Bi2O3 B2O3 Glasses Research Articles

Bonding sapphire in air by using Bi2O3–B2O3 glass braze

Sapphire plates were directly bonded with bismuth borate glass braze, 50Bi2O3−50B2O3 (mol%), at 700°C for 20min in air. The microstructure of the sapphire/sapphire joint was studied and the interfacial phases were characterized in detail. The results showed that Al4B2O9 was the main product within the joint domain, the typical microstructure of a joint was the sapphire substrate/glassy phase+Al4B2O9/the sapphire substrate.

Synthesis and characterizations of ultra-low sintering temperature BaTiO3/BaO–ZnO–Bi2O3–B2O3 glass ceramic composite

Novel ultra-low temperature co-fired ceramic composites consisting of BaTiO3 and BaO–ZnO–Bi2O3–B2O3 (BZBB) glass were successfully produced under 500 °C, and their sintering behavior, phase composition, microstructure and dielectric properties as functions of sintering temperature were investigated. The XRD and SEM results showed that there was no reaction between the glass and the ceramic but the Bi24B2O39 was formed in all samples during sintering process. This indicates that the BZBB glass not only acts as sintering aids but also involves in crystal phase formation. The composites with 60–90 wt% of BZBB glass frit could be densified at a sintering temperature of 450 °C for 30 min, and exhibited widely adjustable dielectric constant (35–133) and acceptable dielectric loss (<0.012). In addition, the composites showed good compatibility with Ag electrode, which suggests their suitability for various dielectric applications with ultra-low sintering temperature.

Dy3+ doped LiCl–CaO–Bi2O3–B2O3 glasses for WLED applications

Abstract Dy3+ doped calcium bismuth borate glasses were synthesized in the composition range of xLiCl-(30 − x)CaO-20Bi2O3-50B2O3 + 1 mol% Dy2O3 (x = 0, 2, 5, 7, 10 and 15 mol%, LC0, LC2, LC5, LC7, LC10 and LC15 respectively) using conventional melt-quench technique. Broad XRD profiles confirmed non-crystalline nature of synthesized compositions. The compositional dependencies of structural changes (using FTIR spectra), thermal behavior (using DSC thermographs) and optical band gap (using UV–Vis–NIR spectra) were discussed. Photoluminescence (PL) excitation spectra recorded at 577 nm yielded six different excitation peaks belonging to Dy3+ ions. The PL emission spectra recorded at 451 nm were analyzed to extract different light emission parameters viz. Y/B ratio, color coordinates, correlated color temperature (CCT) following CIE 1931 chromaticity diagram. The emission colors were found to lie in white light region and lies very close to standard white light emission. The CCT of sample LC10 (5335 K) is closest to CCT of standard white light (5615 K) which depicted the optimized concentration of LiCl for application of these glasses in WLED application.

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FT-IR and Raman Studies of LiF doped MgO Bi2O3B2O3 Glass System

A series of fluoride glasses of composition (20-x) MgO xLiF 40Bi2O340B2O3with x=0 to 20 mole%, have been prepared by conventional melt quench method. Optical absorption, XRD, FT-IR and Raman Spectra and DTA measurements were carried out on these glasses. Amorphous nature of these glasses has been confirmed from their XRD profiles. The measured FT-IR and Raman spectra have exhibited the Stretching vibrations of Bi–O bonds in strongly distorted BiO6 octahedral units, B–O–B bonds bending vibrations

Interaction of Nd dopants with broadband emission centers in Bi2O3–B2O3 glass: local energy balance and its influence on optical properties

Chemical and energetic interactions between broadband infrared intrinsic emission centers (IECs) of bismuthates and extrinsic emission centers (EECs) of Nd2O3 dopants were optically and electronically investigated. Although no visible absorption from the IEC was found in untreated Bi2O3–B2O3 glass, it was clearly observed after a moderate thermal treatment of <200 °C, indicating chemical activity of O-deficient sites as the origin of IECs. On the other hand, Nd2O3 doping chemically stabilized the Bi2O3–B2O3 glass and suppressed IEC formation. By using a microwave measurement sensitive to electric dipoles, we found a ‘switching’ in local energy balance resulting from the Nd2O3 doping. This was explained by metallization of the O-deficient sites in the Bi2O3–B2O3 glass and multi-phonon excitation of IEC and EEC complexes in the Nd2O3–Bi2O3–B2O3 glass phosphor. Although the electric dipole observed by the microwave measurement was not necessarily caused by IEC, emission properties of the IEC and EEC complexes were consistent with energy balance switching; emissions from IECs after thermal treatment were quenched by EECs with multi-phonon excitation.

