Effect Of BaO Research Articles

Structural Interaction between BaO and Al2O3 in Aluminosilicate Slags

The effect of BaO and Al2O3 on the viscosity of SiO2–CaO–MgO–Al2O3–BaO slag from 1673 to 1873 K is studied by the rotating cylinder method. The structure of slag is examined by Raman spectroscopy and molecular dynamics simulation. In this study of viscosity, Al2O3 shows amphoteric oxide characteristics and BaO shows characteristics different from the basic oxide. The viscosity increases as the BaO increases from 2 to 4 wt% in the slag with CaO/SiO2 = 1.07. However, the viscosity decreases when the BaO content increases from 6 to 8 wt%. From molecular dynamics simulations and Raman analysis, the increase in BaO content leads to a greater aggregation of Al around Ba atoms and increases the number of Al–O bonds. This indicates that higher BaO content promotes the polymerization of the [AlO4] tetrahedral structure. Furthermore, a good quantitative relationship between viscosity and the ratio of Q3/Q2 of the Raman spectrum of the slag is observed.

Physical, Mechanical, and ionizing radiation shielding properties of 10PbO–10Na2O-(80-x)B2O3-xBaO glasses

This research explored the mechanical, physical, and ionizing radiation shielding properties of 10PbO–10Na2O-(80-x)B2O3-xBaO glass samples, where x = 10, 15, 20, and 25. The conventional melt-quench technique was employed to prepare the samples. The elastic moduli were investigated using the Makishima–Mackenzie model. At the same time, the radiation shielding properties involved a comprehensive analysis of the effective atomic number, linear attenuation and mass attenuation coefficients, half-value and tenth-value layers, radiation protection efficiency, and transmission factors, as well as the buildup factors for different mean-free paths (mfp). The impact of BaO (mol%) on the parameters mentioned above was investigated across a range of photon energies (0.015–15 MeV). In addition, the effect of BaO on the physical and mechanical properties of current glasses was studied. The addition of BaO showed an inverse impact on mechanical and physical properties, gradually reducing the glass's stability. In contrast, adding BaO to the compound enhanced photon attenuation ability, which means the sample with 25% BaO had the optimum capacity for radiation shielding amongst all the prepared samples. Moreover, the results demonstrated the complex interplay of Compton scattering, pair production, and the photoelectric effect, influencing the attention of photons. This work provides beneficial intuition into designing and optimizing glass-based radiation shielding materials.

Effect of BaO and MgO on structure and properties of aluminate slag with various CaO/Al2O3 ratios

Effect of BaO and MgO on structure and properties of aluminate slag with various CaO/Al2O3 ratios

Effect of BaO and Li2O on Basic Characteristics of Mold Fluxes with Different Basicity

Effect of BaO and Li2O on Basic Characteristics of Mold Fluxes with Different Basicity

Effect of BaO on Formation Mechanisms of Silico-ferrite of Calcium and Aluminum

Effect of BaO on Formation Mechanisms of Silico-ferrite of Calcium and Aluminum

Effect of BaO on crystallization, sintering, and properties of MgO-Al2O3-SiO2 glass–ceramics

Effect of BaO on crystallization, sintering, and properties of MgO-Al2O3-SiO2 glass–ceramics

Effect of BaO on the structure and luminescence properties of Eu3+doped GSRG glass

Eu3+ doped GeO2-SiO2-RO (R=Mg, Ca, Ba)-Ga2O3 (GSRG) glass was prepared by high temperature melting method. Through XRD, absorption spectrum, fluorescence spectrum, fluorescence lifetime, infrared spectrum and other test methods, the influence of BaO on the structure and luminescence properties of Eu3+ doped GSRG glass was studied. The results show that BaO in RO (R=Mg, Ca, Ba) can make Eu3+ doped GSRG glass have higher luminous intensity. As BaO gradually replaces MgO, the luminous intensity of glass first increases and then decreases with the increase of BaO concentration. The luminous intensity reaches its peak when the BaO concentration reaches 25 mol%. Meanwhile, the transition from germanium-oxygen tetrahedron [GeO4] to germanium-oxygen octahedron [GeO6] appeared in the glass structure, again by [GeO6] shift back to [GeO4]. The CIE chromaticity coordinates show that the color temperature of prepared glass is 1700–1800 K, and the color purity is above 98%.

