Mixed Alkaline Earth Effect Research Articles

Effect of different Ba/Sr ratios on the properties of borosilicate glasses for application in 3D packaging

Borosilicate glass is a promising material for 3D system integration technology due to its high integration and adjustable CTE (coefficient of thermal expansion). However, the structure and composition of borosilicate glasses result in a relatively high melting point and dielectric loss, which hinders the wide application of such glasses. In this study, we analyze the relationship between different Ba/Sr ratios and the structure and properties of the glass. We determine and further analyze the effect of mixed alkaline earth effect on the proportion of the Qn unit, [BO3], and [SiO4] in the glass structure, and consequently, its influence on the dielectric properties. Alkaline earth metals act as network-modifying ions to reconnect the interrupted network of the glass, stabilizing the glass structure and reducing the polarization loss of the glass. Raman analysis showed that the Raman spectrum shifted towards higher frequencies as the ratio of Al2O3/RO increased, with the Raman bands at 1300 cm−1-1500 cm−1 almost disappearing, while the Raman area at 730 cm−1-830 cm−1 increased. This indicated that the [BO3] units formed a ring structure in the glass, thereby enhancing the compactness of the glass network. The thermal expansion coefficient was 4.09 ppm K−1 when the Ba/Sr ratio was 1:1, and the dielectric constant and dielectric loss were 4.3 and 1.24 × 10−3, respectively. Overall, the dielectric properties and thermal expansion coefficients of the glass can be effectively reduced by doping with alkaline-earth metals, making the borosilicate glass more suitable for three-dimensional integrated system packaging.

Structural and performance variations of aluminoborosilicate glass substrates with mixed alkaline earth effect for applications in 3D integrated packaging

Alkali-free aluminoborosilicate glass substrates possess excellent chemical stability and outstanding thermodynamic and dielectric properties, rendering them promising candidates for applications in three-dimensional integrated packaging. This study investigates the structural and performance variations in RO (RBa,Sr)–Al2O3–B2O3–SiO2 glass substrates with a mixed alkaline earth effect under different BaO/SrO ratios (with a constant RO value of 20 mol%). The glass substrates were analyzed using various methods, including X-ray diffraction, differential scanning calorimetry, coefficient of thermal expansion, Raman spectroscopy, and 1 MHz–1 GHz dielectric property tests. Raman spectroscopy was used to measure the glass network connectivity using R12/34 (degree of [SiO4] units depolymerization) and N4 (degree of [BO4] units polymerization). The results show that the RABS15 sample had a significant reduction in dielectric loss at a frequency of 1 GHz compared with the other glass samples, corresponding to the best glass network connectivity. The main cause of high-frequency dielectric loss was the presence of [BO3] units in the glass network. During the preparation process, it was discovered that placing the crucible with mixed raw materials in an elevator-type furnace at a high temperature is an effective measure for solving the crystallization problem.

Effect of MgO addition on the structural evolution, crystallization and properties of self-glazed ceramics sintered from granite sludge

Recycling of granite sludge has both economic and environmental benefits. In this paper, high glossiness self-glazed ceramics were prepared from granite sludge with the addition of TiO2, Ca(OH)2 and MgO by combining two-step sintering and low-temperature crystallization. The effect of MgO addition on the phase evolution, crystallization and properties of the glazed ceramics was studied to reveal its role in the diopside precipitation. With increasing MgO content, the reduced glass viscosity accelerates the dissolution of quartz and anorthite into the liquid glass phase, resulting in a decrease in flexural strength above 1 % MgO. Meanwhile, the addition of MgO increases the non-bridging oxygen to lower the glass transition temperature. The increase in the Al/Si ratio of the glass phase and the mixed alkaline earth effect contribute to an increase in the crystallization temperature. After thermal treatment at 950 °C, the precipitated diopside increases the crystallinity of the glazed glass-ceramic from 6.4 % to 19.3 % at 3 % MgO, resulting in a surface glossiness of 99.7 GU and a flexural strength of 64.1 MPa. High glossiness self-glazed ceramics with an aesthetic appearance could be used in decorative building tiles for scalable utilization of granite sludge.

