Effect of Barium Oxide on the Formation and Coexistence of Tricalcium Silicate and Calcium Sulphoaluminate

Formation and coexistence of tricalciurn silicate （C3S） and calcium sulphoaluminate （ C4 A3S^- ） minerals in Portland cement clinker containing calcium sulphoaluminate were investigated. Thef-CaO content, mineral composite and formation of mineral in the clinker were analyzed respectively by chemical analysis, differential scanning calorimetry（DSC） and X-ray diffraction. The results show that, adding a suitable amount of BaO can improve the burnability of raw meal and promote the f-CaO absorption. Tricalcium silicate and calcium sulphoaluminate minerals can form and coexist in clinkers at 1 234-1 317 ℃ by the addition of BaO to the raw meal. A suitable amount of BaO expanded the coexistence temperature of two minerals by 58 ℃.

Electric-magnetic-force characteristics of rare earth barium copper oxide superconductor high-field coils based on screening effect and strain sensitivity

Rare earth barium copper oxide(REBCO)is the most researched and commercialized second-generation high-temperature superconducting material.Due to the anisotropic structure,strong deformation sensitivity,and central field errors caused by screening current effects,it is still a challenge for commercialization applications.In this study,the transversely isotropic constitutive relationship is selected as the mechanical model based on the structural characteristics of REBCO tapes,and suitable microelements are selected to equate the elastic constants using their average stress-strain relationships.Then,a two-dimensional axisymmetric model for coils wound by single-layer tapes is constructed to analyze the dependence of the electric-magnetic-force distribution in the tape on the strain.Finally,the anisotropic approximation of the homogenized bulk method is used to equate large-turn high-field coils,and the electric-magnetic-force distribution characteristics of the coils with/without screening effects and mechanical strain conditions are investigated,respectively.The results reveal that the mechanical strain has a weakening effect on the electromagnetic field distribution of superconducting tapes,but causes a significant enhancement in the force field distribution.In the presence of 0.5% mechanical strain,the maximum weakening of the peak value of the current density and the critical current density inside the high-field coil can reach about 8% and 13%,respectively,with a nearly 5 times increase in the peak stress.The screening current makes the current field distribution inside the coil improve by about 10 times.The screening current induced magnetic field can reach up to 0.8 T,making the relative error of the high-field coil center up to 7.8%.

Quench characteristics and mechanical responses during quench propagation in rare earth barium copper oxide pancake coils

Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,and a two-dimensional(2D)axisymmetric electro-magneto-thermal model is presented.The effects of the constituent materials,background field,and coil size are analyzed.An elastoplastic mechanical model is used to study the corresponding mechanical responses during the quench propagation.The variations of the temperature and strain in superconducting layers are compared.The results indicate that the radial strain evolutions can reflect the transverse quench propagation and the tensile hoop and radial stresses in superconducting layers increase with the quench propagation.The possible damages are discussed with the consideration of the effects of the background field and coil size.It is concluded that the high background field significantly increases the maximum tensile hoop and radial stresses in quenching coils and local damage may be caused.

Photocatalytic Degradation of Oxytetracycline Dihydrate from Aqueous Solution Using Nano ZnO and ZnO.xBaTiO3 (x = 3%, 18%, 33% and 48%)

Traditional wastewater mostly contains pharmaceutical ingredients. Therefore, the wastewater must be completely free from antibiotics before its release into the environment. In the present study, photocatalytic degradation was done to investigate the removal efficiency of Oxytetracycline Dihydrate (OTC) using ZnO, ZnO/3%BaTiO3 (3 BZ), ZnO/18%BaTiO3 (18 BZ), ZnO/ 33%BaTiO3 (33 BZ) and ZnO/48%BaTiO3 (48 BZ) under UV light. After the exposure time of 420 min, about 99.57% and 97.87% of OTC was degraded using ZnO and 3 BZ respectively. Further, increasing the amount of BaTiO3 in ZnO prolongs the degradation time. Therefore, faster efficiency was found using ZnO nanoparticles. The observed reaction rate constant using ZnO was 0.00933 min-1 which decreased to 0.00532 min-1 using 48 BZ, indicating the decrease of reaction rate for increasing the amount of BaTiO3. Hence, the use of ZnO photocatalyst is anticipated to be a promising technique for the photocatalytic degradation of contaminated wastewater with oxytetracycline antibiotics using UV light.

Phase Behavior of BaLn_2Mn_2O_7 (Ln=Rare Earth) with a Layered Perovskite Structure

Many phases appear in BaLn 2Mn 2O 7 family (Ln=rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K 2NiF 4 type structure, although the X-ray diffraction patterns are clearly different: a little deformation or tilting of the oxygen octahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb 2Mn 2O 7, was refined including the data of high temperature X-ray diffractometry.

Development of Second Generation High T_C Superconducting Tapes

Owing to the high performance, the second generation （2 G） high Tc superconducting tapes based on yttrium barium copper oxide have attracted much attention of the researchers worldwide to develop the processing techniques for application. In recent years, a series of the achievements have made the 2 G tapes become the focus of the superconductor research. An overview of the recent progress of 2 G superconductor tapes was provided,

Syntheses，Structures and Properties of Some New Composition Perovskite Compounds：Sr0．6Bi0．4FeO2．7，Sr1－xBixFeO3－y and Ba1．5Pt0．5Mn2O6

New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.

Effect of BaO on catalytic performance of Pd-based catalysts for purification of gasoline-methanol exhaust

Barium oxide was developed successfully to modify palladium catalysts supported on CeO2-ZrO2-La2O3-Al2O3（CZLA） compound oxides by impregnation method. N2 adsorption（BET）, X-ray diffraction（XRD）, H2-temperature-programmed reduction（H2-TPR） and X-ray photoelectron spectroscopy（XPS） were employed to characterize the influence of BaO on the physicochemical properties of catalyst. And catalytic activity tests for methanol, CO, C3H8 and NO conversion were evaluated. Catalytic activity results showed that BaO had a positive effect on the conversion of all pollutants. H2-TPR results suggested that the addition of BaO increased the reductive ability of the palladium catalysts. The XPS results indicated that doping BaO also improved the dispersion of Pd species and increased the amounts of Ce3＋ on the Pd-Ba/CZLA catalyst surface, which led to a better redox property. The excellent redox property helped to improve the catalytic activities toward all the pollutants over Pd-based catalysts.