【作者】 朱协彬；

【导师】 段学臣；

【作者基本信息】 中南大学 ， 材料物理与化学， 2007， 博士

【摘要】 铟锡氧化物（Indium Tin Oxide，ITO）是一种重要的铟材料，约占铟产品总量的60％以上，是一种高度简并的N型半导体，因其具有优异的光电性能，而在电子工业、汽车工业、建筑工业、太阳能利用，宇航和军事、发光材料和器件领域、微波屏蔽和激光辐射防护等方面，具有极其广泛的应用。本课题是依托国家863高技术研究发展计划项目《多功能纳米复合氧化物导电浆料的制备与开发》（2002AA302606）而开展的研究工作，采用软化学法研制ITO粉体和湿法镀膜用浆料，以及ITO介孔组装体系。这一研究对于开发新型ITO纳米复合材料，以及开拓其新的应用领域，具有重要的意义。本课题的研究采用软化学法中的前驱体热解法制备ITO粉体。首先考察了pH值与反应溶液中金属离子浓度的关系，利用双滴加方式，获得合适的ITO前驱体；然后通过热重分析研究了ITO前驱体的热解过程，考察煅烧温度对ITO晶型结构的影响，选择合适温度，前驱体经煅烧分解，得到不同表面形状的ITO粉体。结果发现：当滴加5％氨水时，得到的ITO粉体为￠20nm～￠30nm的类球形，而当选择滴加25％氨水时，得到的ITO粉体为径长比约￠20nm～￠30nm x140nm～300nm的棒形。通过实验，获得的最佳反应条件为：溶液[In³⁺]浓度为0.10M，掺锡比为9：1，加入分散剂为MC，反应溶液pH值为7～8，反应温度70℃，ITO前驱体锻烧温度为700℃，保温2h，获得ITO粉体晶粒粒径为21.6nm，单分散性，粒度均一，电阻率为1.92×10^-3Ω·mm，导电性能较好，ITO粉体结晶完善，具有立方铁锰矿晶形结构。为了改善纳米ITO粉体的晶体结构，晶径分布及其分散性，重点研究了添加不同分散剂对纳米ITO粉体的影响。加入非离子型表面活性剂的PP和PG，有较好的分散性，但对ITO晶粒粒径都没有影响，PG对ITO结晶强度有增强作用；当加入高分子化合物的MC时，能减小ITO晶粒粒径。利用LaMer理论的成核和生长机理，分析了分散剂对纳米ITO粉体的作用。并通过研究不同反应条件对纳米ITO粉体的表面形状、晶体结构、晶粒粒径和导电性能的影响，探讨了ITO的半导化和导电机理。用软化学法制备的纳米ITO粉体为制备ITO浆料作好了准备。以纳米ITO粉体为原料，采用球磨-超声空化分散法制备了无水乙醇相ITO浆料和水相ITO浆料，重点研究了在球磨分散时间和分散剂对浆料稳定性的影响。对无水乙醇相浆料进行沉降分析研究发现，在球磨分散时间24h，TC和BA分散剂最佳含量（γ）为5％，而PP分散剂γ值为5～10％之间时，分散效果最好。分散剂PP、TC和BA在γ值为5％时，球磨分散时间48h效果最佳，并借助超声空化作用，在15d内，能使浆料沉降高度与浆料总高度的比值（Ratio Sediment Height，RSH）维持在10％以内。在24h～96h球磨分散时间内，ITO浆料稳定性由强转弱的顺序为PP＞BA＞TC。对水相ITO浆料沉降分析研究发现，随着分散剂MC用量、ITO粉体用量和球磨分散时间的增加，ITO浆料稳定性增强。在MC的γ值为15％，球磨分散时间为48h时，借助超声空化，水相ITO浆料稳定性最好，此时在120d的RSH在1.8％以内。利用DLVO稳定理论和空间位阻稳定理论进行分析，发现分散剂PP对ITO浆料的分散机制为空间位阻稳定作用，TC和BA对ITO浆料的分散机制为静电稳定作用，MC对ITO浆料的分散机制为静电和空间位阻稳定作用。利用匀胶涂膜方法，将无水乙醇相ITO浆料在玻璃上涂膜，得到的ITO薄膜平整，方块电阻196Ω／□，可见光透射率≥87.8％，红外光反射率为70％左右。以浆料的制备为基础，在软化学法中的溶胶．凝胶法基础上，采用浸泡-加热分解法制备了IO／SiO₂和ITO／SiO₂纳米介孔组装体，发现后者比前者具有较强的光致发光性能，即在激发波长275nm，发射波长360nm处具有荧光增强效应，光谱峰值为504。而在软化学法中的溶胶-凝胶法基础上，采用混合凝胶-干燥法制备了SiO₂气凝胶和ITO／SiO₂气凝胶，发现后者也比前者具有较强的光致发光性能，即在激发波长220nm，发射波长398nm处，具有荧光增强效应，光谱峰值为1647，且PL谱发生了右偏移，偏移量为15nm。气凝胶ITO／SiO₂较介孔组装体ITO／SiO₂有更强的光致发光性能。论文中评述了ITO纳米材料制备、性能和应用方面的国内外研究状况；分析了ITO纳米材料制备原理、分散稳定理论和半导化机理；用前驱体热解法制备了纳米ITO粉体，球磨．超声空化分散法制备了ITO浆料，用混合凝胶．干燥法和浸泡．热分解法制备了ITO／SiO₂介孔复合材料，在制备工艺、形成机制、物理性能和影响因素方面进行了有益探索，为ITO隔热或发光材料，以及新型ITO功能性复合材料等产品的研发和应用打下了基础。更多还原

【Abstract】 ITO （Indium Tin Oxide） is a category of important material bearing indium, which accounts for over 60% of the total indium product yield. ITO is a highly simplified N-type semiconductor. Because of its excellent photoelectric performance, it is extensively used in the fields such as electric industry, automobiles, construction industry, solar energy, space navigation and military affairs, luminescent materials and devices, as well as microwave shield and laser radioprotection. The present work on preparation of ITO powder and suspension for the application of coating with wet method and on the synthesise of ITO mesoporous assembly system, is supported by the National High Tech Research and Development Program of China （863 Program） under Grant No. 2002AA302606, namely, "Preparation and Development of Multi-Functional Nanometer Size Oxide Composite Suspension with Electric Conductivity". The work done here are very important to develop new type nanocomposite materials of ITO for their application in new fields.ITO powder