Bismuth-based Glass Research Articles

Analysis of microstructural and interface boding mechanism of jointed ZrO2 / TC4 alloy using bismuth-based glass brazing filler

ZrO2 ceramic and Ti-6Al-4 V (TC4 alloy) was connected by air reaction welding with 35Bi2O3-50B2O3-15ZnO glass. Firstly, the bismuth-based glass powder with low glass transition temperature was synthesized by melt quenching method, and then mixed with organic solvent to prepare glass solder paste. The glass solder paste was printed on the surface of ZrO2 ceramic and TC4 alloy and brazing at the temperature of 420 °C-520 °C for 20 min. The effect of brazing temperature on the shear strength of ZrO2/TC4 joints were tested, and the bonding mechanism of the joint interface was investigated. The results indicated that the shear strength of ZrO2/TC4 joint was affected by glass crystallization, and increased firstly and then decreased with the increase of brazing temperature. The maximum shear strength of the joint reached 48.75 MPa at 500 °C for 20 min. The Ti element in the oxide layer of TC4 alloy diffused into the glass filler and reacted with the components in the glass to form Bi4Ti3O12, which enhanced the interface binding force between the glass filler and TC4 alloy. However, there was no obvious element diffusion between ZrO2 ceramic and glass filler, which was the weak interface in ZrO2/TC4 joints.

Sol–gel synthesis and characterization of silica intertwined bismuth-based bioactive glass coalescence possibility towards biological applications

Sol–gel synthesis and characterization of silica intertwined bismuth-based bioactive glass coalescence possibility towards biological applications

Microstructure evolution and properties of dissimilar YIG/MTC joint fabricated with bismuth-based glass ceramic

The paper uncovers microstructural evolution and bonding mechanism of yttrium iron garnet ferrite (YIG) and magnesium titanate ceramic (MTC) brazed by bismuth-based glass ceramic. The resulting mechanical and dielectric properties of the proposed YIG/MTC joint were investigated in detail. The reaction mechanism was thoroughly studied. Micro and nano CoFe2O4 were generated in the glass seam. Besides, a CoFe2O4 reaction layer was formed at the interface of MTC/glass ceramic. The atoms stacked along the plane (220), and a complete coherent boundary was emerged between the CoFe2O4 reaction layer and MTC ceramic subsequently. YBO3 clusters were formed at YIG/glass interface and Bi9Ti3Fe5O27 stripe phases were generated in the glass matrix. The joint shear strength increased with the brazing temperature increasing, and reached a maximum value of 72 MPa at 800 °C. The dielectric constant of YIG/MTC joint varied from 16.5 to 17.9, and the dielectric loss tangent was nearly 0.001 at higher frequency.

Optical, emission, and excitation dynamics of Eu3+ -doped bismuth-based phosphate glass for visible display laser applications.

Eu3+ -doped-bismuth-based phosphate glasses with chemical equation (60 - x)P2 O5 -20Bi2 O3 -10Na2 CO3 -10SrF2 -xEu2 O3 (PBNSEu), (where x= 0, 0.1, 0.5, 1.0, 1.5 and 2mol%) were fabricated using the melt-quenching method. Obtain X-ray diffraction (XRD), energy-dispersive X-ray (EDAX), and Fourier transform infrared (FTIR) spectra were used to characterize the structure of the prepared PBNSEu glass. The J-O (Judd-Ofelt) intensity parameters (Ω2 , Ω4 ) were estimated using photoluminescence emission spectra. When excited with a xenon lamp at λexc = 394 nm, the most intense red-emission transition occurred at ~612 nm (5 D0 →7 F2 ). J-O intensity parameters were used to calculate radiative properties, whereas the radiative branching ratio (βR ), radiative transition probability (AR ), radiative lifetime (τR ), and total radiative transition rate (Aτ ) were calculated for the transitions 5 D0 →7 FJ (where J = 0-4) and were obtained in the emission spectra for europium ion-doped in the current glass. Using the CIE1931 chromaticity coordinates axes, the colours of various concentrations of Eu3+ ion-doped PBNS glass were evaluated using the emission spectra. Temperature-dependent luminescence spectra were recorded for the optimized PBNSEu20 glass to calculate the activation energy. These results strongly suggested red components in w-LEDs and visible display laser applications.

