Structural and thermal stability criteria of Bi 2 O 3 –B 2 O 3 glasses (original) (raw)
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Physical Properties of Bi 2 O 3 -PbO-P 2 O 5 Glasses
Alqalam Journal of Medical and Applied Sciences (AJMAS), 2024
Six glass samples in the system of xBi 2 O 3-(25-x) PbO-75P 2 O 5 (0 ≤ x ≤ 25; x in mol %) were prepared using the conventional melt quenching technique. The physical properties investigated in this research are glass density; ρ, molar volume; V M , oxygen molar volume; V O , oxygen packing density; OPD Poisson's ratio; σ and oxygen ion concentration, N O-ions. The glass density was evaluated experimentally using the Archimedes method and calculated theoretically using an empirical formula. The comparison result for determining density by the two methods was reasonable but not accurate enough. The results showed that density and molar volume increased with increasing Bi 2 O 3 content. For oxygen molar volume (V O) and oxygen packing density (OPD), their behavior was inconsistent, as a slight increase in V O was observed, similarly offset by a decrease in OPD. The Poisson's ratio values indicate the tightening of the bonds in the glass matrix. The number of oxygen ions increases as the bismuth content in the glass increases. Overall, the findings demonstrated that adding bismuth improved the physical properties of the glass samples.
Glass formation and structure of glasses in B2O3―Bi2O3―MoO3 system
Journal of Non-Crystalline Solids, 2011
The purpose of this paper is to study the glass formation tendency in the ternary system B 2 O 3-Bi 2 O 3-MoO 3 and to define the main structural units building the amorphous network. A wide glass formation area was determined which is situated near the Bi 2 O 3-B 2 O 3 side. A liquid phase separation region was observed near the MoO 3-B 2 O 3 side for compositions containing below 25 mol% Bi 2 O 3 and their microheterogeneous structure was observed by SEM. The phase formation was characterized by X-ray diffraction (XRD). By DTA was established the glass transition temperature (T g) in the range of 380-420°C and crystallization temperature (T x) vary between 420 and 540°C. The main building units forming the amorphous network are BO 3 (1270 and 1200 cm − 1), BO 4 (930-880, 1050-1040 cm − 1), MoO 4 (840-760 cm − 1) and BiO 6 (470 cm − 1). It was proved that Bi 2 O 3 favors the BO 3 → BO 4 transformations while MoO 3 preserves BO 3 units in the amorphous network.
2013
By controlled crystallization of glass samples from BaO-B 2 O 3-TiO 2 system glass ceramics can be obtained, based on borates and barium titanate (β-BaB 2 O 4 and BaTiO 3), with potential uses in electronics and electrical engineering. In this paper are presented the obtaining and some properties of glasses from the ternary system BaO-B 2 O 3-TiO 2 , containing B 2 O 3 between 20 and 50 molar%. For the obtained samples were determined density, thermal expansion coefficient, micro hardness, viscosity and hydrolytic stability. Determinations were also made by differential thermal analysis (DTA). The variation of the determined properties according to the oxide glass composition was explained. Prin cristalizarea controlată a probelor de sticlă din sistemul BaO-B 2 O 3-TiO 2 se pot obţine vitroceramici pe bază de boraţi şi titanaţi de bariu (β-BaB 2 O 4 şi BaTiO 3), cu potenţiale utilizări în electronică şi electrotehnică. În această lucrare sunt prezentate modul de obţinere precum şi o...
Role of Bi2O3 content on physical, optical and vibrational studies in Bi2O3–ZnO–B2O3 glasses
Journal of Alloys and Compounds, 2008
Glasses with composition (85−x)Bi2O3–xZnO–15B2O3 with 15 ≤ x ≤ 40 have been prepared by conventional melt quench technique. Systematic variation in density and molar volume in these glasses indicates the effect of Bi2O3 on the glass structure. The parameters glass transition temperature (Tg), change in the transition temperature (ΔTg) and specific heat capacity difference (ΔCp) in the glass transition range were measured. The values of optical band gap and theoretical optical basicity are also reported. Raman and infrared studies have been employed on these glasses in order to obtain information regarding the competitive role of Bi2O3 in the formation of glass network.
