Preparation Of SnO 2 - Sub - Nanowire Clusters And Their Infrared Emission Properties

This paper adopts a method combined the theoretical and experimental research, to explore the low infrared emission mechanism and the law of semiconductor coatings of SnO2by means of its conductive properties, the relationship between particle scattering properties and the infrared emissivity.In theoretical research, first of all, the relationship among the infrared emissivity, conductivity and scattering coefficient were analyzed theoretically based on the semiconductor theory and the electromagnetic wave transmission theory in coatings. The results show that the infrared emissivity decreased with the increase of conductivity and scattering coefficient. Based on the first principle of density functional theory (DFT), the electronic structures of intrinsic bulk SnO2super cell, SnO2oxygen vacancy super cell, Sb doped SnO2super cell, intrinsic SnO2nanowires super cell and Sb doped SnO2nanowires super cell were simulated and calculated. Comparing the relationship between the conductivity, electronic structure and the infrared reflectivity in the intrinsic, oxygen vacancy and Sb doped bulk SnO2and the nanowires materials. The results show that the conductivity and the infrared reflectivity of the SnO2oxygen vacancy super cell is the highest in the bulks; The parameters of Sb doped SnO2nanowires is better than that of the bulks; The parameters of Sb doped SnO2nanowires increases with Sb doping concentration increases after the first decreases, and the doping concentration was4%, reached the peak. All of these will provide a theoretical guidance for the further design and preparation of high performance low infrared emissivity materials.In the experiment, using SnCl4·5H2O as the source material, and NaOH as themineralizer, flower-like SnO2nanowire cluster were prepared by hydrothermal method, and based on the orthogonal design theory to optimize the technological parameters of preparation of flower-like SnO2nanowire clusters. The composition of samples, microstructure, morphology, infrared emission rate were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and infrared emissivity measuring instrument and so on.The results show that:the prepared productsare rutile SnO2, alkali salt ratio ([OH-]/[Sn4+]) provides theenvironmental driving force for the growth of different morphologies of particles; emission rate of flower-like products decreased with increasing of aspect ratio, the lowest infraredemission rate is0.825. By analyzing the results of the products characterization, we explained the mechanism oflow infrared emissivity of the flower-like SnO2nanowire clusters, as well as the growth mechanism of different morphologies of SnO2particles.Flower-like SnO2nanowire clusters were prepared by the surface-active agents polyacrylamide (PAM) assisted hydrothermal method,and the microstructure and infrared emission performanceof the samples were characterized. The results show that PAM effectively increases theaspect ratio of the flower-like SnO2nanowire clusters and saturation of the flower bud, thus increased scattering interface of the products to the infrared electromagnetic wave, and then improve the infraredemissivity. When [PAM]/[Sn4+]=0.0001%, the product was homogeneous, well dispersed flower-like products, the aspect ratio of the products is12.67, and the minimμm emission rate reached0.682.Based on the optimized technological parameters, Sb doped SnO2nanomaterial which used SbO2as dopant was preparaed. Then, analysis about the influence of Sb doping concentration and post heat treatment temperature on the infrared emitting rate were carried out. The results show that although Sb inhibited the growth and development of nanowire clusters, but effectively improved the electric conductivity of the product, so as to effectively reduced the infrared emitting rate.When the Sb doping concentration was7%,and the heat treatment temperature is1100℃, the doping product lowest infrared emitting rate is0.521. This article analyzed the control mechanism of the infrared emitting rate from the microscopic.Combined with the theoretical and experimental research, can draw the conclusion:in this article research realm, after heat treatment at1100℃, theanthoid ATO located in harmonic oscillation area and it’s particles in thesize of infrared wavelength presents good low infrared emitting rate. Therefore, it may become a substitute for ITO and become a hot spot in the research field of semiconductor filler materials.