Cubic (Zn,Li)TiO3 powders were synthesized through a modified sol-gel route including the Pechini process via a three-step heat treatment.The as-synthesized (Zn,Li)TiO3 could be stable up to 1000 °C.The diele...Cubic (Zn,Li)TiO3 powders were synthesized through a modified sol-gel route including the Pechini process via a three-step heat treatment.The as-synthesized (Zn,Li)TiO3 could be stable up to 1000 °C.The dielectric constant and dielectric loss tangent of all the synthesized (Zn,Li)TiO3 samples at different measurement frequencies showed the similar tendency.At the same frequency,the dielectric constant and the dielectric loss tangent of (Zn,Li)TiO3 samples decreased and increased,respectively,with the lithium doping content increase.The as-prepared (Zn,Li)TiO3 showed improved microwave dielectric properties,and its maximum value of quality factor could reach 34000 GHz.展开更多
The direct activation of methane under mild condition to achieve highly selective of oxygenates is a challenging project.In this study,a well dispersed silver supported ZnTiO_(3) catalyst was prepared to achieve selec...The direct activation of methane under mild condition to achieve highly selective of oxygenates is a challenging project.In this study,a well dispersed silver supported ZnTiO_(3) catalyst was prepared to achieve selective preparation of methanol from methane and water under mild condition.X-ray diffraction,transmission electron microscopy and X-ray photoelectron spectroscopy characterizations demonstrate that silver species are uniformly dispersed on ZnTiO_(3) surface in the form of metallic silver nanoparticles.The photoelectric characterizations reveal that the addition of silver species enhances light absorption and promotes charge separation of the catalysts.Under the reaction conditions of 50℃and 3 MPa,the methanol is obtained as the only liquid product over the designed Ag/ZnTiO_(3) catalyst under light irradiation.In this photocatalytic process,the holes generated by ZnTiO_(3) activate water to produce intermediate·OH,which further reacts with methane to synthesize methanol.The silver species as co-catalysts extend the light absorption range of ZnTiO_(3) as well as promote charge separation.展开更多
The local structure of an alternative Pb(Zn1/3Nb2/3)O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb(Zn1/3Nb2/3)O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaT...The local structure of an alternative Pb(Zn1/3Nb2/3)O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb(Zn1/3Nb2/3)O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaTiO33 perovskite phase stabilizer. Then, x-ray absorption spectroscopy and density functional theory are employed to calculate the local structure configuration and formation energy of the prepared samples. Ba2+ is found to replace Pb2+ in AA-site with Zn2+ occupying BB-site in Pb(Zn1/3Nb2/3)O3, while in the neighboring structure, Ti4+4+ replaces Nb5+5+ in BB-site with Pb2+2+ occupying AA-site. With the substitution of BaTiO33 in Pb(Zn1/3Nb2/3)O3, the bond length between Zn2+ and Pb2+ is longer than that of the typical perovskite phase of Pb(Zn1/3Nb2/3)O3. This indicates the key role of BaTiO33 in decreasing the steric hindrance of Pb2+ lone pair, and the mutual interactions between Pb2+ lone pair and Zn2+ and the formation energy is seen to decrease. This finding of the formation energy and local structure configuration relationship can further extend a fundamental understanding of the role of BaTiO33 in stabilizing the perovskite phase in PbZn13Nb23O3-based materials, which in turn will lead to an improved preparation technique for desired electrical properties.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
SrTiO_(3)/ZnTiO_(3)heterolayered thin films were fabricated by spin coating Sr-Ti and Zn-Ti sol-gel precursors on fused silica substrate.The SrTiO_(3)and ZnTiO_(3)were coated alternatively to form ABAB heterolayered t...SrTiO_(3)/ZnTiO_(3)heterolayered thin films were fabricated by spin coating Sr-Ti and Zn-Ti sol-gel precursors on fused silica substrate.The SrTiO_(3)and ZnTiO_(3)were coated alternatively to form ABAB heterolayered thin films.The thickness of individual layers was tailored by controlling the coating layers.The structure characterization of the thin films showed independent structure of each layer while the microwave dielectric properties and optical band gaps can be tuned by changing the layer configuration.The effects of the layer configuration on the dielectric and optical properties were studied.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.20731001,20871015 and 50725415)the Program for New Century Excellent Talents in University,China(NCET)+1 种基金the National Basic Research Program of China(No.2007CB613601)the Program for Changjiang Scholars and Innovative Research Team in University,China(No.IRT0708)
文摘Cubic (Zn,Li)TiO3 powders were synthesized through a modified sol-gel route including the Pechini process via a three-step heat treatment.The as-synthesized (Zn,Li)TiO3 could be stable up to 1000 °C.The dielectric constant and dielectric loss tangent of all the synthesized (Zn,Li)TiO3 samples at different measurement frequencies showed the similar tendency.At the same frequency,the dielectric constant and the dielectric loss tangent of (Zn,Li)TiO3 samples decreased and increased,respectively,with the lithium doping content increase.The as-prepared (Zn,Li)TiO3 showed improved microwave dielectric properties,and its maximum value of quality factor could reach 34000 GHz.
