Increasing BaO Content Research Articles

Enhancing bioactivity, radiopacity, and structural properties of borophosphate glass through barium oxide modification and controlled thermal treatment

This study explores the impact of replacing P2O5 and B2O3 with varying amounts of barium oxide (BaO, 0–10 mol%) in borophosphate glasses. The investigation focuses on the structural, bioactivity, and radiopaque properties of the resulting materials. Four glass samples were prepared using a melt-quench technique. Their bioactivity was assessed through immersion in simulated body fluid (SBF) for 28 days. Additionally, a 24-h thermal treatment at 530 °C was employed to induce crystallization and evaluate the bioactivity of the resulting glass-ceramics. Initial X-ray diffraction (XRD) analysis confirmed the amorphous nature of the glasses. Conversely, crystalline phases were identified after the thermal treatment. Increasing BaO content led to higher volumetric density while altering the molar volume and structure as revealed by Fourier-transform infrared spectroscopy (FTIR) analysis. Lower pH values were observed with increasing BaO content, suggesting its influence on controlling the release of ions from the material. Both XRD and FTIR analyses detected the formation of hydroxyapatite (HAp) and fluorapatite (FAp) phases in all samples. Notably, the glass-ceramic containing 10 mol% BaO exhibited the most significant apatite formation. Radiopacity measurements improved with increasing BaO content, indicating potential applications in bone replacement materials due to enhanced visibility in X-ray imaging. Cell viability tests confirmed the non-toxic nature of the samples, with higher BaO content promoting cell proliferation, suggesting potential for tissue regeneration. Overall, these findings suggest promising biomedical applications for all the studied compositions.

BaO–reinforced SiO2–Na2O–Ca(O/F2)–Al2O3 glasses for radiation safety: On the physical, optical, structural and radiation shielding properties

This paper reports on a study aimed at investigating the physical properties and radiation shielding capability of a low-cost, high-transparency silicate glassy system reinforced with barium oxide. The prepared glasses' elementary and modified network structures were analyzed using X-ray diffraction and Raman spectroscopy, confirming their glass nature and revealing the progressive network depolymerization with BaO inclusion. Differential scanning calorimetry was employed to determine the glass transition temperature, which showed an increase with increasing BaO content. Tauc's plot was used to study the direct optical bandgap, which was observed to increase from 3.91 to 4.75 eV with BaO content from 0 to 30 mol%, linked to an increase in the average oxygen bond chain length and non-bridging oxygen atoms' creation. The density, molar volume, and oxygen packing density of the glass were found to increase with BaO addition, indicating that barium oxide promotes the formation of a compact network structure collapsing into a closely packed arrangement. At an X-ray energy of 40 keV, the mass attenuation coefficient increased from 0.67 to 11.48 cm2/g with BaO content. To assess the efficacy of theoretical calculations, we have conducted an experimental setup to measure the linear attenuation coefficient using an 241Am (59.5 keV) radiation source. Finally, the gamma shielding effectiveness was evaluated, and the sample containing 30 mol% of BaO showed superior radiation protection compared to concrete and was comparable to RS360 commercial glass.

Properties and structure of ternary BaO−SnO−P2O5 glasses

Series of Ba/Sn phosphate glasses (33 and 40 mol% P2O5) are investigated by 31P MAS NMR and neutron diffraction to clarify the effects of substituting Sn with Ba. The structural parameters are related to glass properties, among them to the photoelastic constant (PEC). Different from the increase of the Sn−O coordination number to four in Zn/Sn phosphate glasses (33 mol% P2O5) the NSnOs of 3.2 and 3.4 do not change with substituting Sn with Ba. The stacking of layer-like entities of Sn or Ba oxygen polyhedra is suggested to cause the first scattering peak at 12 nm−1. Non-bridging oxygens shared by two or more Ba2+ lead to stiff networks with increasing BaO content which is accompanied with increasing Tg, decreasing thermal expansion, and better corrosion resistance. The slopes of the compositional dependence of the PEC of the Ba/Sn glasses are smaller than reported for Zn/Sn glasses which corresponds to the constant NSnOs.

