【作者】 汪文娟；

【导师】 黎先财；

【作者基本信息】 南昌大学 ， 无机化学， 2005， 硕士

【摘要】 WO₃在电致变色、催化、气敏性等方面均具有优良性能,是一种具有广阔应用前景的多功能材料。因此研制开发超细或纳米WO₃,并用于新材料的制备,是很有潜力的一个研究方向。 本文以APT、H₂WO₄、W等为起始物,采用正交设计实验,通过水热法合成了超细WO₃粉体。考察前驱物、水热反应及热处理过程中的各因素对产物性能的影响,并对其合成条件进行了探讨。通过激光粒度仪、比表面测定仪、XRD、TEM和TG-DTA对样品粒度、比表面、晶型、形貌、失重情况等进行分析表征。 以APT为前驱物,通过高温固相煅烧、HCl酸化沉淀法和水热晶化法制备超细WO₃。其中水热晶化法有利于介稳态六方WO₃的形成和晶粒的完整发育,但水热晶化造成的软团聚使晶粒尺寸较大,介于0.25-1.2μm之间。 以H₂WO₄为原料,通过高温固相煅烧和水热晶化法制备超细WO₃。其中,水热法制得的晶粒尺寸在0.03-0.15μm之间,但水热晶化温度对产物粒度有较大影响,温度升高粒度也随之增大。 以金属钨粉为原料,H₂O₂氧化钨粉生成的过氧聚钨酸为前驱体,经水热反应得到WO₃及其水合物。结果表明:前驱物制备过程中各因素对产物的粒度及分布、比表面有一定影响;对产物物相、形貌、晶粒度影响较大的是水热处理温度、时间等。当水热处理温度和时间不充分时,不能完全形成WO₃,而是出现WO₃·0.33H₂O;温度和时间充分时,则无需后处理即可得到纯WO₃粉体。水热晶化有利于介稳态六方WO₃的形成,晶化温度越高,时间越长,越有利于晶化的完全,这样就能得到分布均匀,介于35-120nm的规则六方形纳米WO₃;但随晶化温度的进一步升高和时间的延长,六方WO₃易转变为单斜WO₃。同样,后处理会增大产物粒度,产物更多的形成单斜WO₃。 水热法制备WO₃,合成产物的粒度小且分布较均,远小于固相高温氧化所得产物的粒度,且有利于形成介稳态六方WO₃,为其在二次锂电池中的应用提供一定的合成基础。更多还原

【Abstract】 WO₃ is a kind of multi-functional material with perfect performances in fields of electrochromism, catalysis and gas-sensitivity, etc. It is a great potential research that ultra-fine WO₃ is developed in new materials.In this paper, APT, H₂WO₄ and W as precursors, the ultra-fine WO₃ powder has been yielded in orthogonal experiments via hydrothermal crystallization method, respectively. The effects of precursors, hydrothermal synthetic conditions and heat treatment on properties of products have been investigated. The products have been characterized using laser scattered particle analyzer, specific surface areas measuring and testing instruments, XRD, TEM and TG-DTA.APT as precursor, ultra-fine WO₃ was yielded by calcination, hydrochloric acid acidification-deposition and hydrothermal, respectively. Hydrothermal crystallization is in favor of forming hexagonal WO₃ and integrity crystal, but the granularity of product is from 0.25 to 1.2 μm due to soft-aggregation.H₂WO₄ as start material, ultra-fine WO₃ was prepared by calcination and hydrothermal. The granularity of product was between 0.03 and 0.15 u m. Hydrothermal temperature effects granularity of produa. The temperature higher, the granularity bigger.Tungsten trioxide and its hydrates were synthesized by hydrothermal method, peroxotungstic acid as precursor, which using a route based on the dissolution of tungsten metal powder in an excess of hydrogen peroxide solution （30%）to give. Theresults indicated that granularity, the distribution of granularity and the B.E.T. were influenced by some factors in preparation of precursor. Hydrothermal treatment temperature and time had great effects on the phase, morphology and particle size. In case of inadequate treatment temperature or time, orthogonal WO3-0.33H2O and monoclinic WO3 were yielded. And orthogonal WO3-0.33H2O disappeared in condition of higher temperature or adequate time. It seems that hydrothermal crystallization treatment is benefit to form hexagonal phase of WO3, and high temperature and long time help to a high degree of crystallization. In addition, hexagonal WO3 is apt to transform to monoclinic WO3 according to higher temperature or longer time. The characterization showed that WO3 powder between 35 and 120nm was yielded by this method and the particle was regular. However, the upper heat treatment increases the granularity and forms monoclinic WO3 to a greater extent.WO3 prepared by hydrothermal is smaller than that by calcination. Hydrothermal is benefit to form semi-steady hexagonal WO3, which provides a good base for its application in Li-batteries.更多还原