Mixed-alkaline earth effects on the network structure and properties of alkali-free aluminosilicate glasses

Alkali-free aluminosilicate glasses with different SrO/(MgO+SrO) molar ratios were prepared by the melt-quenching method, and their structural evolution was characterized by Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR). The glass properties, including high-temperature viscosity, thermal expansion coefficient, density, Vicker hardness, elastic modulus, and chemical stability, were tested and analyzed. With the increasing of SrO/(MgO+SrO) molar ratios from 0 to1, the fraction of Q4 units in [SiO4] tetrahedral increased from 30.88 % to 39.06 %, and the Al3+ ions are dominated in [AlO4] groups, but small amount in [AlO5] units. In terms of comprehensive properties, the glass density and strain point temperature increased approximately linearly with the SrO/(MgO+SrO) ratios, while, the elastic modulus decreased with the SrO/(MgO+SrO) ratios. However, the high-temperature viscosity, Vickers hardness, chemical stability, and characteristic temperatures (melting temperature, working point temperature, Littleton softening temperature) deviated from linearity and exhibited the opposite mixed alkaline earth effect compared to previously reported aluminosilicate glasses. when the SrO/(MgO+SrO) molar ratio is approximately 0.25, the glass demonstrates optimal comprehensive performance.

Mixed alkaline earth effect on nanomechanical properties of glass

The mixed alkaline earth effect (MAEE) on the mechanical behavior of oxide glasses have received significant attention of glass scientists. In this study, we unveiled the MAEE on the nanomechanical properties of a boroaluminosilicate (BAS) glass series with the varying molar ratios of R=[MgO]/([MgO]+[CaO]), through a combination of nanoindentation, nanoscratch, and nanowear tests. The MAEE was observed as positive deviations from the linear trend in nanohardness and reduced modulus with varying R. On the contrary, the MAEE manifested as negative deviations from the linear trend in nanoscratch depth, nanoscratch residual depth, nanowear volume, and volume densified by nanowear. The maximum and minimum values were observed at R = 0.56. The MAEE on nanowear behavior was found to be mainly governed by the nano-indentation and subsurface densification. These discoveries provide valuable insights into the nanomechanical properties of glass surfaces, contributing to the development of advanced glasses with improved mechanical properties and extended lifespans.

Mixed alkaline earth effect on the structure and elastic modulus of CaO–MgO–Al2O3–SiO2 glasses: A molecular dynamics simulation

The influence of mixed alkaline earth effect on the atomic structure and elastic modulus of the CaO–MgO–Al2O3–SiO2 glasses were studied by molecular dynamics simulation. The elastic modulus values obtained from the simulation of uniaxial tension and stiffness tensor methods showed the same trend with the change of composition, while the simulated results of the former were closer to the measured data. The variation trend of Qn species obtained by the simulation and Raman spectroscopy was consistent. Ca and Mg cations were more inclined to form non-bridging oxygen when the Ca/Mg ratio exceeded 1, which damaged the tetrahedral connection and further reduced the degree of network polymerization. The ratio of non-bridging oxygen to tetrahedrally coordinated cations (NBO/T) used to characterize the degree of polymerization was found to have a linear relationship with the elastic modulus. In addition, the local cluster of modifier atoms was beneficial to increase the elastic modulus values.

Elastic Properties and Hardness of Mixed Alkaline Earth Silicate Oxynitride Glasses.