Investigation on the structure and viscosity of BaO-bearing slag melt through molecular dynamics simulation, Raman and 27Al MAS NMR spectra

• BaO addition made the coordination numbers (CNs) of Al-O decreased. • The polymerization degree of slag increased based on the compensation effect. • The competitive action of Ba 2+ and O 2– determined the structure and viscosity. Studying the structure and viscosity of BaO-bearing slag was helpful for explaining the micro mechanism of its physicochemical property variations, and further guiding the utilization of bearing-barium ores for hot metal production. The structure of CaO-SiO 2 -10 wt% MgO-12 wt% Al 2 O 3 -BaO slag with BaO content varying from 0 to 5 wt% was studied based on the combined computational-experimental method, including the molecular dynamic (MD) simulation and experimental measurements of Raman spectroscopy and 27 Al magic angles pinning nuclear magnetic resonance ( 27 Al MAS-NMR) spectroscopy. The viscosity of the slag was measured, and the relationship between the viscosity and polymerization degree of the slag was established. MD simulation results indicated that the coordination numbers (CNs) of Si-O kept unchanged. The concentrations of four-coordinated Al units and bridged oxygen increased with an increase in BaO. The distribution of Q i units of Si and Al indicated that the structural units tended to be more complicated with the increasing BaO content. The result from Raman spectroscopy indicated that the amount of Q 2 and Q 3 units increased with the addition of BaO, while that of Q 0 and Q 1 units decreased. The results from 27 Al MAS-NMR spectroscopy showed that the relative concentration of [AlO 4 ] structural units increased from about 48 to 53 wt%, and an opposite trend was observed in [AlO 5 ] and [AlO 6 ] units, indicating that higher BaO content enhanced the polymerization degree of the slag. In addition, the viscosity of the slag increased with the rising BaO content, which was caused by the dominant effect of Ba 2+ .

Tailoring the structuralism in xBaO·(30–x)Li2O·70B2O3 glasses for highly efficient shields of Gamma radiation and neutrons attenuators

We prepared transparent xBaO·(30–x)Li2O·70B2O3 glasses and investigated their physical properties using UV/vis and radiation shielding. Density and molar volume of the examined glasses increase as BaO content increases. The energy gap and linear refractive index seem to remain stable as BaO concentration increases. These trends are due to the lack in forming NBOs. In these glasses, there is an insulating behavior and the molar refraction increases with increasing BaO content. The single bond strength is almost constant with increasing BaO content which reveals a constancy in polarizability, consequently a constancy in energy gap and refractive index. Numerous criteria were tested to ascertain the glasses’ suitability as radiation shields. The MCNPX code and Phy-X PSD software were used to investigate the gamma shielding potential in the 0.015–15 MeV energy photon range. Glass’s gamma-protective ability increases as the BaO material increases. The BLB30 sample, which contains 30% mol percent BaO, demonstrated the best gamma-ray shielding efficiency. Additionally, the examined glass specimens can be considered a non-toxic alternative for shielding against gamma radiation and neutrons in a variety of nuclear applications.

Viscosity and structure evolution of bearing‐BaO slag melt with the low CaO/SiO2 mass ratio of 0.7