Structure and nonisothermal crystallisation of glasses in the BaO–B2O3–TiO2 system
The structure and devitrification behaviour of barium borotitanate glasses, examined by Fourier transform infrared spectroscopy, differential thermal analysis and x-ray diffraction, are reported. Glass compositions are expressed by the formula: (50-x/2)BaO.(50-x/2)B 2 O 3 .xTiO 2 with x=4, 8 and 16. Titanium acting as glassformer gives a more polymerised structure increasing the glass stability with respect to devitrification. The nonisothermal devitrification of the studied glasses occurs in one or two steps depending on the TiO 2 content in the glass composition and the specific surface area of the sample. The surface crystallisation was found to be dominant for all glasses. The investigated glasses devitrify forming b-BaB 2 O 4 microcrystals as the main crystalline phase.
2011
Synthesis of a new series of lead free low softening point (<470 o C) high Bi 2 O 3 (40-90 mol %) glasses in the K 2 O-B 2 O 3-Bi 2 O 3 system by the melt-quench technique has been demonstrated here. Their structural, optical, thermal, electrical and other physical properties have been evaluated by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Fourier transformation infrared reflection spectroscopy (FTIRR), UV-Visible spectroscopy, dilatometer, LCR meter, etc. techniques. The glass softening point, glass transition temperature and glass deformation temperature are found to vary in the ranges 410-465 o C, 354-409 o C and 376-427 o C respectively which are found to correlate well with the boron anomaly phenomenon (as revealed by FT-infrared reflection spectroscopy) with gradual addition of Bi 2 O 3 in the glass matrix. The coefficient of thermal expansion shows a decreasing trend from 153 down to 109 x 10-7 K-1 whereas the dielectric constant increases from 21 to 34 with the increase in Bi 2 O 3 content. The theoretical optical basicity is found to increase from 0.93 to 1.15 while the optical band gap decreases from 2.86 down to 2.30 eV with the addition of Bi 2 O 3. The formation of metallic bismuth in these glasses during melting in air has been confirmed by the X-ray diffraction, transmission electron microscopy, selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM) analyses. The formation of Bi 2 O 3 rich secondary phase in the glasses and their particle size distribution has been examined by the field emission scanning electron microscopy photomicrograph analysis.
Thermal behavior and the properties of BaO–B2O3–P2O5 glasses
Journal of Thermal Analysis and Calorimetry, 2016
Borophosphate glasses of the BaO-B 2 O 3-P 2 O 5 ternary system were prepared and studied within the large glass-forming region of the system. Fourteen investigated glass samples of barium borophosphate glasses were discussed for a comparison of the compositional trends in their properties in four compositional series such as A: (100x)Ba(PO 3) 2-xB 2 O 3 , B: 40BaO-yB 2 O 3-(60y) P 2 O 5 , C: (50z)BaO-zB 2 O 3-50P 2 O 5 , and D: (60w)BaO-wB 2 O 3-40P 2 O 5. Changes in glass density and molar volume primarily depend on the BaO content in the glasses. The thermal properties were studied with a differential thermal analysis, hot-stage microscopy, and dilatometry. Glass transition temperature increases with a rising B 2 O 3 content most rapidly in the glass series A and B. It reaches its maximum in these series for the glasses containing 20-30 mol%, where the glass network represents a 3D structure interlinked with P-O-B, P-O-P, and B-O-B bridges. The thermal expansion coefficient decreases, in contrast, with the increasing B 2 O 3 content in these ternary glasses as well as their chemical durability. The crystallization of these glasses, in the samples with a low B 2 O 3 content, results in the formation of barium metaphosphate BaP 2 O 6. Certain crystallized samples also contain a small amount of BPO 4 , and diffraction lines of ternary compounds BaBPO 5 and Ba 3 B(PO 4) 3 were revealed in a number of samples. A new compound of the composition Ba 5 B 2 P 8 O 28 was identified in the crystallized glass 50BaO-10B 2 O 3-40P 2 O 5 .
Structure and crystallization behavior of glasses in the BaO–B2O3–Al2O3 system
Journal of Non-Crystalline Solids, 1999
The structure and the devitri®cation behavior of barium aluminoborate glasses, examined by Fourier transform infrared spectroscopy, dierential thermal analysis and X-ray diraction are reported. The glass compositions are expressed by the general formula: (50 À x/2)BaOá(50 À x/2)B 2 O 3 áxAl 2 O 3 with x 2, 4 and 8. All the as-quenched glasses were phase separated. Aluminum acting as glass former gives a more polymerized structure increasing the glass stability with respect to the devitri®cation process. Surface crystallization was found to be dominant for all glasses, forming bBaB 2 O 4 nanocrystals as the main crystalline phase. Ó 0022-3093/99/$ -see front matter Ó 1999 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 -3 0 9 3 ( 9 9 ) 0 0 5 5 4 -2