Synthesis And Characteristics Of SnO₂ Nanomaterials Modified By Metalic Ion

As a kind of important n type semiconduct with a wide band-gap (3.6 eV), SnO2 nano material has attracted much attention due to their terrific opto-electrical and gas sensitive properties and their potential applications in luminescent, optical absorbent, catalytic, gas sensor, DMS,and Li-ion battery cathodes materials. Doping and calcining are the best methods to be used to improve the properties of nanomaterials and expand the application area. Therefore it is meaningful for material scientific research to study the synthesis and properties of SnO2 nanomaterials doped by metallic ion.In this dissertation, the influence of doping concentration and heat treatment temperature on the microstructure, optical and magnetic properties in the transitional-metal ions Fe, Co, Mn, rare earth ion Ce, and functional ion Zn-doped SnO2 nanoparticles synthesized by sol-gel-hydrothermal method have been investigated. Based on the above experiments, we have obtained research findings as follows:1.Fe-doped SnO2 nanoparticles were synthesized by sol-gel-calcination (marked SGC-series) and sol-gel-hydrothermal (marked SGH-series) routes respectively and the optical properties were investigated for the Fe-doped SnO2 nanoparticles for the first time. The two series of samples were characterized by XRD, BET, HRTEM, FTIR, PL, DRS, MPMS.Results show that the tetragonal rutile structured SnO2 crystallites have been obtained by the hydrothermal route without calcinations and the sol-gel-calcination route. The particle size decreased with the increase of doping concentration while increased with the increase of calcinging temperature. A red-shift was observed with the increase of Fe content and calcining temperatures. At the same time, there were an UV emission (389 nm) and a blue emission (470 nm) in all samples. Paramagnetism was observed in our samples.Compared with sol-gel-calcination route, sol-gel-hydrothermal route led to better dispersed spherical Fe-doped SnO2 nanopartilces with narrower sized distribution and larger specific surface area. So the hydrothermal method was used to prepare the samples for the following research in this dissertation.2.A simple hydrothermal method has been used for the synthesis of Co-doped SnO2 nanoparticles.The optical and magnetic characteristics of the samples have been investigated by means of absorption, photoluminescence spectra and the dependence of magnetization on the temperature or magnetic field. The results shows that the crystallite size of the SnO2 samples increased with the increase of calcining temperature while decreased with the increase of Co content. A red shift was observed in SnO2 with the increase of Co content and calcining temperatures. Magnetization measurements show paramagnetic behavior in our samples.3.Influences of Mn doping concentration and calcining temperatures on the microstructure, optical and magnetic properties were investigated deeply. With the increase of Mn content, the decreasing crystalline size of SnO2 and a noticeable red shift in the UV-VIS absorption were found. The intensity of PL peak in the sample decreased after being calcined. Mn doping in SnO2 did not result in ferromagnetism based on the magnetic measurements.4. Effects of Ce doping concentration and calcining temperatures on the microstructure, optical and magnetic properties were investigated in detail.With the increase of Ce content, the decreasing crystalline size of SnO2 and a noticeable blue shift in the UV-VIS absorption were found. An UV emission and a blue emission were observed in all samples and the position of peak did not change with the increase of Ce content and calcining temperature.5.Influences of Zn doping concentration and calcining temperatures on the microstructure, optical and magnetic properties were investigated in detail.Results showed that the tetragonal rutile structured SnO2 crystallites have been obtained by the hydrothermal method when the ratio of Zn:Sn was low. With the increase of Zn content, the decreasing crystalline size of SnO2 and a noticeable blue shift in the UV-VIS absorption were found. The intensity of UV emission decreased and that of blue emission increased with the increase of Zn content. Compared with the Zn-doped SnO2 nanoparticles as-prepared, the samples after calcined showed a redshift in both absorption edge and blue emission.The influences of synthesis, doping and calcining temperature on the microstructure and properties have become a major interdisciplinary research area in recent years. My research involves the microstructure and properties of SnO2 with different metal ion dopant calcined at different temperatures and synthesized by different methods.All these results are very important for summarizing the law of luminescence and absorption, exploring the magnetism, seeking methods for the synthesis of novel semiconductive nanomaterials, and designing the new luminescent materials. We believe that it is meaningful for both basic research and application research in the material field.