Formation of a glaze coating structure based on low-boron zirconium-containing glass

The structure of initial glasses with 7.5 – 15.0 mol.% of B₂O₃ and glaze coatings based on these glasses is investigated. The initial glasses exhibited a liquation structure. It is established that the primary crystal phase released in heat treatment is anorthite and not the zirconium-containing phase as was observed in glazes with a higher content of B₂O₃. The crystal phases are formed on the basis of liquation drops. Translated from Steklo i Keramika, No. 1, pp. 19 – 22, January, 1999.     

Leucite crystallization from K2O-Al2O3-SiO2 glass-forming melts

It is shown that the K₂O-Al₂O₃-SiO₂ system is promising for obtaining glass ceramic, containing leucite, for fabricating dental prostheses. Glass formation in this system and the crystallizability of glasses, including glasses modified with Li₂O and Na₂O, is studied. The effect of temperature and the time parameters on liquation and crystallization processes is studied.     

Transparent glazes with reduced concentration of B2O3

Na₂O?K₂O?CaO?B₂O₃?Al₂O₃?SiO₂ glasses low in B₂O₃ (14%) and highly resistant to crystallization and liquation under heating are synthesized. They are used for making transparent low-melting heat-resistant glazes with a low boron ion migration rate.     

Oxide ion/electronic polarizability,optical basicity and linear dielectric susceptibility of TeO2 – B2O3 – SiO2 glasses

A system of bio-silica borotellurite glasses was fabricated based on the chemical formula [(TeO₂)_0.7 (B₂O₃)_0.3]_1-x (SiO₂)_x with x = 0.1, 0.2, 0.3, and 0.4 using the melt-quenching technique using silica (98.548% SiO₂, from rice husk), TeO₂ (Alfar Aeser, 99.9%) and B₂O₃ (Alfar Aeser, 99.9%). Measurements and characterizations such as density and molar volume measurements, XRD analysis, FTIR, and UV–Vis spectroscopes were performed on the studied glasses. The objective was to determine the glasses’ applicability in optoelectronics, non-linear optics, and laser technologies through polarizability, linear electric susceptibility, and optical basicity study. Apart from confirming the amorphous nature of the glasses, the XRD analysis identified the presence of a crystalline phase of tellurium oxide (α-TeO₂) formed. The FTIR spectral study revealed the presence of TeO₃, BO₃, and SiO₄ structural units in the studied glasses. The refractive index (2.3026 – 2.2651), molar polarizability (8.0696 – 9.4334 Å³), oxide ion polarizability (3.2970 – 3.6202 Å³), electronic polarizability (0.2296 – 0.2335 Å³), dielectric constant (5.1307 – 5.3019), optical basicity (0.6719 – 0.7998), metallization criterion (0.410853 – 0.420714) and electric susceptibility (0.3286 – 0.3422 esu) of the glasses were presented. With the high refractive index and favourable electronic/oxide ion polarizability as well as good electric susceptibility, the glasses have shown great potential for optical fibre and laser applications. Metallization criterion value falls in the range of glasses with great potentials for non-linear optical application. The dielectric value suggests the glasses represent wideband semiconducting glasses believed to be good for application in microelectronic substrates fabrication.     

Low-Melting Glasses Based on Borate Systems

The results of analyzing systems of low-melting glasses and their application areas based on published data are used to select an optimum system. The melting properties of low-melting glasses based on the borate system ZnO – SrO – B₂O₃ are studied. The dependences of the main properties of glasses (TCLE, softening temperature, microhardness, chemical resistance to water) on their compositions are determined. The optimum low-melting glass compositions with required physicochemical and technological parameters are identified.     

Structural and emission properties of Eu3+‐doped alkaline earth zinc‐phosphate glasses for white LED applications