Formation of Bi2ZnB2O7 Nanocrystals in ZnO–Bi2O3–B2O3 Glass Induced by Femtosecond Laser

We report on the formation of Bi2ZnB2O7 crystal structures with designated patterns in ZnO–Bi2O3–B2O3 glass by femtosecond laser direct writing. The crystallization mechanism in glass is investigated by crystallization kinetics analysis and simulation of the three‐dimensional temperature field distribution. The crystallized regions show larger third‐order optical nonlinearity than the unirradiated region in glass by Z‐scan technique. This finding is of great potential in application of nonlinear optical integrated devices and development of new nonlinear materials.

Structural, optical and magnetic properties of Fe3O4 sputtered TeO2–PbO–B2O3 and PbO–Bi2O3–B2O3 glasses for sensing applications

The Fe3O4 nanoparticles, incorporated into two diamagnetic glasses (TeO2–PbO–B2O3 and PbO–Bi2O3–B2O3) by DC magnetron sputtering, were annealed at 300°C for 22h in order to investigate the influence to the thermal stability and magneto-optical properties of glasses. The structure, morphology and magnetic properties of two sputtered glasses were compared and characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and UV–VIS spectra measurements. The Verdet constant of glasses was measured by a home-made optical bench.Sputtered samples (Fe3O4 target) were compared with the one obtained by melt-quenching Fe3O4 nanoparticles. The influence of sputtered Fe3O4 layer thickness on thermal and magneto-optical performance was investigated. The results prove that the magnetic property of both glasses, and especially the TeO2–PbO–B2O3 one, is enhanced after the incorporation of 1–5μm-thick-Fe3O4 layer deposited by sputtering. Compared with the uncoated glasses, no significant degradation in FT-IR transmittance, UV–VIS absorption and thermal stability were discovered. The TeO2–PbO–B2O3–Fe3O4 system exhibits the best thermal and magneto-optical performances for magneto optical applications, within the two glass families.

Insights into the structure of Bi2O3–B2O3 glasses as predicted from density correlations

A model has been presented to correlate both the density and molar volume of Bi2O3–B2O3 glasses with the structure. The model makes use of the available data of the fraction of four coordinated boron to get the concentration of all structural units. The concentration of BO4 units shows a maximum at ~31mol% Bi2O3. There is a nonlinear decrease in the concentration of symmetric BO3 units and an increase in the concentration of BiO6 units. Asymmetric BO3 units start forming for Bi2O3>42mol%. It is deduced that in BiO6 units, oxygen atoms are four coordinated with Bi atoms. The model is able to fit the calculated and experimental density and molar volume and explains the minimum in the molar volume at 22mol% Bi2O3.

Large third-order optical nonlinearity of ZnO–Bi2O3–B2O3 glass–ceramic containing Bi2ZnB2O7 nanocrystals

Homogeneous transparent optical glass–ceramics precipitated with unique nonlinear crystals are promising materials for photonic applications. We have utilized heat treatment method to prepare transparent ZnO–Bi 2 O 3 –B 2 O 3 glass–ceramic containing Bi 2 ZnB 2 O 7 nonlinear nanocrystals. A large third-order nonlinear susceptibility χ (3) of glass–ceramic is measured by Z-scan technique, which mainly attributed to unique [BiO 6 ] and [B 2 O 5 ] units in Bi 2 ZnB 2 O 7 crystal structure and the quantum size effect of nanoparticles. The discovery is of great potential in the application of nonlinear optical integrated devices.

