The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray d...The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray diffraction method and scanning electron microscope was also employed to observe the surface morphologies. It is found that （La,Sb）-codoped barium strontium titanate ceramics exhibit typical perovskite structure and the average grain size decreases dramatically with increasing the content of Sb2O3. Both La3＋ ions and Sb3＋ ions occupy the A-sites in perovskite lattice. The dielectric constant and dielectric loss of barium strontium titanate based ceramics are obviously influenced by La2O3 as well as Sb2O3 addition content. The tetragonal-cubic phase transition of La2O3 modified barium strontium titanate ceramics is of second order and the Curie temperature shifts to lower value with increasing the La2O3 doping content. The phase transition of （La,Sb）-codoped barium strontium titanate ceramics diffuses and the deviation from Curie-Weiss law becomes more obvious with the increase in Sb2O3 concentration. The temperature corresponding to the dielectric constant maximum of （La,Sb）-codoped barium strontium titanate ceramics decreases with increasing the Sb2O3 content, which is attributed to the replacement of host ions by the Sb3＋ ions.展开更多
SrTiO3 submicro-wires were prepared by the reaction of layered titanatc nanowircs with Sr（OH）2 powder in an autoclave. The wires were investigated using X-ray diffraction （XRD）, scanning electron microscope （SEM...SrTiO3 submicro-wires were prepared by the reaction of layered titanatc nanowircs with Sr（OH）2 powder in an autoclave. The wires were investigated using X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM）, Ultra-violet visible （UV-vis）, photoluminescence （PL） and Raman spectroscopy. The XRD measurement shows that the prepared SrTiO3 submicro-wircs hardly have impurity phases. The SEM and TEM images demonstrate that the scalable wires, which need to be processed at the reaction temperature of 180℃ for about 48 hours, are not composed of single crystals. The PL shows that the wire-like SrTiO3 has emission peaks at the wavelengths of 568 and 585 nm. Further, the Raman spectroscopy reveals structural changes in the products through different reaction time.展开更多
The low O^(2-)diffusion rate in the electro-deoxidation of titanium containing compounds by either the OS process or the FFC process leads to a low reaction speed and a low current efficiency.In this study,Ca_(3)Ti_(2...The low O^(2-)diffusion rate in the electro-deoxidation of titanium containing compounds by either the OS process or the FFC process leads to a low reaction speed and a low current efficiency.In this study,Ca_(3)Ti_(2)O_(7) was used as a precursor to improve the reduction speed of titanium.Because of the greater number of"diffusion channels"created in cathode as Ca^(2+) liberates from Ca_(3)Ti_(2)O_(7) precursor in the electrodeoxidation process,the O^(2-)diffusion rate was improved significantly by using Ca_(3)Ti_(2)O_(7) instead of CaTiO3 as precursor.Parallel constant voltage electrolysis(3.2 V)confirms that Ca_(3)Ti_(2)O_(7) and CaTiO3 are reduced simultaneously because of their similar crystal structures.However,the reduction area of Ca_(3)Ti_(2)O_(7) spreads much faster than that of CaTiO3,indicating a difference in the O^(2-) diffusion rate.Constant voltage cyclic voltammetry(CV)and theoretical analysis of the crystal structure were also conducted to compare the differences between Ca_(3)Ti_(2)O_(7) and CaTiO3.The results indicate that using a precursor with a greater number of soluble cations,titanium reduction speed can be greatly improved in the electro-deoxidation process.Finally,a new electrolysis method for converting and recycling excess CaO from the Ca_(3)Ti_(2)O_(7) precursor was proposed.展开更多
The magnetically separable ternary polyetherimide/titanate@Fe3O4(PTF) photocatalysts of special heterostructure between magnetite(Fe3O4) microspheres and titanates nanosheets modified by polyetherimide(PEI) were succe...The magnetically separable ternary polyetherimide/titanate@Fe3O4(PTF) photocatalysts of special heterostructure between magnetite(Fe3O4) microspheres and titanates nanosheets modified by polyetherimide(PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe3O4microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3 D microsphere and 2 D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe3O4microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe3O4microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe3O4microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5(96.7%) over 3 times reuse.展开更多
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 degra...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%BaTiO<sub>3</sub> (3 BZ), ZnO/18%BaTiO<sub>3</sub> (18 BZ), ZnO/ 33%BaTiO3 (33 BZ) and ZnO/48%BaTiO<sub>3</sub> (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 BaTiO<sub>3</sub> 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<sup>-1</sup> which decreased to 0.00532 min<sup>-1</sup> using 48 BZ, indicating the decrease of reaction rate for increasing the amount of BaTiO<sub>3</sub>. 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.展开更多
