Study On The Regulation, Synthesis And Performance Of Lead-free Piezoelectric Smart Composites Based On Barium Titanat

With the rapid development of the global economy,the market demand for textile industry,food processing industry,printing,dye and pharmaceutical industry is increasing day by day.However,the pollutants discharged to rivers by these industries are particularly serious damage to the environment,especially affecting the human living water and living environment,so the protection of the environment is particularly significant.In all water pollution,the water pollution caused by the discharge of various organic pollutants is an urgent problem to be solved due to the high retardation of pollutants to sunlight,and strong resistance to microbial digestion and temperature.Photocatalytic technology is regarded as an efficient and green technology to degrade dye and drug in wastewater due to its advantages of low cost,green pollution,and so on.Photocatalyst plays an important role in the efficient degradation of pollutants.Perovskite-type BaTiO₃semiconductor material is a common photocatalyst,which is often used in the treatment of water pollution due to its advantages of high photocarrier mobility,environmental friendliness and high photocatalytic activity.In this thesis,we proposed the use of polyacrylamide gel method combined with low temperature sintering technology to construct the BaTiO₃/TiO₂,BaTiO₃/CeO₂,BaTiO₃/Al₂O₃heterojunction photocatalysts and BaTiO₃/TiO₂/CeO₂phosphors.The samples were characterized by X-ray diffractometer,Fourier transform infrared spectrophotometer,X-ray photoelectron spectrometer,ultraviolet visible spectrophotometer,scanning electron microscope and transmission electron microscope.The photocatalytic mechanism and photoluminescence mechanism were described in detail by experiments on the photocatalytic and photoluminescence properties of the samples.Specific research work is as follows:（1）The pure BaTiO₃was synthesized by the polyacrylamide gel route with using tetrabutyl titanate as titanium source and adding Na OH into the precursor solution.The effects of titanium source,acid,base and sintering temperature on the purity of BaTiO₃phase were systematically studied.Various characterization confirmed that the pure BaTiO₃could be obtained by the polyacrylamide gel method with Na OH in precursor solution and tetrabutyl titanate as titanium source and the sintering temperature of 950°C.Methylene blue was used as the target pollutant for piezoelectric and photocatalytic experiments.The experiments confirmed that the optimum catalyst content and dye concentration for the degradation of methylene blue by BaTiO₃photocatalyst were 1.5 g/L and 10 mg/L,respectively.Combined with the results of catalytic experiment and capture experiment,the synergistic mechanism of piezoelectricity and photocatalysis was proposed.（2）The BaTiO₃/TiO₂,BaTiO₃/CeO₂,BaTiO₃/Al₂O₃heterojunction photocatalysts were constructed by the polyacrylamide gel method combined with low temperature sintering technology.The optimum composite ratio was determined by photocatalytic degradation of tetrabromobisphenol A,tetracycline hydrochloride and tetracycline hydrochloride,respectively.Experiments indicate that the photocatalytic activities of BaTiO₃/（10 wt%）TiO₂,BaTiO₃/（20 wt%）CeO₂,BaTiO₃/（5wt%）Al₂O₃are significantly higher than that of other proportional photocatalysts,and also the photocatalytic mechanism is systematically analyzed.（3）The BaTiO₃/TiO₂/CeO₂phosphor was constructed by the introduction CeO₂into BaTiO₃/（10 wt%）TiO₂matrix,and the photoluminescence properties of BaTiO₃/TiO₂/CeO₂phosphors were explored by the fluorescence spectrophotometer.The optical properties of BaTiO₃/TiO₂/CeO₂phosphors show that the optical response range of single components BaTiO₃,CeO₂and TiO₂is expanded to 500 nm.The BaTiO₃/TiO₂/CeO₂phosphor showed strong emission peaks at 430 and 472 nm with the excitation wavelength of 310 nm.Therefore,the BaTiO₃/TiO₂/CeO₂phosphor has a potential application prospect in the blue emission field.