The incorporation of nitrogen as a second anion species into oxide glasses offers unique opportunities for modifying glass properties via changes in glass polymerization and structure. In this work, the compositional dependence of elastic properties and the nanoindentation hardness of mixed alkaline-earth silicate oxynitride glasses containing a high amount of nitrogen (>15 at.%, c.a. 35 e/o) were investigated. Three series of silicon oxynitride glass compositions AE–Ca–Si–O–N glasses (where AE = Mg, Sr, and Ba) having varying amounts of modifiers were prepared using a new glass synthesis route, in which a precursor powder of metal hydrides was used. The obtained glasses contained high amounts of N (19 at.%, c.a. 43 e/o) and modifier cations (26 at.%, c.a. 39 e/o). Mg–Ca–Si–O–N glasses had high values of nanohardness (12–16 GPa), along with a reduced elastic modulus (130–153 GPa) and Young’s modulus (127–146 GPa), in comparison with the Sr–Ca- and Ba–Ca-bearing oxynitride glasses. Both the elastic modulus and the nanohardness of AE–Ca–Si–O–N glasses decreased with an increase in the atomic number of the AE element. These property changes followed a linear dependence on the effective cation field strength (ECFS) of the alkaline earth (AE) modifier, according to their valences and ionic radii. No mixed alkaline-earth effect was observed in the current investigation, indicating that the properties were more dictated by the nitrogen content.

Analysis of unconventional boron-aluminum anomaly induced by mixed alkaline earth effect in glass substrate

In this paper, the alkali-free aluminoborosilicate glass substrate was successfully prepared by the traditional melt quenching method, and the effect of boron oxide replacing alumina on the structure and properties of glass substrate was studied. DSC, FTIR and XPS results were used to analyze the physical-chemical properties and thermal properties of the materials in detail. The results show that when boron oxide replaces alumina to 8 wt%, unconventional boron-aluminum anomaly (aluminum oxide tetrahedron was increased to 97.67%, and the boroxy tetrahedron appeared with a relative content of boroxide triangulation of 21.14%) leads to a more stable structure of glass network and extreme performance. This phenomenon is caused by the mixed alkaline earth effect resulting from the change in the ratio of alkaline earth metal oxides. In this study, most of the properties of glass have met industrial standards, and the theoretical analysis has reference significance for industrial production.

Research on mixed alkaline-earth effect in non-alkali glass substrates for TFT-LCDs

Herein, we used CaO to replace MgO to investigate the effect of mixed alkaline-earth effect on structure and properties of the non-alkali glass substrates which were synthesized by the traditional melting technology. The results show that with the replacement of CaO for MgO, the stability of the glass network structure decreases due to the decrease of the bridging oxygens. In terms of the comprehensive properties, the glass density, molar volume, thermal expansion coefficient, strain and softening points, and chemical stability all show a near-linear increase or decrease. However, due to the mixed alkaline-earth effect, some other properties including the crystallization peak temperature, thermal stability, and mechanical properties show a negative deviation from linearity, and the extremum locates at the CaO content of 6 mol%. Based on the results, this research can provide a significant guidance for the property control of non-alkali glass substrates.

Chemical durability of borosilicate pharmaceutical glasses: Mixed alkaline earth effect with varying [MgO]/[CaO] ratio

AbstractGlass for pharmaceutical packaging requires high chemical durability for the safe storage and distribution of newly developed medicines. In borosilicate pharmaceutical glasses which typically contain a mixture of different modifier ions (alkali or alkaline earth), the dependence of the chemical durability on alkaline earth oxide concentrations is not well understood. Here, we have designed a series of borosilicate glasses with systematic substitutions of CaO with MgO while keeping their total concentrations at 13 mol% and a fixed Na2O concentration of 12.7 mol%. We used these glasses to investigate the influence of R = [MgO]/([MgO] + [CaO]) on the resistance to aqueous corrosion at 80°C for 40 days. It was found that this type of borosilicate glass undergoes both leaching of modifier ions through an ion exchange process and etching of the glass network, leading to dissolution of the glass surface. Based on the concentration analysis of the Si and B species dissolved into the solution phase, the dissolved layer thickness was found to increase from ~100 to ~170 nm as R increases from 0 to 1. The depth profiling analysis of the glasses retrieved from the solution showed that the concentration of modifier ions (Na+, Ca2+, and Mg2+) at the interface between the solution and the corroded glass surface decreased to around 40%–60% of the corresponding bulk concentrations, regardless of R and the leaching of modifier cations resulted in a silica‐rich layer in the surface. The leaching of Ca2+ and Mg2+ ions occurred within ~50 and <25 nm, respectively, from the glass surface and this thickness was not a strong function of R. The leaching of Na+ ions varied monotonically; the thickness of the Na+ depletion layer increased from ~100 nm at R = 0 to ~200 nm at R = 1. Vibrational spectroscopy analysis suggested that the partial depletion of the ions may have caused some degree of the network re‐arrangement or re‐polymerization in the corroded layer. Overall, these results suggested that for the borosilicate glass, replacing [CaO] with [MgO] deteriorates the chemical durability in aqueous solution.