Emission analysis of CdO–Bi2O3–B2O3 glasses doped with Eu3+ and Tb3+

This article reports on the emission properties of cadmium bismuth borate (CdBiB) glasses as a function of doping concentrations of Eu3+ and Tb3+ ions. The functional groups present in the glasses have been identified by analyzing FT-IR spectra. The emission spectra of Eu3+ and Tb3+:CdBiB glasses have shown reddish green emissions at 616nm (5D0→7F2) under the excitation at 465nm and at 547nm (5D4→7F5) under the excitation at 485nm, respectively. The Judd–Ofelt (J–O) theory was applied to evaluate the J–O intensity parameters from the absorption and the emission spectra; by using the J–O intensity (Ωλ) parameters, spontaneous emission transition probability (A), total radiative transition rate (AT), radiative lifetime (τR) and branching ratios (β) of the various emission transitions have been computed for both Eu3+ and Tb3+:CdBiB glasses. The quenching behavior in the emission intensity with increased concentration of Eu3+ and Tb3+ was observed, which could be useful for optimizing the compositions toward practical applications.

Fe2O3-Bi2O3-B2O3 glasses as lithium-free nonsilicate pH responsive glasses – Compatibility between pH responsivity and hydrophobicity

Lithium silicate-based glasses have widely been used as commercially available pH glass electrodes. It was revealed that Ti3+-containing titanophosphate (TiO2-P2O5, TP) glasses are pH responsive as lithium-free nonsilicate glasses for the first time. TP glasses with the compatibility between pH responsivity and self-cleaning property were obtained by the sequential post-annealing (oxidation and reduction) of as-prepared glasses. Bi2O3-B2O3 (BiB) glasses are relatively hydrophobic and are expected to show anti-fouling effect. They are unsuitable for pH responsive glasses, because they have high electrical resistivity. In the present study, xFe2O3·yBi2O3·(100−x−y)B2O3 glasses (xFeyBiB, x=0–20mol%, y=20–80mol%) glasses were selected as new pH responsive glasses with hydrophobicity, because Fe2O3 is a representative component for causing hopping conduction to the glasses. BiB glass did not show pH responsivity, whereas xFeyBiB glasses showed good pH responsivity. xFeyBiB glasses are lithium-free nonsilicate pH responsive ones as well as TP glasses. The electrical resistivity and pH response time decreased with increasing Fe2O3 content. The pH repeatability for standard solutions increased with increasing Bi2O3 content. Silicate glass (20Fe70BiSi) showed better pH responsivity but lower contact angle than those of borate glass (20Fe70BiB). pH sensitivity increased in order of TP glasses (about 80%), xFeyBiB glasses (about 90%) and commercial pH responsive glass (about 100%). xFeyBiB glasses showed short pH response time compared to commercial pH responsive glass. The contact angle for water of xFeyBiB glasses was relatively high (about 90°) as well as BiB glasses, and increased slightly with increasing Bi2O3 content regardless Fe2O3 content. The high contact angle was related to low OH content determined by FT-IR measurement. Thus, 20Fe2O3·70Bi2O3·10B2O3 glass was the most suitable one as pH responsive glasses with hydrophobicity. TP glasses are pH responsive ones with self-cleaning property, whereas xFeyBiB glasses are expected as pH responsive ones with anti-fouling property based on hydrophobicity.