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.

Viscosity and structure evolution of CaO–SiO2–MgO–Al2O3–BaO slag with the CaO/SiO2 mass ratio of 0.9

Keeping a low and steady viscosity of slag is conducive to smooth operation of blast furnace. In this work, the effect of BaO on the viscosity and structure evolution of CaO–SiO2–MgO–Al2O3–BaO slag with a fixed CaO/SiO2 mass ratio of 0.9 was studied. The results revealed that the viscosity decreased firstly with BaO content rising from 0 wt% to 1.0 wt%, and then increased with further improving BaO content, which was ascribe to the contradictory effect of Ba2+ and O2− on the aluminate–silicate network structure. The structural analysis by Fourier transform infrared spectroscopy (FTIR) and Raman spectra showed that a small amount addition of BaO could promote the transformation from Q2 and Q3 units toward Q0 and Q1 units. However, the higher BaO content would induce an increasing concentration of Q2 and Q3 units, leading to an enhancement of the polymerization degree of slag. In addition, the variations of Al-related structural units were identified by the 27Al magic angle spinning nuclear magnetic resonance (27Al MAS-NMR) spectra. The relative fraction of [AlO4] units firstly decreased and then increased with the addition of BaO, and an opposite trend was observed for [AlO5] and [AlO6] units. The structural analysis supported the results of viscosity experiment well.

Effect of BaO and MnO on high-temperature properties and structure of blast furnace slag

The viscosity of slags with different contents of BaO and MnO was measured by the rotating cylinder method. The high-temperature melting characteristics of the slag were studied by TG-DSC, and the change of melting enthalpy and melting temperature of the slag was also detected. The structural properties of the slag were characterized using Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman). The results show that in the range of 0-3wt%, the melting enthalpy of slag increases with the increase of BaO content and the melting temperature of slag has a slight tendency to decrease. With the increase of MnO content, the slag melting enthalpy and melting temperature decreased significantly. FT-IR and Raman results show that with the increase of BaO concentration, led to the polymerization of [AlO4]− and [SiO4]− tetrahedral units. MnO depolymerizes the structure of slag by breaking the bond between silicate and aluminate, which may lead to the decrease of slag viscosity. However, the influence of MnO on the aluminate structure is minor.

Effect of BaO on Hydrogen Sorption Performance of Mg17Al12: Experimental and Theoretical Studies.

The Mg17Al12-BaO composite is synthesized via mechanical milling and the effect of BaO on the hydrogen sorption properties of Mg17Al12 is studied. Experimentally, we prepare the Mg17Al12-Ba, Mg17Al12-BaO, Mg17Al12-BaF2, and Mg17Al12-BaCl2 mixtures and find that the Mg17Al12-BaO composite shows a superior hydrogen storage performance. For instance, the hydrogenation (dehydrogenation) enthalpy of the Mg17Al12 decreases from 62.4 (91.2) to 58.6 (71.7) kJ mol-1 after adding BaO. When 1.0 wt % of H2 is absorbed/desorbed, the hydrogen absorption/desorption temperature of the Mg17Al12-BaO is 181/271 °C, which is 73/37 °C lower than that of the Mg17Al12. Furthermore, the catalytic mechanism of BaO on the hydrogenation of Mg17Al12 (110) surface is investigated by density functional theory (DFT). Calculations indicate that compared with the Mg17Al12 (110) surface, the adsorption energy and dissociation barrier of hydrogen on the Mg17Al12-BaO (110) surface are both improved significantly. Our experimental and theoretical results are helpful for understanding the effect of metal oxide on hydrogen storage properties of Mg17Al12.

Effect of BaO on lead free zinc barium tellurite glass for radiation shielding materials in nuclear application

In this study, the zinc barium tellurite glasses (ZBaT) synthesized and inspected their radiation defensive mechanism and structural behavior. Glass composition (90-x) TeO2 - 10 ZnO - xBaO, where 25≤ x ≤ 35 (mol%) was prepared using the melt quenching technique and glass-forming pseudo-ternary diagram was discussed. Addition of BaO enhances the polarization in the present glasses there by it increases the bond length hence glass network expands resulting in volume. The mass attenuation coefficient (μm) of ZBaT glasses have been evaluated at various energies via Compton scattering technique. The results found that the μm, effective atomic number and effective electron density decrease with the increase in γ-ray energies which is in a good agreement with theoretical values attained using Geant4 and WinXCOM. At 25 mol% BaO content the glass samples show less mean free path (MFP) which were compared with other standard shield defensive materials. The obtained results reveal that the formation of non-bridging oxygens increased with higher concentration of BaO. The transmission spectra of the prepared glasses displayed optical light transparency thereby demonstrating their efficient role being transparent window when used as radiation defensive material without Pb component proving them as eco-friendly for environment.