The fiber spinnability and mixed alkaline effect for calcium magnesium aluminosilicate glasses

In this paper, we discussed the fiber spinnability and mixed alkaline earth effect in the aluminosilicate glasses with MgO replaced by CaO. The high-temperature viscosity, dilatometric and DSC tests were applied. Results show that Kfib shows the opposite results to that from the graphical map of (m:D), while the ΔT only picks one glass sample for fiberizing. The mixed alkaline earth effect manifests itself as minima in viscosity, and characteristic temperatures, but maxima in fragility, thermal expansion, which are related to the increased entropy, the loose network, and weak bonds, not the network connectivity. The lower values for Mg end-member would be attributed to the higher field strength that would attract the nearest oxygen and cause more disturbance to the glass structure. The free volume is not related to the mixed effects in the viscosity and characteristic temperatures but should have a relationship with the melt strength index.

The influence of the mixed alkaline earth effect on the structure and properties of (Ca, Mg)–Si–Al–O–N glasses

Alkaline earth oxynitride glasses of (Ca, Mg)–Si–Al–O–N with different CaO/(CaO + MgO) molar ratios (0, 0.25, 0.5, 0.75, and 1) were successfully prepared using the sol-gel method, and their structural compositions were characterised by Raman and FT-IR techniques. The glass dynamic properties of thermal expansion coefficient, glass transition temperature (Tg), and static properties of density, molar volume, Vickers hardness and compressive strength were systematically measured and analysed. The results showed that the static properties exhibited an overall regular change as the CaO/(CaO + MgO) ratio gradually increased, while the dynamic properties had an obvious mixed alkaline earth effect, which represented the appearance of an extreme value point in CaO/(CaO + MgO) mole ratios of 0.25 and 0.75, respectively. The typical thermal expansion coefficient and Tg of mixed alkaline earth oxynitride glasses deviated far from the linear connection between single alkaline earth oxynitride glasses. Raman spectra and infrared spectra revealed that the ratio value of the Q3/(Q2+Q4) decreased (Qn: n = no. of bridging anions joining SiO4 tetrahedra) in the mixed alkaline earth oxynitride glasses with increasing the amount of Ca, confirming that Ca decreased the crosslinking between individual tetrahedra via the transformation of Q3 species into Q2 and Q4 species.

Progress in modeling of glass properties using topological constraint theory

AbstractPrediction of glass properties as a function of composition has been a long‐standing problem. Topological constraint theory has built the quantitative relationships between composition and macroscopic properties, which can be used to predict compositional dependence of glass properties. In this review, we will summarize the recent important progress for the development of the theory. The topological model for glass transition temperature has been proposed from temperature‐dependent constraint theory. We will also discuss the effect of water on topological constraint, how to account for mixed alkali effect and mixed alkaline earth effect, and the application of the model to new glass family besides inorganic glasses. Topological models for hardness and thermal expansion have also been developed. Topological models for predicting elasticity have been recently proposed. We also show some example on the application of the theory in designing new glasses and we suggest some future directions of the theory.