Crystalline-liquid duality of specific heat in halide perovskite semiconductor

Crystalline-liquid duality in specific heat is observed in lead-free bismuth halide perovskite A3Bi2×9 [A= FA, MA, Cs, and X = I, Br, Cl] semiconductor. All crystals exhibit unusual liquid-like behavior and show substantial deviation from the classical Dulong-Petit law at room temperature. This unusual liquid-like behavior of specific heat is attributed to the dynamic disorder and strong anharmonicity in the soft crystal lattice. The low-temperature specific heat was modeled using the combined Debye-Einstein model and obtained Einstein modes demonstrate strong anharmonic coupling of the low-energy optical modes with acoustic modes resulting in ultrasoft frequency dampening of acoustic phonons. The combination of strong acoustic−optical phonon coupling, soft elastic layered structure, and abundance of low-energy optical phonons results in anomalous thermodynamic specific heat duality in these bismuth-based phonon glass electron crystals. Our study is of fundamental interest in thermodynamics and will help to design novel thermoelectric materials.

Fracture Surface Analysis, Physical, Optical and Dielectric Properties of Bismuth-Based Glass Doped with Potassium Chromate

Bismuth glasses have been prepared from a commercial-grade chemical glass mixture doped with potassium chromate in different contents. They have been melted at 1250 °C for 4 h, quenched in a metal plate, and annealed at 500 °C for 20 min. The surface morphology of glass samples has been examined using scanning electron microscopy (SEM). The dielectric properties have been investigated. UV-Vis-NIR absorption has been analyzed. The results show the growth of microcrystal precipitated in the glass matrix, and colors of glass change from colorless to green and opaque with the increasing content of potassium chromate. The density of glass decreases with the increasing content of potassium chromate. The UV-Vis spectra show strong absorption of UV. The chromium-doped glasses not only absorb the UV but also the violet and/or blue lights which depend on the chromium contents.

Optical and radiation shielding properties of Sm3+ ions embedded bismuth-based fluorophosphate glasses for γ-ray shielding and multi-band visible laser applications

Bismuth based fluorophosphate (PBNS) glasses doped with samarium ions were fabricated by well-known melt quenching method. The structural, optical and fluorescence properties of PBNS glasses, were extensively investigated via XRD, FTIR, EDAX, optical absorption and fluorescence emission along with lifetime decay analysis. The intensity parameters (Ω2, Ω4, Ω6) were calculated using the Judd – Ofelt hypothesis, which follows the Ω4 > Ω6 >Ω2 trend. PBNSSm glasses doped with 1.0 mol% samarium ions (PBNSSm10) had a greater emission peak intensity than the produced glasses according to the emission spectra. The 4G5/2 → 6H7/2 transition emitting the radiation at 597 nm was more intense than the other transitions and got higher values for optical gain bandwidth (10.70 x 10−25 cm3), stimulated emission cross-section (10.05 x 10−20 cm2) branching ratio (0.48), and optical gain parameter (28.65 x 10−25 cm2s). The emission spectral results have been used to evaluate the colorimetric analysis of the 1931 CIE coordinates, and CCT values fall in the visible spectrum region. Moreover, the degree of protection of the synthesized PBNS glasses against gamma radiation was also evaluated. The obtained results suggested that the PBNS glass doped with 1.0 Sm3+ ions could be useful for multi-band visible laser applications. It was also concluded that 2.0% Sm3+ addition effectively increases the gamma-ray shielding properties of PBNS glasses, and therefore PBNSSm20 can be an alternative shielding material.