AbstractThe effect of BaO on the viscosity of experimental slag with the CaO/SiO2 ratio of 0.7 was studied based on the rotating cylinder method, and the structure evolution analysis was performed using Fourier transform infrared (FT‐IR), X‐ray photoelectron spectroscopy (XPS) and 27Al MAS‐NMR spectra. The results indicated that the viscosity of molten slag decreased gradually with BaO content rising from 0 wt.% and 5 wt.% due to the dominant effect of free O2‐ rather than Ba2+. The viscous flow activation energy (Eη) of molten slag was calculated, presenting a similar change trend with that of viscosity. The structure analysis demonstrated that, with the increasing BaO content, the [SiO4]‐tetrahedral structures and Si‐O‐Al bonds were destroyed due to an increase in the relative fraction of free oxygen (O2‐). For the Al‐related structural units, the 27Al magic angles spinning nuclear magnetic resonance (27Al MAS NMR) spectra analysis illustrated that the concentration of [AlO4] units reduced, whereas that of [AlO5] and [AlO6] units increased because of the increase of free oxygen and nonbridged oxygen (O0). The results of structure analysis agreed well with the viscosity variations of experimental slag.

Influence of BaO on spectral studies of Cr2O3 doped titanium-boro-tellurite glasses

Abstract Barium-titanium-boro-tellurite glasses containing the transition metal (TM) Cr3+ ions with different BaO mol% were prepared using the melt quenching method. From the XRD, SEM and EDS studies, it was confirmed that the prepared glasses were impurity-free and their atomic arrangement is non-crystalline in nature. The UV–visible spectra exhibited a dominant high absorption band corresponding to the enrgy of ~15974 cm−1 and three weak low-intensity bands around 23641 cm−1, 14881 cm−1 and 14306 cm−1. The identified bands are assigned to 4A2g→4T2g (F), 4A2g→4T1g (F), 4A2g→2T1g (G) and 4A2g→2Eg (G) transitions respectively. The optical band gap values are increasing while the refractive index values are decreasing with increasing BaO content. The crystal-field parameter Dq values and Racah parameter (B) values were found to change non-linearly with the barium oxide content which suggests a change in the environment around Cr3+ ions. From the value of Dq/B, it can be concluded that the Cr3+ ions are localized in the weak crystal field sites. The EPR spectra which were recorded at X-band frequencies exhibited four resonance signals at g 1 ≈ 1.97, g 2 ≈ 2.38, g 3 ≈ 4.25 and g 4 ≈ 5.23. The theoretical g-values were evaluated from the Macfarlane's perturbation formulae. The FTIR and Raman spectra show broad peaks which are the characteristic features of the prepared glass component vibrating modes.

Investigations on borate glasses within SBC-Bx system for gamma-ray shielding applications

This paper examines gamma-ray shielding properties of SBC-Bx glass system with the chemical composition of 40SiO2–10B2O3–xBaO–(45-x)CaO– yZnO– zMgO (where x = 0, 10, 20, 30, and 35 mol% and y = z = 6 mol%). Mass attenuation coefficient (μ/ρ) which is an essential parameter to study gamma-ray shielding properties was obtained in the photon energy range of 0.015–15 MeV using PHITS Monte Carlo code for the proposed glasses. The obtained results were compared with those calculated by WinXCOM program. Both the values of PHITS code and WinXCOM program were observed in very good agreement. The μ/ρ values were then used to derive mean free path (MFP), electron density (Neff), effective atomic number (Zeff), and half value layer (HVL) for all the glasses involved. Additionally, G-P method was employed to estimate exposure buildup factor (EBF) for each glass in the energy range of 0.015–15 MeV up to penetration depths of 40 mfp. The results reveal that gamma-ray shielding effectiveness of the SBC-Bx glasses evolves with increasing BaO content in the glass sample. Such that SBC-B35 glass has superior shielding capacity against gamma-rays among the studied glasses. Gamma-ray shielding properties of SBC-B35 glass were compared with different conventional shielding materials, commercial glasses, and newly developed HMO glasse. Therefore, the investigated glasses have potential uses in gamma shielding applications.