Optical basicity and chemical bonding of Bi2O3 containing glasses

Average single bond strength BM–O in kJ/mol of an averaged metal-oxide ion (M–O) chemical bond has been estimated for Bi2O3–P2O5, Bi2O3–B2O3, Bi2O3–SiO2, Bi2O3–GeO2, and CdO–Bi2O3–B2O3 glasses using single bond strength data for simple oxides. It has been found that a decrease in the BM–O is accompanied by an increase in the refractive index based optical basicity Λ(no) of the glasses. The glasses with high Bi2O3 contents of about ~40–70mol% possess smaller values of the average single bond strength in the ~300–160kJ/mol range than the glasses with high B2O3, P2O5, SiO2, and GeO2 contents of about ~80–90mol% (~430–300kJ/mol). It has been assumed that the decrease in the interaction parameter and average single bond strength and the increase in the optical basicity in bismuthate glasses with increasing Bi2O3 content could be connected with the formation of mixed BiOB, BiOP, BiOSi, and BiOGe along with BiOBi bonds which leads to the increased ionicity in comparison with more covalent POP, BOB, SiOSi, and GeOGe bonds. The number of mixed bonds and BiOBi bonds increases and the number of POP, BOB, SiOSi, and GeOGe bonds decreases with increasing Bi2O3 content. An equation for the calculation of optical basicity of SiO2 in Bi2O3–SiO2 glasses has been also suggested taking into account the contribution of different structural units namely SiO40, SiO4−, SiO42−, SiO43−, and SiO44− groups.

Electron paramagnetic resonance, optical absorption and photoluminescence properties of Cu2+ ions in ZnO–Bi2O3–B2O3 glasses

Glass of the composition 23B2O3–5ZnO–72Bi2O3–xCuO (where, x=0.0003, 0.0012 and 0.003at%, in excess) were prepared by a melt-quench technique. The effects of the copper ions on the structural and optical properties of ZnO–Bi2O3–B2O3 glass matrix were analyzed using various spectroscopic techniques. The infrared spectra showed the presence of some bands that are assigned to vibrations of Bi–O bonds from BiO6 octahedral units and B–O bonds from BO3 and BO4 units. The electron paramagnetic resonance spectra revealed the presence of Cu2+ ions in the glass structure in an axially distorted octahedral environment. The number of Cu2+ ions participating in resonance and its paramagnetic susceptibility has been evaluated. The UV–vis spectra show a broad absorption band at 785nm and another band at 438nm which are due to d-d transitions of Cu2+ ions. These glasses are found to exhibit visible and near infrared luminescence bands centered at 548 and 652, and 804nm when excited at 400 and 530nm, respectively. The luminescence centers are supposed to be caused by the lower valence state of bismuth, such as Bi2+ and Bi+ ions, generated during in-situ redox reactions.

Phase, glass formation and the properties of BaO–Bi2O3–B2O3 glasses

Information on phase and glass formation in bismuth-borate systems as a basis for obtaining lead-free low-melting glasses with wide ranging physical and optical properties is generalized. Information on the phase composition and structure in Bi2O3–B2O3 and BaO–Bi2O3–Bi2O3 systems is presented. Data on glass formation and properties in the system BaO–Bi2O3–B2O3 system are presented, including data obtained by the present authors. The rapid development of opto-electronics is making it necessary to search for new optical systems among which bismuth borates occupy a special place, ensuring that glasses based on them are low-melting, comparable to many lead glasses, and giving glass with a considerably higher refractive index together with a much lower heavy-metal oxide content.

Investigation of structural, physical and optical properties of CeO2–Bi2O3–B2O3 glasses

x CeO 2 –30Bi 2 O 3 –(70− x ) B 2 O 3 glasses are synthesized by using the melt quench technique. A number of studies such as XRD, density, molar volume, optical band gap, refractive index and FTIR spectroscopy are employed to characterize the glasses. The band gap decreases from 2.15 to 1.61 eV, refractive index increases from 2.67 to 2.93 and density increases from 4.151 to 4.633 g/cm 3 . The decrease in band gap with CeO 2 doping approaches the semiconductor behavior. FTIR spectroscopy reveals that incorporation of CeO 2 into glass network helps to convert the structural units of [BO 3 ] into [BO 4 ] and results in Bi–O bond vibration of [BiO 6 ].