A novel route to synthesize BiOCl1-xBrx solid solution with excellent photocatalytic performance in visible range by etching bismuth glass

In this paper, as solar energy materials BiOCl1-xBrx (0 ≤ x ≤ 1) semiconductors with ultra-high photocatalytic performance were prepared by etching bismuth-based glass. The unique formation mechanism of BiOCl1-xBrx powders was put forward and the phase composition, microstructure, energy band and photocatalytic performance of the BiOCl1-xBrx nanocomposites were characterized. The results show that continuous solid solution BiOCl1-xBrx powders with nanosheet morphology were synthesized. Meanwhile, the energy band of the BiOCl1-xBrx powders could be controlled by the replacement of Cl with Br. Among all the BiOCl1-xBrx powders, BiOCl0.6Br0.4 possessed optimal photocatalytic performance in visible range by evaluating the photodegradation of rhodamine (93.6%/40 min). This new strategy can be adopt to design effective photocatalysts for solar energy utilization and environmental purification.

Influence of optimized concentration of Dy3+ ions on optical and luminescence properties of P2O5 + Bi2O3 + Na2CO3 + SrF2 glasses for solid state visible laser and w-LED applications

The fluoride-based bismuth phosphate (PBNS) glasses are doped with Dysprosium ions are fabricated by using the method conventional melt quenching. For synthesized PBNS glasses physical parameters were evaluating, moreover, the structural, optical, and fluorescence properties were analyzed/studied by XRD, FTIR, EDAX, photoluminescence study analysis, and optical absorption. The optical band gap is estimated based on the tauc's curve extracted from the absorption spectrum, and the value obtained shows a non-linear behavior with the concentration of doping ions. The intensity parameters (Ω 2 , Ω 4, Ω 6 .) were evaluated using Judd – Ofelt theory and which follows Ω 2 > Ω 4 > Ω 6 trend. From the emission spectra, the PBNSDy glasses doped with 1.0 mol% Dysprosium ions (PBNSDy10) attains the higher emission peak intensity among the prepared glasses. The 6 H 15/2 → 6 F 11/2 transition emitting the radiation at 473 nm was more intense than the other transition and attains a higher value for optical gain bandwidth (28.66 × 10 −25 cm 2 S), Stimulated emission cross-section (5.45 × 10 −21 cm 2 ) and branching ratio (0.63). The emission spectra are used to evaluate by colorimetric analysis of the 1931 CIE color coordinates, Y/B intensity ratio, and CCT values to see the adaptability of the fluorophosphate glass to solid-state white light LED applications. • Dy 3+ ions doped bismuth-based fluorophosphate glasses were prepared. • JO spectral intensity parameters were evaluated. • The 6 H 15/2 → 6 F 11/2 transition has higher σ emi (5.45 × 10 −21 cm 2 ) and β (0.63) values • CIE color coordinates were evaluated. • PBNSDy10 glass could be used for design of visible lasers/w-LEDs.

Microstructure and performance characterization of in-situ Co2FeO4 whiskers reinforced YIG/YIG joints

Bismuth-based glasses doped with different CoO contents were designed to realize the in-situ growth of Co2FeO4 whiskers in YIG/YIG joint. The microstructure, mechanical and dielectric properties of the joints were systematically investigated. The optimized processing joint with 23 mol% CoO doping, brazed at 725 °C for 15 min, under bonding pressure of 6 kPa was achieved. And the shear strength of joint reached a maximum of 72 MPa, which is attributed to the increased number and optimized spatial distribution of Co2FeO4 whiskers. The in-situ Co2FeO4 whiskers acted as effective hard phases in the glass matrix. The shear strength of YIG/YIG joint was enhanced by the crack propagation deflection and pulling out result from Co2FeO4 whiskers. The dielectric constant of YIG joints decreased from 16.2 to 15.3 at the frequency of 10 MHz, which is closer to that of the original YIG material with the CoO doping increasing. The dielectric loss tangent increased slightly with the growth of Co2FeO4 whiskers due to the hole hopping between Co3+⇔Co2+ ions. The effective bonding of YIG materials has broad application prospects for the integration of ferrite microwave devices.

