Influence of SiO2 substitution for B2O3 on the properties of borosilicate glasses I. Kashif,*,1 E. M. Sakr, A. A. Soliman & A. Ratep (original) (raw)
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Asian Journal of Convergence in Technology
Glass sample compositions of xCaO(1-x-z)-SiO 2 zB 2 O 3 with constant nominal CaO of x=33.33 mol% and varying concentrations of B 2 O 3 as z=50,60 and 66.67 mol% are prepared by conventional melt quench technique. Fourier transform infrared (FTIR) spectra of xCaO(1-x-z)-SiO 2 zB 2 O 3 glass system has been measured in the spectral range 400-4000 cm −1 low-frequency region 1700cm-1 to 400cm-1 and highfrequency region 4000cm-1 to 1700cm-1) at room temperature to understand the characteristic frequencies of the chemical bonds, bonding mechanisms and structure of electron shell of atoms, for the purpose to determine the molecular structure of the composition. It is found that the melting temperature of the glasses decreases with the increase of B 2 O 3 concentration and the melting temperature in the range of 950 o C-1100 o C for the samples which consist of 50, 60, and 66.67 mol% of B 2 O 3. In the low-frequency region (1700cm-1 to 400cm-1) the spectra of high B 2 O 3 containing glass showed an increased number of distinct peaks and several broad Gaussian in the thighfrequency region (1700cm-1 to 400cm-1). All the spectra are based on line corrected and deconvoluted to the appropriate number of Gaussians. Fourier transform infrared (FTIR) deconvoluted spectra were analyzed to determine the exact position and relative amounts of the IR bands responsible for the different silicate borates units. The distinct peaks and peak position of the deconvoluted Gaussians are assigned to Si-O-Si, B-O-B, Si-O-Ca, Si-O etc. bonds based on the previous scientific investigations. The presence of B 2 O 3 in the materials suggests that B 3+ occupies the network position and for the linkage Si-O-B in the glasses. The amorphous nature, the surface topography and composition of the prepared glasses was checked by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques respectively on optical inspection, did not show any evidence of phase separation, and all glasses are homogeneous.
Influence of Al2O3 Addition on Structure and Mechanical Properties of Borosilicate Glasses
Frontiers in Materials, 2020
Alkali-borosilicate glasses are one of the most used types of glasses with a high technological importance. In order to optimize glasses for diverse applications, an understanding of the correlation between microscopic structure and macroscopic properties is of central interest in materials science. It has been found that the crack initiation in borosilicate glasses can be influenced by changes in network interconnectivity. In the NBS2 borosilicate glass system (74.0SiO 2-20.7B 2 O 3-4.3Na 2 O-1.0Al 2 O 3 in mol%) two subnetworks are present, i.e., a silicate and a borate network. Increasing cooling rates during processing were found to improve glasses crack resistance. Simultaneously, an increase in the network interconnectivity accompanied by an increasing capacity for densification were noticed. Their individual contribution to the mechanic response, however, remained unclear. In the present study the borosilicate glasses were systematically modified by addition of up to 4.0 mol% Al 2 O 3. Changes in the network connectivity as well as the short-and medium-range order were characterized using Raman and NMR spectroscopy. Both the Raman and the 11 B NMR results show that four-fold-coordinated boron is converted into threefold coordination as the Al 2 O 3 content increases. Additionally, 27 Al NMR experiments show that aluminum is dominantly present in four-fold coordination. Aluminum-tetrahedra are thus charge balanced by sodium ions and incorporated into the silicate network. Finally, nanoindentation testing was employed to link the inherent glass structure and its network configuration to the mechanical glass response. It was found that the glass softens with increasing Al 2 O 3 content, which enhances the crack resistance of the borosilicate glass.
Structural studies on boroaluminosilicate glasses
Journal of Non-Crystalline Solids, 2008
Two series of boroaluminosilicate glasses having varying mole ratios of B 2 O 3 /Na 2 O (series 1) and B 2 O 3 /SiO 2 (series II) were prepared by conventional melt-quench method. Based on 29 Si and 11 B MAS NMR studies, it has been established that for series I glasses up to 15 mol% B 2 O 3 content, Na 2 O preferentially interacts with B 2 O 3 structural units resulting in the conversion of BO 3 to BO 4 structural units. Above 15 mol% B 2 O 3 for series I glasses and for all the investigated compositions of the series II glasses, silicon structural units are unaffected whereas boron exist in both trigonal and tetrahedral configurations. Variation of microhardness values of these glasses as a function of composition has been explained based on the change in the relative concentration of BO 4 and BO 3 structural units. These glasses in the powder form can act as efficient room temperature ion exchangers for metal ions like Cu 2+ . It is seen that the ion exchange does not affect the boron and silicon structural units as revealed by IR studies. Ó 2007 Published by Elsevier B.V.