TITAN 3D Geo-view是近年来迅速发展起来的一门地学数据与计算机相结合的新型地学信息科学技术,它把现实世界中对象的地质位置和相关属性有机地结合起来,满足用户对地学信息的管理,并借助其特有的地学数据分析功能和可视化表达,进行各...TITAN 3D Geo-view是近年来迅速发展起来的一门地学数据与计算机相结合的新型地学信息科学技术,它把现实世界中对象的地质位置和相关属性有机地结合起来,满足用户对地学信息的管理,并借助其特有的地学数据分析功能和可视化表达,进行各种辅助决策。展开更多
基金Project (11KJB430007) supported by the University Natural Science Research Program of Jiangsu Province, ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray diffraction method and scanning electron microscope was also employed to observe the surface morphologies. It is found that （La,Sb）-codoped barium strontium titanate ceramics exhibit typical perovskite structure and the average grain size decreases dramatically with increasing the content of Sb2O3. Both La3＋ ions and Sb3＋ ions occupy the A-sites in perovskite lattice. The dielectric constant and dielectric loss of barium strontium titanate based ceramics are obviously influenced by La2O3 as well as Sb2O3 addition content. The tetragonal-cubic phase transition of La2O3 modified barium strontium titanate ceramics is of second order and the Curie temperature shifts to lower value with increasing the La2O3 doping content. The phase transition of （La,Sb）-codoped barium strontium titanate ceramics diffuses and the deviation from Curie-Weiss law becomes more obvious with the increase in Sb2O3 concentration. The temperature corresponding to the dielectric constant maximum of （La,Sb）-codoped barium strontium titanate ceramics decreases with increasing the Sb2O3 content, which is attributed to the replacement of host ions by the Sb3＋ ions.
基金Scientific Research Foundation for the Returned Over-seas Scholar from the State Education Ministry, China
文摘SrTiO3 submicro-wires were prepared by the reaction of layered titanatc nanowircs with Sr（OH）2 powder in an autoclave. The wires were investigated using X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM）, Ultra-violet visible （UV-vis）, photoluminescence （PL） and Raman spectroscopy. The XRD measurement shows that the prepared SrTiO3 submicro-wircs hardly have impurity phases. The SEM and TEM images demonstrate that the scalable wires, which need to be processed at the reaction temperature of 180℃ for about 48 hours, are not composed of single crystals. The PL shows that the wire-like SrTiO3 has emission peaks at the wavelengths of 568 and 585 nm. Further, the Raman spectroscopy reveals structural changes in the products through different reaction time.
基金the National Natural Science Foundation of China(Nos.51604255 and U1702251)。
文摘The low O^(2-)diffusion rate in the electro-deoxidation of titanium containing compounds by either the OS process or the FFC process leads to a low reaction speed and a low current efficiency.In this study,Ca_(3)Ti_(2)O_(7) was used as a precursor to improve the reduction speed of titanium.Because of the greater number of"diffusion channels"created in cathode as Ca^(2+) liberates from Ca_(3)Ti_(2)O_(7) precursor in the electrodeoxidation process,the O^(2-)diffusion rate was improved significantly by using Ca_(3)Ti_(2)O_(7) instead of CaTiO3 as precursor.Parallel constant voltage electrolysis(3.2 V)confirms that Ca_(3)Ti_(2)O_(7) and CaTiO3 are reduced simultaneously because of their similar crystal structures.However,the reduction area of Ca_(3)Ti_(2)O_(7) spreads much faster than that of CaTiO3,indicating a difference in the O^(2-) diffusion rate.Constant voltage cyclic voltammetry(CV)and theoretical analysis of the crystal structure were also conducted to compare the differences between Ca_(3)Ti_(2)O_(7) and CaTiO3.The results indicate that using a precursor with a greater number of soluble cations,titanium reduction speed can be greatly improved in the electro-deoxidation process.Finally,a new electrolysis method for converting and recycling excess CaO from the Ca_(3)Ti_(2)O_(7) precursor was proposed.
基金Funded by the National Natural Science Foundation of China(Nos.21103054,21003055,and 50872037)the Open Fund of Fujian Provincial Key Laboratory of Functional Materials and Applications(Xiamen University of Technology)(No.608160030215)the Program for Innovative Research Team in Science and Technology in Fujian Province University(IRTSTFJ)
文摘The magnetically separable ternary polyetherimide/titanate@Fe3O4(PTF) photocatalysts of special heterostructure between magnetite(Fe3O4) microspheres and titanates nanosheets modified by polyetherimide(PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe3O4microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3 D microsphere and 2 D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe3O4microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe3O4microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe3O4microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5(96.7%) over 3 times reuse.
文摘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%BaTiO<sub>3</sub> (3 BZ), ZnO/18%BaTiO<sub>3</sub> (18 BZ), ZnO/ 33%BaTiO3 (33 BZ) and ZnO/48%BaTiO<sub>3</sub> (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 BaTiO<sub>3</sub> 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<sup>-1</sup> which decreased to 0.00532 min<sup>-1</sup> using 48 BZ, indicating the decrease of reaction rate for increasing the amount of BaTiO<sub>3</sub>. 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.