Understanding how the mixed alkaline-earth effect tunes transition metal oxides-tellurite glasses properties

Mixed alkaline-earth effect (MAEE) on the transition metal oxides (TMO)-tellurite glasses [TMO = MoO3, Nb2O5 and WO3] modified with BaO/MgO mix is analyzed to understand how feasible it is to tune structural and optical properties of a tellurite glass. Changes induced by the three transition metal oxides on the tellurite polyhedral produce some modifications on the cut-off wavelength, optical band gap, Urbach's energy, refractive index and permittivity values where the MAEE manifest itself in different ways. The changes in the glass structural properties are dominated by the TMO type while optical and electrical properties depend mostly on the combination between the TMO and the [BaO/(BaO + MgO)] ratio. Glass transition temperature is discussed in terms of some parameters like number of bonds per unit volume, average stretching force constant, molar volume, oxygen packing density values (OPD) and FTIR spectra. In this work we provide evidence that the behavior attributed to the relationship between structure and electrical or optical properties in pure oxide and even binary systems is not reproduced by multi-component glassy systems. A comparison between traditional and new optical methods confirm allowed direct inter-band electronic transitions in the studied glasses evidencing that the a priori parameter election is not always an accurate procedure.

Topological understanding of the mixed alkaline earth effect in glass

The mixed alkaline earth effect (MAEE) is important for several families of industrial borosilicate and aluminosilicate glasses, including glasses used in pharmaceutical packaging and as substrates for flat panel displays. Despite the technological importance of the mixed alkaline earth effect, the physical origin of this phenomenon is not well understood, and there is currently no model to offer quantitative prediction of the effect. In this work, the MAEE is studied both experimentally and through modeling in a series of boroaluminosilicate glasses with systematic substitution of CaO with MgO. The network structure is characterized by magic angle spinning nuclear magnetic resonance (MAS NMR) analyses of 27Al, 11B, 29Si, and 23Na. Molecular dynamics (MD) simulations are conducted to simulate the glass structures and calculate the evolution of the bond angle distributions with composition. Based on the structural data, a topological constraint model is proposed to capture the MAEE on glass transition temperature (Tg), liquid fragility index (m), and Young's modulus (E) of the glasses. Results of the topological constraint model are in good quantitative agreement with experimental data. The success of the constraint model confirms that the mixed alkaline earth effect is the result of a shift in angle around oxygen in the cation-oxygen-cation bond in the glass network. This is related to the constraint strength that ultimately governs the nonlinear property variation.

Mixed alkali/alkaline earth‐silicate glasses: Physical properties and structure by vibrational spectroscopy

AbstractIn this article, we investigate the correlation of selected physical properties with structural changes in quaternary mixed modifier alkali/alkaline earth oxide silicate glass systems, focusing either on the mixed alkali effect [(20−x)Na2O–xK2O–10CaO–70SiO2 (x = 0, 5, 10, 15, 20)] or on the mixed alkaline earth effect [20Na2O–(10−y)CaO–yBaO–70SiO2 (y = 0, 5, 10)]. A maximum microhardness and packing density, as well as a minimum glass transition temperature were observed for mixed alkali glasses. The mixed alkaline earth glasses do not exhibit any clear extrema in any of the properties studied. The hardness and glass transition temperature decreases, while the density and molar volume increases with increasing BaO content. Raman spectroscopy showed an increase in the Q3 group compared to the Q2 and Q4 groups as the high field strength ions Na+ or Ca2+ are substituted by their low field strength analogs K+ or Ba2+. In the mixed alkali series, the high field strength ion Na+, seems to push the low field strength ion K+ into lower energy sites when present simultaneously, while such an effect is not apparent for the mixed alkaline earth glasses, where the far IR spectra of mixed glasses are equivalent to the weighted averages of the pure glasses.