基金Project supported by the National Key Technologies R&D Program of China(2022YFE0114800)National Natural Science Foundation of China(22172032,U22A20431)。
文摘The direct activation of methane under mild condition to achieve highly selective of oxygenates is a challenging project.In this study,a well dispersed silver supported ZnTiO_(3) catalyst was prepared to achieve selective preparation of methanol from methane and water under mild condition.X-ray diffraction,transmission electron microscopy and X-ray photoelectron spectroscopy characterizations demonstrate that silver species are uniformly dispersed on ZnTiO_(3) surface in the form of metallic silver nanoparticles.The photoelectric characterizations reveal that the addition of silver species enhances light absorption and promotes charge separation of the catalysts.Under the reaction conditions of 50℃and 3 MPa,the methanol is obtained as the only liquid product over the designed Ag/ZnTiO_(3) catalyst under light irradiation.In this photocatalytic process,the holes generated by ZnTiO_(3) activate water to produce intermediate·OH,which further reacts with methane to synthesize methanol.The silver species as co-catalysts extend the light absorption range of ZnTiO_(3) as well as promote charge separation.
基金Supported by the Thailand Research Fund under Grant No TRG5880097
文摘The local structure of an alternative Pb(Zn1/3Nb2/3)O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb(Zn1/3Nb2/3)O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaTiO33 perovskite phase stabilizer. Then, x-ray absorption spectroscopy and density functional theory are employed to calculate the local structure configuration and formation energy of the prepared samples. Ba2+ is found to replace Pb2+ in AA-site with Zn2+ occupying BB-site in Pb(Zn1/3Nb2/3)O3, while in the neighboring structure, Ti4+4+ replaces Nb5+5+ in BB-site with Pb2+2+ occupying AA-site. With the substitution of BaTiO33 in Pb(Zn1/3Nb2/3)O3, the bond length between Zn2+ and Pb2+ is longer than that of the typical perovskite phase of Pb(Zn1/3Nb2/3)O3. This indicates the key role of BaTiO33 in decreasing the steric hindrance of Pb2+ lone pair, and the mutual interactions between Pb2+ lone pair and Zn2+ and the formation energy is seen to decrease. This finding of the formation energy and local structure configuration relationship can further extend a fundamental understanding of the role of BaTiO33 in stabilizing the perovskite phase in PbZn13Nb23O3-based materials, which in turn will lead to an improved preparation technique for desired electrical properties.
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.
文摘SrTiO_(3)/ZnTiO_(3)heterolayered thin films were fabricated by spin coating Sr-Ti and Zn-Ti sol-gel precursors on fused silica substrate.The SrTiO_(3)and ZnTiO_(3)were coated alternatively to form ABAB heterolayered thin films.The thickness of individual layers was tailored by controlling the coating layers.The structure characterization of the thin films showed independent structure of each layer while the microwave dielectric properties and optical band gaps can be tuned by changing the layer configuration.The effects of the layer configuration on the dielectric and optical properties were studied.