Effect of fluoride ion incorporation on the structural aspects of barium–sodium borosilicate glasses
Journal of Non-Crystalline Solids, 2009
Barium-sodium borosilicate glasses containing upto 6 wt% fluoride ions were prepared by conventional melt quench method and characterized by 19 F, 29 Si and 11 B nuclear magnetic resonance (NMR) techniques. 19 F NMR studies have confirmed the presence of mainly linkages like F-Si(n) or F-B(n) along with F-Ba(n). Their relative concentrations are unaffected by F À content in the glass. Incorporation of fluoride ions in the glass is associated with significant reduction in the nonbridging oxygen concentration attached to silicon, as revealed by the increase in the concentration of Q 3 structural units of silicon at the expense of Q 2 structural units. 11 B NMR studies have established that the relative concentrations of BO 3 structural units are higher for F À ion containing glasses compared to the one without F À ion incorporation. The observed increase in the relative concentrations of Q 3 structural units of silicon and BO 3 structural units with fluoride ion incorporation in the glass has been attributed to the formation of F-Ba(n) type of linkages, thereby reducing the concentration of network modifying cations for breaking the Si-O-Si/B-O-B linkages. Formation of such structural units weakens the glass network thereby decreasing the glass transition temperatures.
Role of aluminium oxide in the structure of heavy metal oxide borosilicate glasses
physica status solidi (a), 2012
ABSTRACT Lead borosilicate and bismuth borosilicate glasses with and without aluminium oxide of varying compositions were prepared by conventional melt-quench method. Raman spectroscopy was used to analyze the influence of Al 2O 3 incorporation in the heavy metal oxide borosilicate glass network. The compositions of glasses were chosen in a way that Al 2O 3 is added at expenses of PbO and Bi 2O 3 in lead borosilicate and bismuth borosilicate glasses, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Physica B: Condensed Matter, 2019
BaO-CaO-Al 2 O 3-SiO 2 (BCAS) glass and their derivatives have gained extreme importance for their high endurance to elevated temperatures and suitability for various electrochemical applications. Two glass systems, one being 50mol%[SiO 2-B 2 O 3 ]-xBaO-(45-x)CaO-5Al 2 O 3 with x= 0, 10, 20, 25, 30, 35 and 40 mol%, represented as BCBSA and another without Al 2 O 3 termed as BCBS, synthesized using melt quenching technique are considered here. The authors focus on the thermal and mechanical properties of these glasses. Reducing BaO concentrations improve the coefficient of thermal expansion (CTE/α) and other characteristic temperatures of glasses. Compacted glass pellets made of the water quenched frits show maximum shrinkage at 700 °C. Dilatometric analysis were conducted on compacts showing maximum shrinkage. CTE of these pellets are more than the bulk glasses. Glasses with low BaO concentrations exhibit high hardness and Young's modulus. Glasses bearing 20 mol% BaO, or even lesser, meet the thermal and mechanical properties required for high temperature sealants.
Influence of Bi2O3 on the physical and electrical properties of some Boro-Iron glasses
Journal of Non-Crystalline Solids, 2018
Boro-phosphate oxide glass system doped with iron ions have been prepared by the conventional melting quenching technique, all mixtures are in an agreement with the following chemical formula (25-x) mol% Na 2 O. x mol% NaCl.15 mol% FeO. 30 mol% B 2 O 3. 30 mole% P 2 O 5 , where x = 0.0, 05, 10, 15, 20 and 25. Sample of x= 0, only, has been exposed to different doses of gamma rays (0.0, 05, 10 and 20 kGy). Mossbauer Effect ME spectroscopy have been carried out at RT for all irradiated {x =0.0} and for non-irradiated {x> 0.0} samples. ME parameters showed all samples in good glassy state. Also ME parameters showed the iron ions in two different coordination states, where all Fe 2+ ions and some of Fe 3+ ions shared the octahedral coordination states, while the tetrahedral coordination states occupied only by Fe 3+ ions. It was observed that both the gamma irradiation process and the process of replacement Na 2 O by NaCl caused the Fe 2+ ions to oxidize to Fe 3+ ions.