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.

Radiation attenuation and optical features of lithium borate glasses containing barium: B2O3.Li2O.BaO

The influence of BaO on the optical characteristics and nuclear radiation shielding properties for 60B2O3-(40-x)Li2O-xBaO: x = 0, 5, 10, 15, and 20 mol% glasses was investigated. Various optical parameters such as optical transmission and reflection loss (TOptical, RLoss), molar refraction and molar polarizability (RMolar, αMolar), optical and static dielectric coefficients and metallization criterion (εOptical, εStatic, MCriterion), and metallization property according to refractive index and optical energy gap (M(nLinear), M(EOptical)), were determined. The results confirmed that RMolar changes directly with αMolar, while TOptical changes inversely with RLoss. The mass attenuation coefficient (μ/ρ) was investigated using WinXCOM software and the results showed that all the S1–S5 glasses have good attenuation ability at 284 keV due to their high mass attenuation coefficients (μ/ρ). The highest and lowest values of μ/ρ occurred at 284 keV and 1.33 MeV respectively and varied between 0.1055 and 0.1361 cm2/g and 0.0526–0.0534 cm2/g. The linear attenuation coefficient (μ) increased with the gradual addition of BaO from glass S1→S5. The results showed that the effective atomic number (Zeff) for S1 is almost constant, while S5 possessed the highest Zeff values. The half value layer (HVL) was estimated and the effect of BaO on this parameter was analyzed. At 284 keV, the HVL values were 2.8192, 2.3847, 2.1597, 1.9687 and 1.8936 cm for S1–S5 glasses respectively. The S5 sample possessed the least HVL, and accordingly, had better attenuation capabilities than the S1–S4 samples. Therefore, lithium borate glasses with high concentration of BaO can be applied in several optical and medical applications.

Effect of BaO on the viscosity and structure of fluorine-free calcium silicate-based mold flux

The effect of BaO on the viscosity and structure of fluorine-free calcium silicate-based mold flux was studied using a rotary viscometer, molecular dynamics (MD) simulation, and Raman spectroscopy. The results demonstrated that the viscosity, activation energy, and break temperature of the samples decreased with the addition of BaO. The MD simulation revealed that the network breakers of BaO readily offered O2− to decrease the degree of polymerization of the network formers of SiO2 and Al2O3 in melts. The results of the Raman spectroscopy demonstrated that the complex network structure of [SiO3]2− (chain) and [Si2O5]2− (sheet) was depolymerized to the simple structure of [Si2O7]6− (dimer) and [SiO4]4− (monomer) with an increasing content of BaO. The results of the Raman spectroscopy were consistent with the MD simulation; thus, in conclusion, the complex network structure was depolymerized to the sample structure, resulting in a decrease in viscosity with the addition of BaO.

Effect of BaO on mechanical and hydration characteristic of C8A6P as predominant mineral in phosphoaluminate cement

Phosphoaluminate cement clinker (PAC) was one type of cementitious material due to its high durability and mechanical performance. As the predominant mineral phase in PAC, the high-temperature formation and property of calcium phosphoaluminate mineral (C8A6P) were related closely with hydration and mechanical characteristic for PAC. Thus, the influence of BaO on the performance of C8A6P mineral phase was investigated carefully in this paper. It was found that BaO of 17.5–20% content could endow C8A6P mineral with predominant mechanical performance. This was due to the fact that C8A6P mineral was activated by BaO. Excessive BaO would lead to the formation of new unexpected phase BaO·Al2O3. The limited solid solubility of BaO in C8A6P mineral was 20%. The addition of BaO changed the ratio of hydration products of C2(A,P)H8 and C(A,P)H10 for C8A6P mineral.

