Hydrothermal Synthesis And Photocatalytic Property Study Of A₂B₂O₇ Composite Oxides

The compounds with the general formula of A₂B₂O₇ include many kinds of composite oxides with different structure. Because they possess many excellent physical properties,they have become the important investigation object in the nanomaterials field. At the same time;they were the important application materials in actual life. However,these compounds were generally synthesized through the traditional high temperature solid state reaction,which is not only wasting energy,polluting environment,but is easily induce impurity and the particle size is large.The main points of this thesis rest with exploring novel hydrothermal methods to synthesize functional composite oxides nanomaterials , and studying the photocatalytic properity of the products,and investigating the effect of particle size,mopholougy and the structure on the propertiy. The main results achieved are summed up as following:1. A hydrothermal process had been designed and successly applied in the synthesis of many composite oxides nanomaterials with the general formula of A₂B₂O₇ (A=Y,La,Bi;B=Sn,Ti).2. Nanosized Y₂Sn₂O₇ powder photocatalysts with different particle sizes were synthesized through the low temperature hydrothermal method by using different organic agents (polymethyl methacrylate: PMMA , cetyltrimethyl ammonium bromide: CTAB or ethylene diamine tetraacetic acid: EDTA). A formation mechanism of the Y₂Sn₂O₇ nanoparticles with different sizes in the presence of organic agents was proposed. The diffuse reflection spectrum shows that with the decrease of sample particle size,the absorbance edges of samples move to long wavelength,that is to say,the red shift occurs. The surface areas of samples indicate that different kinds of organic agents result in the difference in the particle sizes,and the surface areas of the samples. The surface areas varied with the heat treatment temperature. The photo catalytic experiments showed that the...