Synthesis and superconducting properties of the MgB2@BaO composites

Synthesis of the magnesium diboride doped by microparticles of barium oxide (MgB2@BaO) composites using a solid-state reaction method has been described. The proposed method gives the possibility to enhance the critical current density of the investigated samples at low temperature in the inert atmosphere. The superconducting parameters (Tc and Jc) have been measured. The influence of the doping agents on superconducting parameters of MgB2 has been analyzed. Obtained results revealed that the best optimal parameters are for 0.7MgB2@BaO sample that shows the highest critical transition temperature 39.3 K and critical current density 1.7*106 A/cm2. It was found that an increasing BaO content leads to the formation of a useful phase of BaB6, which demonstrates positive effects on the superconducting properties, acting as the effective pinning centers.

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.

Sulphide capacity of CaO-SiO2-8%MgO-Al2O3-BaO slags ranging from 0% to 5% in BaO

The sulphide capacities of CaO-SiO2-MgO-Al2O3-BaO slags were measured at 1773 K and 1823 K using the gas-slag equilibration method to estimate the desulphurization ability of the blast furnace slags that contained barium. The effects of basicity, the Al2O3 and BaO content of slags on the sulphide capacity of slags were studied. The relationship between the sulphide capacity and the optical basicity of the slags was also investigated. The experimentally determined results were compared with the sulphide capacities estimated by some previously reported models. The results showed that the sulphide capacity increased significantly when the basicity (CaO/SiO2) increased from 1.0 to 1.2, but decreased when the Al2O3 content increased in the slag. The increasing BaO content increased the sulphide capacity. The desulphurizing ability decreased when the BaO content was more than 3.5%. There was a linearly increasing relationship between the optical basicity and the sulphide capacity. The experimentally determined sulphide capacities were closest to the predicted values obtained by the Sosinsky and Sommerville’s model.

Experimental and theoretical electron paramagnetic resonance and optical studies of Cu2+ spin probe in BaO-TeO2-Bi2O3-B2O3 glass system

Boro-bismuth glasses containing BaO-TeO2 in varying proportions were prepared by the conventional melt quenching method. One mol% of CuO was integrated as the spin probe to the glass systems. The prepared glasses were transparent, bubble-free and light blue in color. The optical absorption spectra revealed two absorption bands corresponding to the transitions 2B1g→2B2gand 2B1g→2E2g respectively. A large anisotropy (Δg = g∥ − g⊥) due to the distortion around the Cu2+ site by the ligands was observed. Experimental and theoretical EPR results have shown that g∥ > g⊥ > A⊥ge (=2.0023) and A∥>A⊥. The ligand field around Cu2+ ions is tetragonally elongated octahedral withdx2−y2 (2B1g) ground state. The decreased peak-to-peak linewidth (ΔB) with increasing BaO content is attributed to decrease in dipolar interaction between the copper ions. The number of EPR active copper ions (N) and the paramagnetic susceptibility (χ) were computed. EPR and optical data were used to τσ determine the bonding parameters α2, β2, β12 and τπ Theoretical investigations were performed using the high order perturbation formulae for 3d9 ions in tetragonally elongated octahedra to determine the spin-Hamiltonian parameters (SHP) and d–d transition bands. The variation of BaO content in the glass matrix had affected the orbital reduction factor, spin-orbit coupling coefficient, cubic and tetragonal field parameters. The Cu2+-O2− octahedron experiences 0.50% elongation along C4 axis. The theoretical and experimental results are well in coincidence within the error limits.