Novel gallate‐based oxide and oxyfluoride glasses with wide transparency, high refractive indices, and low dispersions

AbstractThe glass‐forming region of a BaO‐La2O3‐Ga2O3 ternary system was confirmed and BaF2‐BaO‐La2O3‐Ga2O3 new oxyfluoride glasses were prepared by a containerless processing. We also analyzed the physical, thermal, and optical properties of new oxide and oxyfluoride glasses. The direct effects of the substitution of oxygen by fluorine and the effect of BaO and La2O3 on the refractive index and Abbe number were discussed on the basis of electronic polarizability and resonance wavelength of oscillator. The refractive indices increased with increasing La2O3 concentration because La2O3 increased the electronic polarizabilities. Abbe number increased with increasing BaO and fluorine concentration because of the decrease in resonance wavelength of oscillator. By the combination of the BaO, La2O3, and fluorine in the gallate glass system, we could obtain novel oxide and oxyfluoride glasses with high refractive index (1.81‐1.95) and high Abbe number (31‐55). The absorption edge in UV region shifted to the shorter wavelength and IR cut‐off wavelength shifted to the longer wavelength with increasing fluorine. Therefore, wide transparent glass was obtained from 262 nm to 11.3 μm.

Effect of BaO on thermal and mechanical properties of alkaline earth borosilicate glasses with and without Al2O3

BaO-CaO-Al2O3-SiO2 (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 50 mol%[SiO2-B2O3]-xBaO-(45-x)CaO-5Al2O3 with x = 0, 10, 20, 25, 30, 35 and 40 mol%, represented as BCBSA and another without Al2O3 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.

Effect of BaO on the phase composition and properties of aluminates for Ba-W cathodes

In this study, we prepared (4.8+x)BaO·CaO·2Al2O3 (0 ≤ x ≤ 1.6) aluminates by calcining the precursors under static air at 1500 °C for 120 min. The precursor powders were prepared using a liquid phase co-precipitation method. The effects of the molar content of BaO on the phase composition (before and after melting), melting properties, environmental stability, evaporation, and emission properties of the aluminates was investigated systematically The results showed that the phase of the aluminates completely transformed from Ba5CaAl4O12 to Ba3CaAl2O7 with an increase in the BaO content. After melting, the phase changed from Ba5CaAl4O12 to a mixed phase of Ba5CaAl4O12 and Ba3CaAl2O7. In the high-temperature molten state, the aluminates were in the ionic state, which generated a relatively low-energy Ba5CaAl4O12 phase during cooling crystallization. With every 0.4 mol increase in the BaO content, the initial melting temperature of the aluminates decreased by 10–20 °C, while the environmental stability deteriorated gradually. When the aluminates reacted with H2O and CO2 in the air, the original phase still existed and the characteristic peaks gradually broadened, but with the formation of Ca(OH)2, CaCO3, and BaCO3. At 1050 °C, with an increase in the BaO content, the evaporation rate of the Ba-W cathodes increased and the emission current density first increased and then decreased. The main components of the Ba-W cathode evaporation were Ba and BaO. At n(BaO):n(CaO):n(Al2O3) = 6:1:2, the Ba-W cathode showed the best emission performance, and its pulse emission current density at 1050 °C was as high as 35.31 A/cm2.

Effect of BaO on the calcination and hydration characteristic of CA

Phosphoaluminate cement (PAC) clinker had good mechanical properties at early and long-term period. In comparison, the compressive strength of PAC clinker modified by BaO was more prominent. As primary mineral phase for PAC clinker, CA’s mineralogical structure and hydration characteristics were intimately related to the compressive strength of hardened cement paste. In this study, the effects of BaO content on the calcination, mineralogical structure and hydration characteristics of CA were investigated. Experimental results showed that the appropriate calcination temperature of CA was 1400 °C. No more than 11% (the substitution ratio of BaO for CaO) addition of BaO can promote the conversion of C12A7 to CA and increase the formation ratio of CA. Appropriate content of 7 mol% BaO could endow the hardened paste with excellent compressive strength. In CA mineral phase the high limit addition of BaO was 15 mol%. The addition of BaO decreased and even restrained the formation of C2AH8 and C3AH6 of CA hydration products and also improved the content of CAH10. The addition of BaO dramatically decreased the hydration velocity and cumulative heat of CA mineral.