Bismuth titanate （Bi4Ti3O12） platelets were prepared by molten salt method in a new salt system of CaCl2·NaCl at 650-750℃, using bismuth nitrate pentahydrate （Bi （NO3）3·H2O） and titanium butoxide （Ti...Bismuth titanate （Bi4Ti3O12） platelets were prepared by molten salt method in a new salt system of CaCl2·NaCl at 650-750℃, using bismuth nitrate pentahydrate （Bi （NO3）3·H2O） and titanium butoxide （Ti （OC4H9）4） as raw materials. The synthesis temperature of Bi4Ti3O12 platelets was decreased to 650℃ from 900-1100℃. The phase compositions and crystalline morphology of Bi4Ti3O12 platelets were investigated by XRD and SEM. The experimental results indicate that Bi4Ti3O12 platelets containing tetragonal and orthorhombic phase with the size of 1-3μm can be synthesized at 650℃ for 2 h, and the orthorhombic phase becomes the dominant phase at 750℃ for 5 h. The size and proportion of Bi4Ti3O12 platelets increase with the increment of the calcining temperature and holding time. The proportion of platelets increases to about ninety percent, and the platelets grow up to about 3-10μm at 750℃ for 5 h from 1-2μm at 650℃ for 2 h. This technical route provides a new low-temperature molten salt system for preparing platelets by molten salt methods.展开更多
Chemical solution route was used to synthesize Bi3.1La0.9Ti3O12 and CoFe2O4. Alternate CoFe2O4/Bi3.1La0.9Ti3O12 layers were deposited on Pt substrate （Pt/TiO2/SiO2/Si） by spin coating. X-ray diffraction and SEM （sc...Chemical solution route was used to synthesize Bi3.1La0.9Ti3O12 and CoFe2O4. Alternate CoFe2O4/Bi3.1La0.9Ti3O12 layers were deposited on Pt substrate （Pt/TiO2/SiO2/Si） by spin coating. X-ray diffraction and SEM （scanning electron microscopy） studies show composite-like polycrystalline films. Films were studied for leakage current, dielectric response, ferroelectric and ferromagnetic properties. Leakage current was low （〈 10^-8 A） in electric field below 120 kV/cm, and the dielectric response shows relaxation. Dielectric loss （tan 8） reduces 〈 3% at 10^6 Hz. Two and four layer structures showed room temperature FE （ferroelectric） and FM （ferromagnetic） responses with FE Pr （polarization） 〉 25℃/cm2 and ferromagnetic Mr （memory） 〉 52 emu/cm3. Co-existence of FE and FM can be attributed to stress due to different crystal structures of the material involved in composite film structure.展开更多
TiO2/Bi4 Ti3 O12 hybrids have been widely prepared as promising photocatalysts for decomposing organic contaminations.However,the insufficient visible light absorption and low charge separation efficiency lead to thei...TiO2/Bi4 Ti3 O12 hybrids have been widely prepared as promising photocatalysts for decomposing organic contaminations.However,the insufficient visible light absorption and low charge separation efficiency lead to their poor photocatalytic activity.Herein,a robust methodology to construct novel TiO2/Bi4 Ti3 O12/MoS2 core/shell structures as visible light photocatalysts is presented.Homogeneous bismuth oxyiodide(BiOI) nanoplates were immobilized on electrospun TiO2 nanofiber surface by successive ionic layer adsorption and reaction(SILAR) method.TiO2/Bi4 Ti3 O12 core/shell nanofibers were conveniently prepared by partial conversion of TiO2 to high crystallized Bi4 Ti3 O12 shells through a solid-state reaction with BiOI nanoplates,which is accompanied with certain transition of TiO2 from anatase to rutile phase.Afterwards,MoS2 nanosheets with several layers thick were uniform decorated on the TiO2/Bi4 TiO3 O12 fiber surface resulting in TiO2/Bi4 Ti3 O12/MoS2 structures.Significant enhancement of visible light absorption and photo-generated charge separation of TiO2/Bi4 Ti3 O12 were achieved by introduction of MoS2.As a result,the optimized TiO2/Bi4 Ti3 O12/MoS2-2 presents 60% improvement for photodegrading RhB after 120 min irradiation under visible light and 3 times higher of apparent reaction rate constant in compared with the TiO2/Bi4 Ti3 O12.This synthetic method can also be used to establish other photocatalysts simply at low cost,therefore,is suitable for practical applications.展开更多
Bi2WTi3O12 ceramics are fabricated by the conventional solid-state reaction process. With increasing temperature the sample first has metallic behavior, then strong electrical fluctuations above 100℃, and finally exh...Bi2WTi3O12 ceramics are fabricated by the conventional solid-state reaction process. With increasing temperature the sample first has metallic behavior, then strong electrical fluctuations above 100℃, and finally exhib-its stable nonlinear properties characterized by semiconduc-tivity above 300℃ at low field (E ≤ 100 V/mm). The Ar-rhenius law for electrical conductivity by thermal activation is not suitable to explain the anomalous results. XRD analysis reveals that Bi2WO6 is the main phase and Bi4Ti3O12 is the second phase. Based on the phase transition of tungsten tri-oxide from room temperature to about 300℃, the electrical properties of Bi2WTi3O12 ceramics can be explained.展开更多
文摘Bismuth titanate （Bi4Ti3O12） platelets were prepared by molten salt method in a new salt system of CaCl2·NaCl at 650-750℃, using bismuth nitrate pentahydrate （Bi （NO3）3·H2O） and titanium butoxide （Ti （OC4H9）4） as raw materials. The synthesis temperature of Bi4Ti3O12 platelets was decreased to 650℃ from 900-1100℃. The phase compositions and crystalline morphology of Bi4Ti3O12 platelets were investigated by XRD and SEM. The experimental results indicate that Bi4Ti3O12 platelets containing tetragonal and orthorhombic phase with the size of 1-3μm can be synthesized at 650℃ for 2 h, and the orthorhombic phase becomes the dominant phase at 750℃ for 5 h. The size and proportion of Bi4Ti3O12 platelets increase with the increment of the calcining temperature and holding time. The proportion of platelets increases to about ninety percent, and the platelets grow up to about 3-10μm at 750℃ for 5 h from 1-2μm at 650℃ for 2 h. This technical route provides a new low-temperature molten salt system for preparing platelets by molten salt methods.