Electrical transport characteristics of ZnO–Bi2O3–B2O3 glasses

Optically clear glasses in the ZnO–Bi2O3–B2O3 (ZBBO) system were fabricated via the conventional melt-quenching technique. Dielectric constant and loss measurements carried out on ZBBO glasses unraveled nearly frequency (1 kHz–10 MHz)-independent dielectric characteristics associated with significantly low loss (D = 0.004). However, weak temperature response was found with temperature coefficient of dielectric constant 18 ± 4 ppm °C−1 in the 35–250 °C temperature range. The conduction and relaxation phenomena were rationalized using universal AC conductivity power law and modulus formalism respectively. The activation energy for relaxation determined using imaginary parts of modulus peaks was 2.54 eV which was close to that of the DC conduction implying the involvement of similar energy barriers in both the processes. Stretched and power exponents were temperature dependent. The relaxation and conduction in these glasses were attributed to the hoping and migration of Bi3+ cations in their own and different local environment.

Judd–Ofelt theory: optical absorption and NIR emission spectral studies of Nd3+:CdO–Bi2O3–B2O3 glasses for laser applications

This article reports on the optical absorption and NIR emission properties of Nd3+ ions doped CdO–Bi2O3–B2O3 (CdBiB) glasses. Judd–Ofelt theory has been applied to calculate the oscillatory strengths of the transitions in the absorption spectra and also the intensity parameters Ωλ (λ = 2, 4, and 6). These results were then used to compute the radiative properties of emission transitions of Nd3+:CdBiB glasses. From the NIR emission spectra of Nd3+:CdBiB glasses, three NIR emission bands are observed at 900, 1069, and 1338 nm and assigned to the transitions (4F3/2 → 4I9/2), (4F3/2 → 4I11/2), and (4F3/2 → 4I13/2), respectively. The concentration quenching phenomenon has also been explained. The stimulated emission cross-section and FWHM values were calculated for all the Nd3+:CdBiB glasses.

EPR, FTIR, optical absorption and photoluminescence studies of Fe2O3 and CeO2 doped ZnO–Bi2O3–B2O3 glasses

Abstract Glasses containing heavy metal oxide of the composition (wt.%) 23B 2 O 3 –5ZnO–72Bi 2 O 3 – x Fe 2 O 3 /CeO 2 (0 ≤ x ≤ 0.0058 at.% in excess) were prepared by melt quenching technique. The glass formation was confirmed by XRD. FTIR spectra exhibit characteristic absorption bands for B 2 O 3 and Bi 2 O 3 for their various structural units. The EPR spectra exhibit two resonance signals at g ≈ 6.4 and g ≈ 4.2 for Fe 2 O 3 doped glasses. The resonance signals at g ≈ 4.2 and g ≈ 6.4 are attributed to Fe 3+ ions in rhombic and axial symmetry sites, respectively. The number of spins participating in resonance ( N ) and its paramagnetic susceptibility ( χ ) with composition has been evaluated. The effect of CeO 2 and Fe 2 O 3 on optical and structural properties of zinc bismuth borate glass was investigated. From EPR and optical studies it is observed that iron ions are present in trivalent state with distorted octahedral symmetry. The cerium is present in Ce 4+ state. Upon 400 nm excitation the emission at 548 and 652 nm are attributed to the Bi 2+ species. The emission at 804 nm upon 530 nm excitation suggests that Bi + ions are present in the sample. It is interesting to observe that the optical band gap energy ( E opt ) decreases with the increase of transition metal and rare-earth ion doping.

Possible mechanism of charge transport and dielectric relaxation in SrO–Bi2O3–B2O3 glasses

Transparent SrBi2B2O7 glasses were prepared via melt-quenching technique and characterized using differential scanning calorimetry and x-ray powder diffraction. The ac conductivities of the glasses were studied as a function of frequency (100 Hz–10 MHz) at different temperatures. The frequency dependence of conductivity has been analyzed using Almond–West expression. The exponent n was nearly unaffected by temperature. Impedance and modulus spectroscopies were employed to further examine the electrical data. Dielectric relaxation exhibited a stretched exponential behavior with a stretching exponent β independent of temperature. From conductivity analysis we have proposed that the charge transport occurs through the participation of nonbridging oxygen (NBO), which switches positions in a facile manner. The stretched exponential behavior appears to be a direct consequence of the NBO switching mechanism of charge transport.