Structure and properties of barium niobophosphate glasses

Phosphate glasses of the ternary system BaO-Nb2O5-P2O5 were studied in two compositional series, namely 40BaO-xNb2O5-(60-x)P2O5 (series A), with x=0–40mol% Nb2O5, and yBaO-20Nb2O5-(80-y)P2O5 (series B), with y=20–60mol% BaO. Nine homogeneous glassy samples were prepared altogether in both series, and their basic physical properties (density, molar volume, glass transition temperature, dilatometric softening temperature and thermal expansion coefficient) were determined. The chemical durability of the Nb2O5-containing glasses is high and the dissolution rate at 80°C is lower than 4–5×10−8gcm−2min−1. The glass transition temperature of the glasses in series A increased significantly with increasing Nb2O5 content from 324 to 727°C, whereas in the series B with increasing BaO content, Tg increased within the range 620–725°C. The index of refraction increased more steeply in glass series A with increasing Nb2O5 content than in the glass series B. According to the Raman spectra in the glass series A, at low Nb2O5 content niobium forms isolated octahedra NbO6 incorporated in the glass network, but when Nb2O5 content increases, these octahedra are linked into chains and further into three-dimensional clusters. In glass series B, NbO6 octahedra form only NbONbO chains connecting NbO6 octahedra. NbO6 octahedra clustering is reflected also in the 31P MAS NMR spectra of BaO-Nb2O5-P2O5 glasses showing on a non-monotonous transformation of phosphate units in the direction Q3→Q2→Q1→Q0, both with increasing Nb2O5 content in the first A series and BaO content in the second B series.

Structure, thermal and spectroscopic properties of Cu2 + ions doped 59B2O3–10K2O–(30-x)ZnO–xBaO (0 ≤ x ≤ 30) glass system

X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), electron paramagnetic resonance (EPR) and optical absorption studies on 59B2O3–10K2O–(30-x)ZnO–xBaO–1CuO glasses (where x=0, 6, 12, 18, 24 and 30mol%) have been carried out. The amorphous nature of the glasses was confirmed using XRD and DSC measurements. The glass transition temperature (Tg) of glass samples has been estimated from DSC traces and found that the Tg increases with increasing BaO content. The IR studies have showed that the present glass system consists of [BO3] and [BO4] units in various borate groups. The spin-Hamiltonian parameters (SHP) such as g||, g⊥, and A|| have been determined from EPR spectra and it was found that the Cu2+ ion is in tetragonal distorted octahedral site with dx2‐y2 as the ground state. Bonding parameters and bonding symmetry of Cu2+ ions have been calculated by correlating EPR and optical data and were found to be composition dependent.

Composition-induced tunable white emission in Ce/Tb/Eu co-doped lithium–barium borophosphate glasses

Ce/Tb/Eu co-doped lithium–barium borophosphate glasses were successfully synthesized by melt quenching method. The structure and luminescence properties of glasses were characterized by Fourier transform infrared spectroscopy, photoluminescence spectra spectroscopy and colorimetric analysis. The influence of matrix composition on glass structure and photoluminescent properties was investigated in detail. The partial replacement of BaO for B2O3 changed the ratios of Ce3+/Ce4+ and Eu2+/Eu3+, and altered the glass structure, which affected the physical properties of the glass samples. The emission intensity of Ce3+, Eu2+ and Tb3+ decreased with increasing BaO content, but the intensity of Eu3+ increased continuously. Energy was transferred from Ce3+, Tb3+and Eu2+ to Eu3+ ions, which resulted in the enhancement of Eu3+ luminescence intensity. Meanwhile, the colors of Ce/Tb/Eu co-doped luminescent glasses changed from cold white to warm white by changing glass matrix composition. Possible mechanisms of the reduction for valence-variable rare earth ions were also discussed.

Raman scattering study of barium borate glasses and melts

Glasses and melts of xBaO–(100−x)B2O3 (x=20, 25, 30, 35, 40, 45, 50, 55, 60 and 67mol%) composition have been prepared and studied using high-temperature Raman spectroscopy. It was shown that the structure of the glassy and molten samples with relatively low concentrations of barium oxide (x=20–35mol%) consists of [B∅4]− charged tetrahedra (∅ is a bridging oxygen atom), B∅2O− asymmetric triangles (O− is a non-bridging oxygen atom) and B∅3 neutral units. The concentration of [B∅4]− tetrahedra (N4) monotonously decreases with increasing BaO content in the melts structure, whereas N4 demonstrates a maximum at x≈40mol% in the glassy samples. B∅O22− pyroborate units appear at x≥40mol%, and BO33− orthoborate anions are also formed in the melts structure when x=60 and 67mol%. The dominant mechanisms for the structural reorganizations generated by changes in temperature depend on the melt composition. The changes in the short range order (SRO) structures can be described by the [B∅4]−⇔B∅2O− isomerization reaction at 25<x<40, whereas the dynamic equilibrium between structural units in the melts with x>50 is most likely described by the 2B∅2O−⇔B∅O22−+B∅3 disproportionation reaction. In both cases, the equilibrium shifts to the right with an increase in temperature. Significant changes in the local structures of melts with a low concentration of barium oxide (x≤20mol%) were not found.

