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Preparation and Structural Analysis of Magnesium Oxide Aerogels Jiankai Zhang1, Xiaohong Chen1, Ran Liu1, Huaihe Song1, Zhihong Li 2 (1.State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China） (2. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China) ABSTRACT Magnesium oxide aerogels were made by sol-gel process using magnesium methoxide as precursor, methanol and deionized water as solvent with ethanol supercritical fluid drying. The influences of the different factors on the gel time and the specific surface area of magnesium oxide aerogels were studied, and the structure and morphology were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and X-ray diffraction (XRD), and the Small Angle X-ray Scatter (SAXS) was utilized to determine the fractural structure of the magnesium oxide aerogels. The results show that MgO aerogels belong to the typical mesoporous materials with rich network and highly developed pore structure, and the specific surface area is 904.9 m2/g, the apparent density is 0.055 g/cm3, the average pore size is 19.6 nm. The results of SAXS analysis show that the fractal dimension of the MgO aerogels is 2.32 in high q area which proves the existence of rough surface and pore fractal structure. INTRODUCTION With numerous inherent excellent properties, like high porosity, high specific surface area, low thermal conductivity, low density 1-4 and obvious fractal structure 5-8, aerogels are applied in aerospace9, energy10, environmental protection11, catalysis12, etc. Moreover, further researches about the aerogel materials have expanded their products to Al2O313、CuO14、ZnO15、Fe2O316、 ZrO217、MnO218 aerogels and multicomponent composite aerogels19-25. However, study on preparation and structural analysis by SAXS of magnesium oxide aerogels is very rare as yet. Magnesium Oxide has many characteristics, such as non-toxic, antibacterial, catalysis, inflaming retarding etc. Therefore, it has been mainly used for catalytic reaction of dehydrogenation of methanol and formic acid or the formation of oxygen free radicals and denitrating organic catalytic 26-28.Other applications include the use of it as a buffer material in ferroelectric materials, as humidity sensors, and as the secondary emission material in plasma display panels29-31. To increase the surface area and create a three-dimensional net structure of the Magnesium Oxide , which is a typical basic oxide, MgO aerogels were synthesized by sol-gel process and supercritical drying. At present, there have been some researches in this field. Winny Dong et al.32found that acetic acid and glycerol work respectively well in initiating the formation of Mg-O, Mg-OH, Mg-H bonds and slowing the gelation rate of the wet gel. Andrea Feinle et al. 33showed the different roles between ionic and non-ionic surfactants in controlling the particle growth during sol-gel step and that the surfactant and acid can adjust the morphology of the