Quaternary alkaline earth zinc‐phosphate glasses in molar composition (40 ? x)ZnO – 35P₂O₅ – 20RO – 5TiO₂ – xEu₂O₃ (where x=1 and R=Mg, Ca, Sr, and Ba) were prepared by melt quenching technique. These glasses were studied with respect to their thermal, structural, and photoluminescent properties. The maximum value of the glass transition temperature (T_g) was observed for BaO network modifier mixed glass and minimum was observed for MgO network modifier glass. All the glasses were found to be amorphous in nature. The FT‐IR suggested the glasses to be in pyrophosphate structure, which matches with the theoretical estimation of O/P atomic ratio and the maximum depolymerization was observed for glass mixed with BaO network modifier. The intense emission peak was observed at 613 nm (⁵D₀→⁷F₂) under excitation of 392 nm, which matches well with excitation of commercial n‐UV LED chips. The highest emission intensity and quantum efficiency was observed for the glass mixed with BaO network modifier. Based on these results, another set of glass samples was prepared with molar composition (40 ? x)ZnO – 35P₂O₅ – 20BaO – 5TiO₂ – xEu₂O₃ (x=3, 5, 7, and 9) to investigate the optimized emission intensity in these glasses. The glasses exhibited crystalline features along with amorphous nature and a drastic variation in asymmetric ratio at higher concentration (7 and 9 mol%) of Eu₂O₃. The color of emission also shifted from red to reddish orange with increase in the concentration of Eu₂O₃. These glasses are potential candidates to use as a red photoluminsecent component in the field of solid‐state lighting devices.     

Electret Properties of Radiation-Charged Phosphate Glasses

The process of formation of a surface charge in phosphate glasses depending on polarization conditions is investigated. A relationship is established between the chemical composition of glass and its capacity for forming internal electric fields under radiation for glasses of type 0.50P₂O₅ – 0.45RO – 0.05R₂O₃.     

The Effect of Basicity of Glass on Interaction of Variable-Valence Elements

The interaction between two variable-valence elements (As + Fe and As + Cr) simultaneously present in glasses of the four-component system K₂O – B₂O₃ – SiO₂ – Al₂O₃ is investigated. It is demonstrated that as the glass basicity increases, the element to the left of the redox series passes to a higher valence state. Recommendations are issued for correcting concentrations of variable-valence elements for the purpose of optimizing the tint (color shade) in tinted and clear glasses.     

Properties, Structure, and Application of Low-Melting Lead–Bismuth Glasses

Glass formation, crystallization, and physicochemical properties, as well as glass structure in the system PbO – ZnO – Bi₂O₃ – B₂O₃ – SiO₂, are investigated in the section with a constant molar content of glass-formers (B₂O₃ + SiO₂) equal to 20%. A nonlinear dependence of glass properties on their composition is established caused by the change of the coordination state of lead ion in glass structure. The developed glasses are recommended for joint and seals in the production of a new generation of physical parameter sensors.     

Phase Composition and Structure of Aluminum – Coating Composite

Low-melting enamel coatings for household aluminum kitchenware are synthesized. The possibility of formation of low-melting glasses in the system R₂O – Al₂O₃ – B₂O₃ – TiO₂ – P₂O₅ is studied. An optimum glass matrix composition with a decreased firing temperature (580°C) is selected.     

Glazes Based on Liquating Glass Compositions

Liquation glazes with increased whiteness and luster have been developed. The glazes do not contain special opacifying agents. The most intense liquation phenomena in synthesized glasses are registered in the temperature interval of 950 – 1000°C. The glaze coatings obtained are recommended for use in the production of non-food household ceramics and construction ceramics.     

Development of microfibers for bone regeneration based on alkali-free bioactive glasses doped with boron oxide

In this paper, we present a new series of alkali-free bioactive glasses (BG) based on FastOs^® composition (38.49 SiO₂ – 36.07 CaO – 19.24 MgO – 5.61 P₂O₅ – 0.59 CaF₂, expressed in mol %), which was modified by partially replacing silicon dioxide network-former with boron trioxide network-former, utilizing calcium oxide as a charge compensator. The main objective of this study was to obtain a new family of bioactive glasses suitable for the fabrication of glass fibers. The BGs were prepared by melt quenching technique and their structural and thermal properties were determined. Glass rods were used to obtain fibers by the classic drawing technique. The bioactivity of the fibers was subsequently assessed through immersion tests in simulated body fluid (SBF) to establish their ability to form hydroxyl carbonated (HCA) apatite onto their surfaces. Glasses with moderate substitution of SiO₂ with B₂O₃ exhibited enhanced thermal properties, allowing to significantly suppress the crystallization trend, and favoring to draw the fibers. The structure of the studied glasses was obtained by NMR spectroscopy. The structure-property correlations were established by their relationship to the configurational entropy. Smaller amounts of substitution resulted in larger entropy of the glasses. Moreover the SBF tests revealed an extensive formation of HCA, comparable to the parent FastOs^®BG composition, which assures fast bonding to the bone. Thus, presented glass fibers may be considered as promising materials for wool-like bone implants or as reinforcing constituent of biopolymer matrix composites.     