Effects of BaO sintering additive on dielectric properties of Y2Ti2O7 microwave dielectric ceramics

Y2Ti2O7 ceramics of middle-permittivity doped with BaO sintering additive were investigated. Effects of BaO content on the sintering and dielectric properties were evaluated. Pyrochlore Y2Ti2O7 as the main phase and small amount of Ba4Ti13O30 as the second phase were detected by X-ray diffraction patterns (XRD). The sintering temperature decreased obviously with increasing BaO content. The permittivity (ɛ r ) of BaO-doped Y2Ti2O7 ceramics ranged from 54 to 40. Doping with 1 % BaO (mass fraction), the ɛ r value was still over 50. The temperature coefficient of resonant frequency (τ f ) had a trend to zero, especially when 5 % BaO doped, τ f ≈ −7 ppm/°C. The results shows that Y2Ti2O7 ceramics with 1 % BaO addition sintered at 1330 °C exhibited excellent comprehensive performance: ɛ r ≈ 50.3, Q·f ≈ 5978 GHz, τ f ≈ −27 ppm/°C. The ceramics doped with 1 % BaO should be a promising candidate for microwave resonators.

Femtosecond measurement of third-order optical nonlinearities in Bi2O3-B2O3-BaO glasses

We present the measurement of the third-order nonlinearity of Bi2O3-B2O3-BaO glasses using the single Z-scan method with femtosecond laser pulses at 750-850 nm. Both third-order nonlinear refraction γ and two photon absorption coefficient β are investigated. The γ shows an increasing tendency with increasing BaO content, and the largest value is estimated to be 7.2×10-14 cm2/W, which is as large as those of chalcogenide glasses. The dependence of β on the normalized photon energy is studied.

Glass formation and optical band gap studies on Bi2O3-B2O3-BaO ternary system

The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, and the refractive indexes and absorption spectra of samples were measured. It is found that the refractive index of samples as well as the UV absorption increase with the increase of BaO content. According to the Tauc law, optical band gap Eopg which is assumed to be the effective energy band gap Eg is calculated and decreases with the increasing BaO content, and the ratio of Eg/Eopg is 1.3.

Crystallization kinetics of the TeO2–BaO glass system

Tellurite glasses of the system (100–x)TeO2–xBaO, with x = 05, 10, 15 and 20 wt%, have been prepared and studied by differential scanning calorimetry (DSC). The crystallization kinetics of the glasses were investigated under non-isothermal conditions, applying the formal theory of transformations for heterogeneous nucleation to the experimental data obtained by DSC, using continuous-heating techniques. In addition, from the dependence of the glass-transition temperature (T g) on heating rate, the activation energy for the glass transition was derived. Similarly, the activation energy of the crystallization process was determined and the crystallization mechanism characterized. The thermal stability of these glasses are considered in terms of the characteristic temperatures, T g and T in (the onset temperature of crystallization), via ΔT = T in−T g and a kinetic parameter K(T g). The results confirm that thermal stability decreases with increasing BaO content. The phases into which the glass crystallizes have been identified by X-ray diffraction. Diffractograms of the transformed material indicate the presence of microcrystallites of α-TeO2, γ-TeO2 and BaTeO3 in the remaining amorphous matrix.