P₂O₅, Li₂O-CaO-P₂O₅, Li₂O-MgO-P₂O₅-Fe₂O₃; Li₂O-CaO-P₂O₅-Fe₂O₃ and SiO₂-R₂O-R′O (R = Na, K; R′ = Mg, Ca), the last system contains certain amounts of ZrO₂, ZnO, TiO₂. These ecological glasses do not contain toxic substances as BaO, PbO, As₂O₃, As₂O₅, fluorine, CdS, CdSe and they have applications as regards the retention and counteracting action of the harmful compounds resulted from the nuclear plants. The replacement of MgO by CaO leads to an insignificant increasing of the thermal expansion index and a slight decreasing of the characteristic temperatures, except the softening point where the effect is opposite. Adding of iron oxide in the phosphate glass composition causes the increasing of characteristic temperatures and the decreasing of thermal expansion index, both in MgO and CaO-containing phosphate glasses. The ecological silicate glasses are used as opal glasses free of fluorine as well as for lead-free crystal glass (CFP) where BaO and PbO are replaced by non-toxic oxides as K₂O, MgO, ZrO₂, and TiO₂. The paper presents different glass compositions and the technological parameters to prepare the ecological glass samples. Both ecological phosphate and silicate glasses have been characterized as regards the characteristic temperatures (vitreous transition point, low and high annealing points, softening point) and the thermal expansion coefficient. This study presents the changes of the thermal parameters when CaO replaces MgO in phosphate glass samples and the role of iron oxide in the vitreous network. In the case of silicate glasses, the viscosity and wetting angle dependency of temperature are presented. The elemental analysis of the ecological glasses was made by XPS (X-ray photoelectron spectroscopy) which also put in evidence the iron species from the vitreous network.     

Infrared Spectroscopic Method for Determination of Thermal Properties of Fluorophosphate Glasses

Fluorophosphate glasses of the Ba(PO₃)₂–MgF₂–CaF₂–AlF₃ system exhibit anomalous behavior, in regard to the glass-transition temperature ( T _g) and the coefficient of thermal expansion (α_CTE), at a fluoride concentration of ∼36 mol%. A similar trend in the infrared band absorption coefficient (α_IR) at 2170 cm⁻¹ of the overtone of 2ν_ss(OPO) and/or a combination of ν_as(OPO)+ν_as(POP) fundamental vibrations of PO₄ tetrahedra also has been observed, relative to changes in the glass composition. Statistical analyses have shown that the T _g and α_CTE values are correlated with α_IR at 2170 cm⁻¹ by linear equations. The thermal properties of some of the glasses have been calculated using these equations, to test their validity and utility. The experimental property values of the glasses present a very good fit of data within a 95% confidence interval of the calculated mean values.     

高纯钛氧化物中微量铁的萃取分光光度测定

利用二氯乙烷萃取邻二氮菲－铁（Ⅱ）－苦味酸盐三元配合物,可以藉分光光度法测定钛氧化物中的微量铁,表观摩尔吸光系数达１．２２×１０５。方法灵敏、干扰少,已用于高纯钛氧化物中微量铁的测定。     

Vibrational Spectra of Vitreous B2O3.xH2O

The infrared absorption spectra of boron oxide glasses of low and high water content have been obtained in the 400- to 4000-cm.⁻¹ region using thin films or fine powders dispersed in a liquid. A structural interpretation of the glass spectra has been made with the aid of the spectra of the closely related materials boric acid, orthorhombic metaboric acid, and partly deuterated boron oxide glass of high water content. It has been shown that the glass spectra are consistent with a random-network structure in which each boron is triangularly coordinated by three oxygens and that the presence of water leads to weak hydrogen bonding between oxygen atoms. No evidence for a substantial amount of tetrahedral coordination of boron by oxygen has been found in glasses of either low or high water content.