【作者】 周莉；

【导师】 宁桂玲； 贡卫涛；

【作者基本信息】 大连理工大学 ， 化学工艺， 2010， 硕士

【摘要】 二氧化钒(VO2)是一种具有相变性质的金属氧化物,其相变温度为68℃,相变前后结构的变化导致其产生对红外光由透射向反射的可逆转变,人们根据这一特性将其应用于制备智能控温薄膜领域。目前,相关方面的研究集中在通过溅射法、沉积法或溶胶——凝胶法等直接制备VO2无机薄膜,但制膜设备及原料价格昂贵,成膜面积小,不适合规模化生产。而细粒度的VO2粉体由于显著减少材料相变时的应力,并且随着粒度的减小,光透过率增加,将其加入到有机高聚物中制备的VO2有机复合薄膜则能够克服无机膜的上述缺陷,具有相当广泛的应用前景。但是,有关基于VO2粉体的有机薄膜的报道甚少,主要表现在缺少具有低温相变功能的VO2超细粉体的工业化制备方法,并且在粉体改性方面研究不足。本论文采用高温熔融的方法实现了对VO2粉体有效掺杂,将其相变温度降至室温附近,并且通过共沸蒸馏的方法解决了溶胶—凝胶过程中的粉体硬团聚问题,制备出具有低温相变性能的V02超细粉体。为了改善粉体与有机介质的相容性,还尝试了对VO2粉体进行表面改性。本文主要研究内容、方法和结果如下：1实验研究了不同掺杂剂对VO2粉体相变性能的影响。采用五氧化二钒(V2O5)与掺杂剂高温熔融、水淬的方法进行掺杂,再将得到的溶胶干燥后还原即制备出掺杂VO2粉体。通过选取不同的含钨的化合物作为钨掺杂剂,利用XRD、DSC、XPS、SEM等手段对掺杂VO2粉体的性能进行表征和分析,发现钨酸钠的掺杂效果在选用的含钨化合物中最好,平均每加入1at.%(与钒元素的摩尔质量比)的钨酸钠,VO2相变温度降低32℃。另外,选取钼酸钠作为掺杂剂对比不同掺杂元素的影响效果,结果表明平均每加入1at.%的钼酸钠,VO2相变温度降低20℃。2研究了采用共沸蒸馏法制备掺杂对VO2粉体相变性能的影响。通过改进上述工艺,在溶胶干燥之前选择正丁醇作为共沸溶剂进行共沸蒸馏,避免了颗粒硬团聚问题的产生,制备出尺寸较小、粒径分布较窄的VO2超细粉体。经过比较发现,采用共沸蒸馏法制备的掺杂钨酸钠或钼酸钠的VO2粉体的相变温度降低的幅度低于未进行共沸蒸馏的粉体,但相变焓值却增了一倍多。另一方面,通过改变共沸蒸馏后的V2O5粉体的煅烧温度,发现粉体形貌由颗粒状转变为纳米棒状,实现了具有一定形貌的V2O5粉体的可控合成。3初步研究了有关VO2粉体表面改性的方法。采用两种不同的途径对VO2粉体进行表面改性：(1)先以正硅酸乙酯(TEOS)为原料对粉体进行SiO2无机包覆,再与硅烷偶联剂反应,实现无机／有机双重包覆；(2)尝试用聚丙烯酰氯、聚乙二醇对粉体进行表面接枝改性。更多还原

【Abstract】 Vanadium dioxide (VO2) is one kind of metallic oxide with thermochromism property at phase transition temperature of 68℃. It can alter infrared transmittance by transforming crystal structure reversibly when phase transition occurs, that characteristic is applicable to prepare intelligent temperature-control films. At present, the research about relevant issues is focused on preparation of VO2 inorganic films though Sputtering, CVD, sol-gel, and so on. However, these methods need expensive instrument and raw material, besides the area of the films is limited, so that they are not suitable for large-scale production.It was reported that ultrafine powder of VO2 is capable of lessening the stress caused by the phase transition and to make light transmittance improved. The hybrid films made by adding the fine particle of VO2 to the polymer are able to overcome defects in VO2 inorganic films, which have infinite potential in application. Yet, there is seldom research on that field, because it’s lacking in mass production of VO2 ultrafine powder which possess the function of phase transition at low temperature, as well as the powder surface modification technique.In this dissertation, the VO2 was doped effectively to low the phase transition temperature via sol-gel method, combining with the azeotropic distillation procedure thermochromism VO2 micro powder were successfully synthesized, simultaneously we had tried to modify the powder in order to improve the compatibility between the inorganic particles and polymer. The primary contents, methods and results are as follows:1. Research on the VO2 phase transition properties doped by some different dopants. In this experiment, Vanadium pentoxide(V2O5) was doped by dopant through the elevated temperature fusion process, the result doped VO2 powder were achieved after reduced V2O5 by ammonia. By selecting different tungsten compounds as tungsten dopant, the performance of doped VO2 were characterized by means of XRD、DSC、XPS、SEM and so on, it was found that the powder doped by sodiumtungstate(Na2WO4) showed the best effect, the phase transition temperature of VO2 is decreased by 32℃with only lat.% Na2WO4 doped. Sodium molybdate (Na2MoO4) was chosed as molybdenum dopant, the phase transition temperature is reduced by 20℃with lat.% Na2MoO4 doped.2. Effect of azeotropic distillation on the phase transition behavior and powder morphology of doped VO2 powder had been investigated. The doped VO2 powder which has small size and good distribution was successfully prepared by an improved azeotropic distillation processing, which prevented the formations of agglomeration. With comparison, the reduced rate of phase transition temperature of VO2 doped by Na2WO4 or Na2MoO4 prepared by azeotropic distillation method were lower than the rate of which without azeotropic distillation, however, the enthalpy value has increased the more than doubled. On the other hand, the V2O5 nanorods were formed through changing calcination temperature growth from the nanocrystalline phase created after azeotropic distillation.3. Preliminary studies on VO2 powder surface modification method. Two different ways were used for VO2 powder surface modification:(1)Inorganic/organic surface treatment. First, the particle was coated by silica via hydrolysis of tetraethoxy silane(TEOS), and then modified by silane coupling agent. (2) Poly (acryloyl chloride) and poly (ethylene glycol) was covalently grafted onto the surface.更多还原