Preparation And Properties Of Spinel ZnAl₂O₄ Nanoparticles

With zinc aluminate spinel structure has high thermal stability,low mechanical resistance to heat,hydrophilic,surface acidity and uv barrier property of excellent performance,widely used in high temperature ceramic materials,catalysts,etc.Spinel（ZnAl₂O₄）nano materials because of its many excellent properties,causing great research interest.In this paper,pure ZnAl₂O₄,Cr doped and Cr/Mn co-doped ZnAl₂O₄ nanoparticles were prepared by hydrothermal method,and the effects of doping concentration on their micro structure,optical properties and photocatalytic properties were systematically studied.The main research contents are as follows:（1）ZnAl₂O₄ nanoparticles were successfully prepared by hydro thermal me thod,and the mic ro structure,morpho lo gy and optic al properties of ZnAl₂O₄ nanoparticles were characterized by means of XRD,SEM,FES EM and HRTEM,XEDS,UV-vis,FT-IR and PL.The microstructure study showed that the morphology of the sample was ellipsoidal granular structure,with particle、ize of about 24 nm,regular particle shape,uniform size and good dispersion.It is also found that ZnAl₂O₄ nanoparticles are single-phase spinel with high degree of crystallization and lattice distortion as lattice expansion.The optical properties of ZnAl₂O₄ nanocrystals showed that they had strong UV absorption capacity,and UV-vis spectra showed that the optical band gap of the samples decreased,which may be caused by the surface effect of the nanoparticles.（2）The doped Zn1-xCrxAl₂O₄（=0,0.01,0.03,0.05,0.07）nanoparticles were prepared by hydrothermal method using CTAB as surfactant,and the micro structure,shape of particles and optical properties of ZnAl₂O₄ nanoparticles were characterized by means of XRD,SEM,TEM and HRTEM,XEDS,UV-vis,XPS and PL.The results showed that the Cr single doped ZnAl₂O₄ nanoparticles were still spinel structure,and the morphology of the samples was uniform with good crystallinity and no agglomeration.With the increase of Cr3+ concentration,the band gap of the sample presented a decreasing trend.The analysis of CIE chromaticity diagram shows that the doping concentration will affect the luminescence color of the material,and the luminescence color can be adjusted by controlling the doping concentration.（3）The co-doped Zn_0.95-xCr_0.05Mn_x Al₂O₄（=0,0.of,0.03,0.05,0.07）nanocrystals were prepared by hydrothermal method,and the mic rostructure,optical and p hotocatalytic properties of the samp le s were characterized by means of XRD,SEM,TEM and HRTEM,XEDS,UV-vis,XPS and PL.The results show that the lattice of Zn0.95-xCr0.05MnxAl₂O₄ nanoparticles prepared by hydrothermal method will not change the structure of the sample and maintain the spinel structure,and the grain size will decrease.XPS results showed that most Cr and Mn io ns instead of Zn2+ entered the lattice of ZnAl₂O₄ without affecting the structure of ZnAl₂O₄.UV-vis spectral analysis showed that the co-doped Zn0.95-xCr0.05MnxAl₂O₄ sample had strong visible light absorption ability.The study on photocatalytic performance showed that the Cr/Mn co-doped Zn0.90Cr0.05Mn0.05 Al₂O₄ nanoparticles had the best photocatalytic performance and the fastest reaction rate.