Radiation shielding and mechanical properties of Bi2O3–Na2O–TiO2–ZnO–TeO2 glass system

Recently, heavy metal oxides (HMO) based glass systems attracted great attention to the scientific community to be used as an alternative to the conventional lead, lead composites and concrete based materials for protection of harmful radiation. In this work, we report the role of Bi2O3 on the mechanical and radiation shielding properties of Bi2O3–ZnO–TiO2–Na2O–TeO2 glass system as well as its mechanical behaviour. The mechanical properties of the glasses were calculated using Makishima-Mackenzie model and different shielding factors have been calculated using Monte Carlo simulation via Geant4 code and also using Phy-X software. The mechanical properties based on Makishima-Mackenzie model depend on the values of packing density (Vi) and dissociation energy (Gi) of the oxide constituents. The simulated values of the mass attenuation coefficient showed a good agreement between both approaches. The mass attenuation coefficient (MAC) at 0.284 MeV of the glass with 5 mol% of Bi2O3 is equal to 0.2083 cm2/g, at 0.662 MeV its equal to 0.0785 cm2/g, while at 1.33 MeV, its MAC is 0.0501 cm2/g. The transmitted percentage of the photons through the proposed glasses was found to rise with increasing the energy of the photon, while decreasing with rising the thickness of the glass sample. The transmission factor (TF) revealed that the greater the thickness of the glass, the lower the TF, and the better the shield. Also, the radiation protection efficiency of the glasses was enhanced with the addition of the Bi2O3. The glass sample with composition of 15Bi2O3–10ZnO–5TiO2–5Na2O–65TeO2 possesses the highest effective atomic number among the studied compositions and showed the lowest half value layer. From the obtained data, Bi2O3 seems to be a strong candidate for enhancing the gamma radiation attenuation factors in the bismuth-based tellurite glasses.

Thermal, structural and optical properties of Bi2O3-Na2O-TiO2-ZnO-TeO2 glass system

Tellurite glasses have found wide applications in laser, nonlinear optics and optical communication. This paper describes the role of Bi2O3 on the physical and optical properties of glasses with molar composition of xBi2O3-5Na2O-5TiO2-10ZnO-(80-x)TeO2, where x = 5, 8, 10, 12, and 15 mol.% synthesized using conventional melt quenching technique. The thermal properties of the sample glasses, such as glass transition temperature (Tg), onset crystallization temperature (Tx), and glass stability (S), were estimated from the differential scanning calorimetry measurements. The glass stability was found to decrease as Bi2O3 content increased. The decrement was due to: (i) the decomposition of strong TeO4 units into TeO3+1 polyhedra and TeO3 units; (ii) the replacement of strong Te‒O‒Te bonds by weaker Te‒O‒Bi bonds; and (iii) the formation of weak Bi‒O‒Bi bonds that were shown in Raman and FTIR results contributed to the weakening of the glass stability. The measurements from the UV-Vis spectrophotometer indicated a drop in the optical band gap with increasing Bi2O3 content. A low energy band gap is evidence of glasses with high polarizability which could be due to thehigh polarizability of non-bridging oxygen. This finding, among others in this study, shows that the synthesized bismuth-based tellurite glass is suitable as a potential optical material in the optical and photonic applications.

Prediction of mechanical and radiation parameters of glasses with high Bi2O3 concentration

This study aims to perform multidirectional characterizations on nuclear shielding efficiencies on some bismuth-based glasses. Accordingly, the γattenuation coefficients for xBi2O3-(75-x)B2O3–25Li2O (x = 0, 10, 20, 30, 40, 50, 60 the 70 mol%) were widely evaluated using simulations and theoretical methods. Linear attenuation coefficient (LAC) of the glasses was obtained by the Monte Carlo general-purpose simulation code FLUKA and compared with the XCOM database up to 15 MeV. Moreover, LAC values have been utilized to evaluate related parameters like mass attenuation coefficient (MAC), total molecular cross-section (σt), total atomic cross-section (σa), half-value layer (HVL), total electronic cross-section (σe), mean free path (MFP), effective atomic number (Zeff), and effective electron density (Neff). The results noted that the XCOM and FLUKA data of the shielding parameters are in great agreement. Relatively higher density (5.818 g/cm3), greater LAC, MAC, Zeff, and lower HVL, MFP values are achieved for 70Bi2O3-5B2O3–25Li2O glass. Accordingly, this glass sample is a better gamma shield.