Crystallization Capacity of ZnB2O4 – NaPO3 Glasses

The crystallization capacity of glasses based on the system ZnB₂O₄ – NaPO₃ is investigated. The results of differential-thermal analysis, polythermic analysis, and x-ray phase analysis are described, making it possible to identify the crystallization intervals and the dependence of crystallization on the temperature-time factor.     

Structural heterogeneity of SiO<Subscript>2</Subscript>–Na<Subscript>2</Subscript>O–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> glass

It is shown that the phase heterogeneity of SiO₂–Na₂O–Al₂O₃ glass has a liquation and crystallization nature, the balance between which is determined by the conditions of their synthesis. An increase in the aluminum oxide content decreases the number of liquation and crystallization sites, and also the linear sizes of the crystalline formations without eliminating the phase separation due to the liquation. The area of metastable immiscibility in the SiO₂–Na₂O–Al₂O₃ system, which is determined by scanning electron microscopy, is probably wider than the area detected by the optical methods.     

Allowance for Structural Specifics in a Model of Electric Conductance and Diffusion of Liquating Alkali-Silicate Glasses

Based on the drop model describing the heterogeneous structure of liquating glasses, an integrated expression is obtained for calculating the effective conductivity and the cation diffusion coefficient depending on the overall content of the alkaline oxide. The proposed model agrees with the experimental data for sodium and lithium silicate glasses.     

Tinted Low-Melting Enamels for Aluminum

The possibility of formation of low-melting glasses in the R₂O – RO – Al₂O₃ – B₂O₃ – TiO₂ – P₂O₅ system at a firing temperature of 550°C is investigated. A correlation of glass formation in the considered system with the content of Al₂O₃ and P₂O₅ is established, and the composition of a transition layer with crystalline phases of Na₂O · P₂O₅, Al₂O₃ and Al₂O₃ · P₂O₅ is determined.     

Dependence of the Hydrogen Permeability Coefficient in Glasses of the Sodium-Silicate System on the Silica Modulus

The system Na₂O – SiO₂ used in designing compositions for producing gas microcontainers (microspheres) is investigated. Based on a known equation, an expression is obtained for the dependence of the hydrogen permeability coefficient of glass on its silica modulus. It is established that the alkaline modifier even in the form of an impurity can influence gas permeability. A conclusion is made on the need to apply criterial valuations in designing glasses. A nomogram is obtained for determining the silica modulus, hydrogen permeability coefficient, phase composition, and probability of glass formation in the Na₂O – SiO₂ system.     

Electrochemical Investigation of the Nature of Current Carriers in Sodium Oxyfluoride Glasses

The processes of ion migration in glasses of the NaF–Na₂O–B₂O₃system are studied electrochemically. The results obtained in electrolysis of glass samples in cells with different electrodes are analyzed. The applicability of the known techniques for investigating the nature of current carriers and determining their transport numbers in glasses is discussed. Analysis of the data obtained in electrolysis of the studied glasses in cells with a mercury cathode and anodes prepared from sodium amalgam, metallic silver, and vitreous sodium tetraborate has revealed that protons can participate in the electricity transport processes in addition to sodium and fluorine ions.     

The Effect of Iron Oxides on the Properties and Structure of Glazed Glasses

The effect of iron oxides with a molar content of 2.5 to 35.0% (above 100%) on the properties of aluminoborosilicate glasses is investigated. The specifics of phase separation in iron-bearing glasses and their heat-treatment products and the kinetics of liquation processes are demonstrated. The valence-coordination state of iron ions and the effect of thermal treatment on this state are identified. The dependence of the physicochemical properties of glasses on their chemical composition and structure is considered. The possibility of making colored glaze coating with preset properties and textures is substantiated.     

Pyroelectric composites based on LaBSiO5 stillwellite

Synthesis of ferroelectric materials by glass crystallisation is attractive to produce both high-quality textures and composites. In the present work, composites based on ferroelectric stillwellite-like LaBSiO₅ and glasses having compositions near to compounds Pb₅Ge₃O₁₁, PbLiPO₄ and PbBPO₅ were synthesised and their dielectric and pyroelectric properties examined. A pyroelectric coefficient of about 0.5 nC/cm² K may be obtained by liquid-phase sintering of pellets. Preliminary data on crystallisation processes of the lead-containing glasses as well as on the chemical interactions between stillwellite-like LaBSiO₅ and glasses at the sintering temperature are reported.