was prepared by precursor-pyrolysis method, one of chemie douce, in this dissertation. The relations between pH value and the metallic ion concentration in the reaction solution were studied to prepare a suitable ITO precursor with "two-drop" method at first. And the process of ITO precursor-pyrolysis was then investigated via through thermogravimetric analysis. ITO powder with different surface shapes were gained through the pyrolysis of ITO precursor at the suitable calcinations temperature depending on the effects on the crystal structure of ITO powder. The results show that the clubbed nanometer ITO powder has been prepared when choosing the 25% ammonia solution to add dropwise, with the ratio of diameter to length￠of 30nm～40nm x 140nm～300nm, while the near-spherical nanometer ITO powder has been prepared when choosing the 5% ammonia solution to add dropwise with the diameter of￠of 20nm～30nm, under the other same conditions. The optimal reaction conditions for synthesis of ITO powder with the cubic iron manganese ore crystal structure, perfect crystallization, monodispersity, uniform size, good electrical conductivity, as well as the resistance ratio of 1.92×10^-3Ω·mm are: the added dispersant is MC, the reaction temperature is 70℃, the concentration of [In³⁺] in the reaction solution is 0.10M, and the ratio of Sn-doped is 9:1, and the pH value is 7～8 in the reaction solution, the temperature of heat treatment is 700℃and the time of heat treatment is 2h.To improve the crystal structure, distribution of crystallite size and dispersion of ITO powder, the effects of dispersants added in the reaction of preparing ITO precursor on the properties of ITO powder was discussed. No effects on ITO crystallite size are found when non-ion surfactant PP and PG were added, but the enhanced effect on the crystal intensity of ITO powder when PG was added. Moreover, PP and PG are helpful for dispersity of ITO powder. However ITO crystallite size is reduced when polymer MC is added. The effects of the influence factors on the surface shape, crystal structure, crystallite size and electrical conductivity of the prepared nanometer ITO powder was discussed with the nucleation and growth mechanism of LaMer theory and semi-conductivity and electrical conductivity mechanism of ITO. ITO nanopowder prepared by chemic douce is ready for the preparing ITO suspension.The stabilized ITO ethanol absolute suspension and ITO aqueous suspension were prepared by ball milling and ultrasonic cavitations dispersion method through dispersing ITO powder into ethanol absolute and distilled water separately, and the effects of ball milling time and dispersants on the stabilization of ITO suspension were studied. The results showed that under ball mill dispersing period of 24h, TC and BA optimalΥvalue of such dispersing agents is 5% separately, while for the dispersing agent PP, itsΥvalue is between 5% and 10%, its dispersible effect is better than that of the first two dispersing agents. It is also discovered that, when the dispersing agent relative ITO powder quality fraction is 5%, ball mill dispersing time of 48h