Papers by Keyword: BaO

Abstract: In this work, the glass formula (70-x)P₂O₅: 15NaF: 5ZnF₂: 15AlF₃: xBaO where x is 0, 5, 10, 15 mol% were manufactured by the conventional melt-quenching technique at 1200 °C in 3 hours for photon shielding application. The effect of glasses was examined on the physical, gamma ray and x-ray shielding properties. The results revealed that the density was increased with increasing of BaO concentrations. The glass systems were calculated by using the experiment set up for estimating the radiation shielding properties in the content of mass attenuation coefficients (μ_m), effective atomic number (Z_eff), and effective electron density (N_eff), which were increased when concentrations of BaO increased, while the half value layer (HVL) was decreased. For result of using the x-ray source, the linear attenuation (μ) was increased with an accrue in BaO concentration. The HVL was decreased when concentrations of BaO increased. The HVL values of glass samples at 15 mol% has better shielding behavior than the standard materials at 120 kVp. The BaO glass systems can be candidate for radiation shielding materials in the future.

Abstract: In order to eliminate the hazards of fluoride, the low melting point and boosting substances of Li₂O, BaO, B₂O₃ were added into the low C peritectic steel mold powder replaced fluoride. It makes fluorine-free protection slag successfully developed. The crystalline ore phase of Fluorine-free mould slag is melilite. By adjustment crystallization ratio of melilite in slag film, the heat flow through the mold can be controlled.

Abstract: The effect of barium on the formation, structure and phase transition of tricalcium silicate (C₃S) has been studied by X-ray powder diffraction combined with Rietveld method, Differential scanning calorimetry and Fourier transform infrared spectroscopy. The results showed that the low contents of barium was favorable the formation of C₃S with up to 1.5% BaO. Higher amounts of BaO inhibited the C₃S crystallization and lead to preferential formation of dicalcium silicate solid solution. Three triclinic forms T1, T2 and T3 of C₃S were stabilized. The lattice parameters changed linearly to the barium content, however the discontinuity appeared at the phase transformation boundary, which follows the Vegards law. The crystallographic structure of T1 and T2 was similar to that of T3. The SiO₄^4- tetrahedra were distorted in T1 and T2, while that was approximately regular tetrahedron in T3. The phase transitions of C₃S were influenced by the incorporation of barium. It was believed that the stabilization of high temperature polymorphs of C₃S was related to the lattice distortion caused by ionic substitution.

Abstract: CuO has been doped solely and together with BaO and SiO₂ into barium titanate by mixing and calcination. X-ray diffraction showed that the sample doped by CuO-BaO has stable second hexagonal phase while the samples doped by CuO, CuO-SiO₂ were of a pure perovskite phase. For CuO-BaO doping, the Curie temperature was decreased accompanied with higher εmax; while for CuO doping and CuO-SiO₂ codoping, the Curie temperature was increased with εmax decreased. The difference can be explained considering that Cu²⁺ ion could not only incorporate into the BaTiO₃ lattice, but also assemble in the boundary phase when CuO was doped solely. Besides, the mechanisms of CuO doping and SiO₂ doping could happen at one time.

Abstract: Effect of doped BaO on the formation dynamics of alite of alite-rich cement clinker was investigated. The experimental results indicated that its formation kinetic satisfied with three- dimensional spherical model and accorded with Glinstling diffusion equation. Doped BaO could decrease dramatically the apparent activation energy of alite-rich cement clinker. This was contributed to the combination of C₂S and CaO in liquid phase, and acceleration of formation of alite-rich cement clinker.

Abstract: In order to reduce fluorine pollution, partial fluoride could be replaced by BaO in mould flux. The effects of BaO on melting temperature, viscosity, fluidity, surface tension, Al₂O₃ inclusion and adsorption of low fluoride content mould flux for high speed continuous casting were studied, as well as the effect of basicity on crystallization property. The results showed that with the increase of BaO content, melting temperature, viscosity and surface tension of mould flux decreased obviously, and fluidity and Al₂O₃ inclusion adsorption increased. Partial fluoride could be replaced by BaO in mould flux. The BaO content should be less than 4 per cent so that it can play an effective role. The basicity had great influence on crystallization property.

Abstract: ZnO-BaO particles (4-10) nm have been synthesized by applying 40 KHz ultrasonic wave simultaneously with the co-precipitation process of Zn and Ba oxalate at 50 0C. DTA curves of the co-precipitate were carried out and the decomposition temperature was determined. Mixed oxide obtained from thermal decomposition of Zn2 Ba (C2O4)2.2H2O in air has been investigated by TEM, XRD, IR and UV-Vis measurements. The results revealed that the obtained particle consists of a core of highly deformed Ba contaminated ZnO nano-crystals. The ZnO crystalline core is coated by Ba rich amorphous layer which prevents its growth. Decreasing concentration of ZnCl2 in the precipitation solution from 0.1M to .05 M leads to decrease the size of the particle from (10-20) nm to(4-10) nm, in average, increases UV cut-off, the cut-off tail and rounded of the shape of the particle.