Mixed intermediate effect on mechanical and rheological performances in Zn[sbnd]Mg silicate glasses

In contrast to the mixed alkali or mixed alkaline earth effect, the mixed intermediate effect has received little attention in glass community. Here, we focus on the mixed intermediate effects, i.e. mixed MgZn effects, by partial substitution of MgO for ZnO in sodium silicate glassy series. Opposite to the previously reported “mixed alkaline earth effects”, here the compositional dependences of microhardness and isokom temperature following the gradual substitution of Mg by Zn show a positive deviation from the linear tendency between the two end-members, which is maybe due to the competition between cationic potential energy mismatch and network polymerization. Through the structural identification by Raman scattering technique, we give a microscopic explanation for the observed mixed MgZn effects. Finally, we identified the mixed MgZn effects on viscosity and configurational entropy, which indicates that the Zn and Mg have a similar dynamic role at glass transition temperature but play a more different role at lower viscosity.

Homogeneity of modifier ion distributions and the mixed alkaline earth effect in MgO–CaO–SiO2 silicate glasses using molecular dynamics

Oxide glasses containing a mixture of modifier ions have a wide range of applications, and it is often assumed that these modifier ions mix homogenously in the melt. Silicate glasses are known for their significant industrial importance and are often doped with magnesium and calcium modifier ions to utilise their properties for applications. This study investigated the structural and dynamical impact imposed on a glass by the presence of two different types of alkaline earth cations. This was achieved through increasingly substituting magnesium for calcium in xMgO–(50–x)CaO–50SiO2 glasses which were modelled computationally using classical molecular dynamics simulation (MD). A mixed alkaline earth effect (MAEE) was found to cause the suppression of the modifier ion diffusivity. An absence of any significant deviation from the expected trends in the structural investigations confirmed that the MAEE is not a structural effect. This MAEE was therefore analogous to the mixed alkali effect (MAE), and was most prominent for roughly equimolar mixtures of calcium and magnesium ions. Interestingly, there was also evidence of the diffusivity being enhanced when only a small amount of a second alkaline earth ion was added.

The mixed modifier effect in ionic conductivity and mechanical properties for xMgO-(50-x)CaO-50SiO2 glasses

The mixed-modifier effect (MME), i.e., the tendency of the physical properties of a glass to deviate from the law of additivity when multiple network-modifying components are included, can cause large improvements in the mechanical properties of glasses. However, previous studies of the MME have been largely limited to systems containing alkali metal modifiers, and the origins of the MME for mechanical properties remain unclear. Here, a series of glasses with purely mixed alkaline earth modifiers, xMgO-(50−x)CaO-50SiO2, and prepared and used to verify the existence of the mixed-alkaline-earth effect (MAEE) in ionic conductivity and mechanical properties. While the deviations from linearity for the MAEE were not as large as is typical for the mixed-alkali effect (MAE), they were still significant (up to 30%). Unexpectedly, the ionic conduction in these glasses was found to deviate significantly from Arrhenius behaviour, with the activation energy decreasing at elevated temperature. Examination of the MME in mechanical properties showed that the activation energy for ion conduction was correlated with shear stiffness, but not compressibility, indicating that the shear modulus may serve as a reasonable predictor of the strain energy required for ion hopping during conduction. The connectivity of the glass network, as determined by Raman spectroscopic analysis, was used to relate the MME in static properties and dynamic properties.

A new transition metal-tellurite glass family: Electrical and structural properties

Glasses of composition 0.8 [xBaO.(1−x)MgO]. 0.2TM.2TeO2 with TM: MoO3, WO3, V2O5 or Nb2O5 (x=mol content) were obtained by the melt quenching technique. Raman Spectroscopy, Density and Differential Scanning Calorimetry were used to infer their microscopic structure and electrical properties were studied using Impedance Spectroscopy. Some singularities in their electrical and structural properties appeared. Deviations from linearity as a function of alkaline-earth oxide modifier content were observed both on the electrical and structural properties. They were analyzed considering the intensity of the electrical field of the mix of alkaline earth cations which induced changes on the glassy matrix and the mixed alkaline-earth effect was considered. The observed relationships between their electrical and structural properties and the mix of alkaline earth cations were different according to the transition metal oxide present.