文摘Chemical solution route was used to synthesize Bi3.1La0.9Ti3O12 and CoFe2O4. Alternate CoFe2O4/Bi3.1La0.9Ti3O12 layers were deposited on Pt substrate （Pt/TiO2/SiO2/Si） by spin coating. X-ray diffraction and SEM （scanning electron microscopy） studies show composite-like polycrystalline films. Films were studied for leakage current, dielectric response, ferroelectric and ferromagnetic properties. Leakage current was low （〈 10^-8 A） in electric field below 120 kV/cm, and the dielectric response shows relaxation. Dielectric loss （tan 8） reduces 〈 3% at 10^6 Hz. Two and four layer structures showed room temperature FE （ferroelectric） and FM （ferromagnetic） responses with FE Pr （polarization） 〉 25℃/cm2 and ferromagnetic Mr （memory） 〉 52 emu/cm3. Co-existence of FE and FM can be attributed to stress due to different crystal structures of the material involved in composite film structure.
基金supported financially by the National Natural Science Foundation of China(Nos.21501140,21403165,51372197)the Outstanding Youth Science Fund of Xi’an University of Science and Technology(No.2019YQ2-06)the Key Innovation Team of Shaanxi Province(No.2014KCT-04)。
文摘TiO2/Bi4 Ti3 O12 hybrids have been widely prepared as promising photocatalysts for decomposing organic contaminations.However,the insufficient visible light absorption and low charge separation efficiency lead to their poor photocatalytic activity.Herein,a robust methodology to construct novel TiO2/Bi4 Ti3 O12/MoS2 core/shell structures as visible light photocatalysts is presented.Homogeneous bismuth oxyiodide(BiOI) nanoplates were immobilized on electrospun TiO2 nanofiber surface by successive ionic layer adsorption and reaction(SILAR) method.TiO2/Bi4 Ti3 O12 core/shell nanofibers were conveniently prepared by partial conversion of TiO2 to high crystallized Bi4 Ti3 O12 shells through a solid-state reaction with BiOI nanoplates,which is accompanied with certain transition of TiO2 from anatase to rutile phase.Afterwards,MoS2 nanosheets with several layers thick were uniform decorated on the TiO2/Bi4 TiO3 O12 fiber surface resulting in TiO2/Bi4 Ti3 O12/MoS2 structures.Significant enhancement of visible light absorption and photo-generated charge separation of TiO2/Bi4 Ti3 O12 were achieved by introduction of MoS2.As a result,the optimized TiO2/Bi4 Ti3 O12/MoS2-2 presents 60% improvement for photodegrading RhB after 120 min irradiation under visible light and 3 times higher of apparent reaction rate constant in compared with the TiO2/Bi4 Ti3 O12.This synthetic method can also be used to establish other photocatalysts simply at low cost,therefore,is suitable for practical applications.
文摘Bi2WTi3O12 ceramics are fabricated by the conventional solid-state reaction process. With increasing temperature the sample first has metallic behavior, then strong electrical fluctuations above 100℃, and finally exhib-its stable nonlinear properties characterized by semiconduc-tivity above 300℃ at low field (E ≤ 100 V/mm). The Ar-rhenius law for electrical conductivity by thermal activation is not suitable to explain the anomalous results. XRD analysis reveals that Bi2WO6 is the main phase and Bi4Ti3O12 is the second phase. Based on the phase transition of tungsten tri-oxide from room temperature to about 300℃, the electrical properties of Bi2WTi3O12 ceramics can be explained.
