The Preparation Of The Gas Sensing Material Nanometer In₂O₃ By The Method Of Microemulsion And The Study Of Its Phase Behavior

As a new gas sensing material, Indium oxide was demonstrated to have an unusual ability of sensitivity to such poison gas as CO, O3, NO2 and expected to conquer the problem of the traditional gas sensing materials. In the paper, The behavior of the microemulsion composed of the nonionic surfactant Triton X-100 is studied systematically in order to make the excellent gas sensor. The right microemulsion system of preparing the nano-sized In2O3 particles is sreened out, in which the particles are successfully synthesized.In the varaity methods of the nano-sized material preparation, microemulsion was adopted because of the simple equipment, easily controlled process and the mild reaction condition. However the emphasis of the present study is on the nano-sized material preparation, and the research of the preparation enviorment, the microemulsion system's screening is less and the systemic study of the synthesization system has not been seen yet.The ratio of laser permeance was the first time adopted to confirming the microemulsion phase invertion. Using the home-made 0.67um laser instrument, based on the sharp decreasing of laser permeation rate regularly near the transforming point, the microemulsion phase transformation is conformed. Compared to the traditioned confirmng method, the proposal one in the paper is more intuitionistic and exact than conductimetric and visual method.The various factors of influence on the region of the microemulsion, such as oil, cosurfactant, temperature and pH value, have been studied systemically. The appropriate microemulsion system to synthisize the nano-sized In2O3 has been screened out.The study showed that in the microemulsion composed of nonionicsurfactant TX-10, when the carbon chain length of oil plus that of the cosurfactant equals that of the nonpolar group of the surfactant, the system has the biggest area of the microemulsion region and highest water solubility which is appropriat to prepare the high quality nano-sized materials of even size distribution and different size gradation particles.The product of nano-sized In2O3 was analyzed based on the methods of TGA, DTA and IR, and the whole process of the reaction was discussed. The products, which were prepared under different conditions, were characterized by the TEM and X-ray diffraction. Based on the size and the morphology of the product to analyse the factors of the whole process, thereby, the optimal technology route and condition which were used to prepare the nano-sized In2O3 by the microemulsion method were determined.