The influence of Bi2O3 glass powder in the silver paste and the impact on silicon solar cell substrates

The present work critically investigates the fabrication of metal contacts to advanced applications of bismuth-based oxide glass and screen-printed silver contacts for use in integrated circuits (I.C.s), solar cells, and sensors. Electrode contacts were fabricated by screen printing composite pastes composed of mainly silver powder, Bi2O3 glass powder, and acyclic binder, and then firing the pastes in a belt furnace. The composite films' microstructures after firing at 830–890 °C were observed under various corrosion conditions, and the resulting layers were analyzed with X-ray diffraction (XRD) and the transfer length method (TLM). A series of investigations to determine the influence of Bi2O3 glass in silver paste involved differential thermal analysis (DTA), scanning electron microscopy (SEM), electron probe X-ray microanalysis (EPMA), secondary ion mass spectrometry (SIMS), and transmission electron microscopy (TEM), to determine the effects of Bi2O3 mixed with silver and the efficacy of the resulting metal contacts in I.C. fabrications. Results show that increasing firing temperature and the additive of Bi2O3 glass controlled the silver's melting into the glass and influenced Ag crystallites' precipitation.

Effect of BaO on the structure and properties of bismuth-based low-melting glasses

ABSTRACT The effect of BaO on the structure and properties of bismuth-based low-melting sealing glasses (Bi2O3–B2O3–ZnO–SiO2–Al2O3–BaO) were investigated by FTIR, 27Al NMR and DSC. The results showed that when BaO content was less than or equal to 3 wt-%, BaO provided (O2–) free oxide ions, which made [AlO6] transform into [AlO4] and made [BO3] transform into [BO4]. The increase of [AlO4] and [BO4] enhanced the network structure and decreased the thermal expansion coefficient of glass-ceramic. But when BaO was more than 3 wt-%, a large amount of Ba2+ , considered as an external body of network, entered the gap of glass network and weakened the existing bridge oxygen vibration in the glass structure and increased the thermal expansion coefficient. Besides, the crystallisation ability of glasses would be promoted by increasing the heat treatment temperature or the BaO content. The formation of BaAl2Si2O8 crystal would improve the acidity resistance of the glass-ceramic to a certain extent.

Microstructure and properties of YIG/bismuth-based composite glass/YIG joints with growth of in situ MgFe2O4 whiskers

Bismuth-based glasses doped with MgO nanoparticles were designed to realize the in situ growth of MgFe2O4 whiskers with the aim of improving the mechanical and magnetic properties of YIG/YIG joints. The microstructure of the joints and the formation mechanism of MgFe2O4 whiskers were systematically investigated, as well as the mechanical and magnetic properties. The MgFe2O4 nuclei grew along the [001] orientation to form MgFe2O4 whiskers. The shear strength of YIG/YIG joints increased with an increase in doping of MgO nanoparticles, reaching a maximum of 67.5 MPa for the joint brazed with Bi25-21MgO. It indicated that MgFe2O4 whiskers play an important role in strengthening the joints. The magnetic force microscopy (MFM) and vibrating sample magnetometer (VSM) results indicated that the magnetic properties of the brazing seam improved with the growth of in situ magnetic MgFe2O4 whiskers. The magnetism of YIG/YIG joints could be intensified by brazing with Bi25-21MgO composite glass.

A new design of the YIG/MTC joint brazed by bismuth-based glass

The paper uncovers an underlined mechanism of joining Yttrium Iron Garnet (YIG) and Magnesium Titanate Ceramic (MTC) with a bismuth-based glass braze. The proposed joint design has not been investigated until present. The central hypothesis is as follows. The brazed bismuth-based glass microstructure and the resulting mechanical strength of a YIG/MTC joint design support favorably a good bonding of the interface domains. The supporting evidence includes the following: (i) the bismuth-based glass features good wettability on YIG and MTC, (ii) the sequence of the coefficients of thermal expansions (YIG, bismuth-based glass, MTC) is in a favorable succession. The study reveals that the interface reactions form: (i) a lamellar phase and YBO3 whiskers at the YIG/Bi25 interface, (ii) both MgFe2O4, and Bi4Ti3O12 whiskers in addition to Zn2Ti3O8 reaction layer at the MTC/Bi25 interface, and (iii) Fe2O3 phase along the brazing seam. The mechanical integrity of joints has been studied as well.