is the optimal ball milling dispersion time, and within 15d, PP, TC and BA can enable the RSH to maintain within 10%. In the ball milling dispersion time period between 24h and 96h, the descending order of ITO suspension stability is PP＞BA＞TC. It is seen that through the research on the stability of suspension in aqueous phase, dispersing agent MC has good dispersing effects in the ITO suspension process during the ball milling. When the MC amount used accounts for relative ITO powder quality fraction is constant, with MC amount used , ITO powder amount used and ball milling dispersion time increase, ITO suspension stability enhances; When the MC amount used is 15%, the ball milling dispersion time is 48h, the ITO suspension stability becomes best, and its RSH is within 1.8% during 120d.Based on DL VO stabilization theory and space steric hindrance theory, the functional mechanisms of four agents on the stability of ITO suspension can be explained as follows: PP is of steric hindrance, TC and BA are of electrostatic hindrance and MC is of electrostatic and steric hindrance. ITO thin film was prepared by the spin coating process of spreading membrane on the ITO ethanol absolute suspension uniformlue. The block resistance of the film is 196Ω/□, the transmittance of the visible light is equal to or more than 87.8%, and the reflectance of the infrared light is about 70%.Based on the sol-gel of chemie douce, IO/SiO₂ and ITO/SiO₂ mesoporous nanocomposite were synthesized by immersion- pyrolysis. The results showed that the mesoporous composite ITO/SiO₂ has the better photoluminescence enhancement effect than IO/SiO₂ with the peak intensity value of 504, when excited wave length is 275nm, the emitted wave length in the position of 360nm. Based also on the sol-gel of chemie douce, SiO₂ aero gel and IYO/SiO₂ aero gel were prepared by gel- mixing drying method. The results showed that ITO/SiO₂ aero gel has the better photoluminescence enhancement effect than SiO₂ aero gel with the peak intensity value of 1647, when excited wave length is 220nm, the emitted wave length in the position of 398nm, and at this moment, its PL spectrum has had the right offset, which is 15nm. Thus from the results mentioned above, ITO/SiO₂ aero gel has the best photoluminescence properties among the mesoporous nanocomposites prepared here.Review of the preparation, performance and application of ITO nanomaterials in China and abroad was given in this dissertation. The preparation principle, dispersion stability theory and mechanism of semiconducting of ITO nanomaterials were analyzed. ITO nanopowder was prepared by precursor-pyrolysis method, ITO suspension was prepared by ball milling and ultrasonic cavitations dispersion method, ITO/SiO₂ mesoporous composite was synthesized by gel- mixing drying method and immersion- pyrolysis. A useful exploratory experiments of ITO nonmaterial in its preparation technology, forming mechanism, physical performance and influence factors lay the basis of development and application of heat insulation or photoluminescence composites, and new type functional composites of ITO.更多还原