Wetting behavior and bonding characteristics of bismuth-based glass brazes used to join Li-Ti ferrite systems

Abstract A series of bismuth-based glass brazes were used to join Li-Ti ferrite. The wetting behavior and bonding characteristics of glass brazes utilized to join Li-Ti ferrite were systematically investigated. The glass brazes feature a good CTEs match, and a favorable wetting ability over Li-Ti ferrite mating surfaces. Upon brazing, the Bi-rich phases (Bi 46 Fe 2 O 72 , Bi 12 SiO 2 and Bi 24 B 2 O 39 ) and Zn-rich phase (ZnO) were observed in the Li-Ti ferrite/Bi40 and Li-Ti ferrite/Bi35 joints. The Zn 2 SiO 4 , ZnFe 2 O 4 and Bi 5 Ti 3 FeO 15 whiskers were detected in the Li-Ti ferrite/Bi25, Li-Ti ferrite/Bi20 and Li-Ti ferrite/Bi25-BC joints, respectively. No crystalline phase was detected in the Li-Ti ferrite/Bi30-BF joint. Multiple factors impact the joint strength, such as the three-point bending strength of glass brazes, the CTE match of the glass braze and the Li-Ti ferrite, as well as the crystal phases within the seam. The joint strength has the maximum value of 86 MPa for a Li-Ti ferrite/Bi25-Ba couples. The main impact is attributed to the strengthening effect of Bi 5 Ti 3 FeO 15 whiskers. The dielectric properties of Li-Ti ferrite/glass braze joints show a stronger frequency dependence than that of Li-Ti ferrite at low frequency. This is attributed to the formation of new interfaces. The glass matrix or a crystal phase with a higher dielectric constant could counteract the decrease in the dielectric constant of heat-treated Li-Ti ferrite. Therefore, the dielectric constant of joint, especially that of Li-Ti ferrite/Bi25-BC joint, would be near that of the original Li-Ti ferrite at a high frequency. Meanwhile, no increase in the dielectric loss tangent of a joint takes place.

Bismuth silicate glass containing heavy metal oxide as a promising radiation shielding material

ABSTRACTOptical and FTIR spectroscopic measurements and electron paramagnetic resonance (EPR) properties have been utilized to investigate and characterize the given compositions of binary bismuth silicate glasses. In this work, it is aimed to study the possibility of using the prepared bismuth silicate glasses as a good shielding material for γ-rays in which adding bismuth oxide to silicate glasses causes distinguish increase in its density by an order of magnitude ranging from one to two more than mono divalent oxides. The good thermal stability and high density of the bismuth-based silicate glass encourage many studies to be undertaken to understand its radiation shielding efficiency. For this purpose a glass containing 20% bismuth oxide and 80% SiO2 was prepared using the melting–annealing technique. In addition the effects of adding some alkali heavy metal oxides to this glass, such as PbO, BaO or SrO, were also studied. EPR measurements show that the prepared glasses have good stability when exposed to γ-irradiation. The changes in the FTIR spectra due to the presence of metal oxides were referred to the different housing positions and physical properties of the respective divalent Sr2+, Ba2+ and Pb2+ ions. Calculations of optical band gap energies were presented for some selected glasses from the UV data to support the probability of using these glasses as a gamma radiation shielding material. The results showed stability of both optical and magnetic spectra of the studied glasses toward gamma irradiation, which validates their irradiation shielding behavior and suitability as the radiation shielding candidate materials.

Optical Analysis of Bismuth-Based Glasses Doped Potassium Chromate

In this study, Bismuth-based glasses were prepared and doped with various concentration of potassium chromate. They were melted in an electrical furnace at 1250°C for 4 hours then pressed with fire frame to plate shape and annealed at 500°C for 10 min. Optical spectra were used to analyze color shade of glasses. Homogeneity of glasses was analyzed by birefringence technique. Glasses color was changed from colorless to slightly and opaque green with an increasing amount of potassium dichromate and birefringence result showed that the glasses are non-homogenous.