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基于二氧化钛的纳米钛酸锶一步水热合成基础研究
张亚兵
学位类型硕士
导师段东平
2016-07
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业化学工程
关键词钛酸锶 二氧化钛 水热合成 纳米颗粒
摘要

钛酸锶是一种典型的钙钛矿型复合氧化物陶瓷材料,有着非常优异的光催化、压电、铁电性能,在光催化剂、太阳能电池、压敏电阻、陶瓷电容器等领域具有非常巨大的应用前景。传统上钛酸锶粉体的主要制备方法是高温固相烧结法,但是高温固相烧结法所制备的钛酸锶粉体纯度低、粒径大、粒度分布不均匀、团聚现象严重,而且高温烧结过程能耗大、环境污染严重。 为了克服高温固相烧结法的缺点,近年来多种湿化学已经被用来制备钛酸锶材料,主要有溶胶-凝胶法、化学沉淀法、水热法等。其中水热法是一种非常有前景的粉体材料制备方法。本文即以此为背景,采用单步直接水热法以晶体二氧化钛为钛源、以八水合氢氧化锶为锶源来制备钛酸锶纳米粉体。首先,反应物是大宗化工产品,无毒无害、廉价易得,具有工业化应用前景。其次,水热法提供了一种特殊的物理化学环境,钛酸锶纳米粉体一步直接合成,不需要再进行高温煅烧,避免了粉体的团聚;最后,所制备的钛酸锶纳米粉体纯度高、粒径小、粒度分布均匀,具有较大的比表面积。 本论文的研究重点是以四种不同类型的二氧化钛(普通锐钛矿型、纳米锐钛矿型、纳米金红石型和P25型)作为反应原料,通过单因素和多因素实验,综合考察了反应温度、反应时间、物料配比以及氢氧化钠溶液浓度对于钛酸锶纳米粉体纯度、晶体结构、粒径、粒度分布、形貌以及比表面积的影响,并对合成过程的机理进行了揭示。 主要的研究结论有:四种不同类型的二氧化钛活性差异较大。其中活性最低的是普通锐钛矿型二氧化钛,它完全反应生成钛酸锶所需条件最为严苛;其次是纳米金红石型二氧化钛,其完全反应生成钛酸锶条件有所降低;再次是纳米锐钛矿型二氧化钛,纳米锐钛矿型二氧化钛活性较好,其完全反应生成钛酸锶的条件显著降低;P25型二氧化钛是四种二氧化钛中活性最高的。四种二氧化钛活性差异较大,主要在于其比表面积的不同。P25型二氧化钛的比表面积最大,故而其活性最好,反应时接触面积大,所需反应条件显著降低。最后论证了二氧化钛单步直接水热合成钛酸锶纳米颗粒的反应机理可以用溶解-沉淀反应机理来解释。 

其他摘要

Strontium titanate (SrTiO3) is a kind of typical perovskite mixed-metal oxide functional ceramic material, which has outstanding photocatalysis, piezoelectricity, and ferroelectricity properties and has been extensively applied in photocatalysts, solar cells, piezoresistors, and capacitors. Traditionally, the main preparation of SrTiO3 is high temperature solid state sintering method. This is the domain preparation method in industrialization production and scientific research; however, SrTiO3 powders prepared by this method has low purity, large particle size, bad size distribution, and serious agglomeration. In addition, the high temperature solid state sintering method also wastes great energy and causes severe environment problems. In order to overcome these disadvantages, various liquid phase methods to synthesize SrTiO3 perovskite ceramic materials have been reported including sol–gel method, solution-precipitation method, and hydrothermal route. Among these methods, hydrothermal synthesis is a promising powders preparation method. Based on this, SrTiO3 nanopowders were successfully synthesized by a single-step direct hydrothermal process using crystalline titanium dioxide (TiO2) and strontium hydroxide octahydrate (Sr(OH)2·8H2O) as the starting materials. Firstly, the reactants is ordinary chemical products that have no toxicity and are cheap and easily got. Furthermore, hydrothermal route provides a special physical chemistry condition to synthesize SrTiO3 by a single-step direct hydrothermal process rather than high temperature sintering. So the serious agglomeration can be avoided. Finally, the nanoparticles synthesized by hydrothermal method has small nanoparticles with uniform size, high crystallinity, regular morphology, and large specific surface areas.We took four kinds of TiO2 as the starting materials and researched the influences reaction temperature, reaction duration, ratio of the starting materials, and NaOH solution concentration to purity, crystal structure, crystalline size, distribution of particle size, morphology, and specific surface area of SrTiO3. The main results are: Four kinds of TiO2 have different activities. Among them, conventional anatase TiO2 has the strictest conditions to synthesize SrTiO3 completely; secondly, nano rutile TiO2 has little bigger activity than conventional anatase TiO2; thirdly, nano anatase TiO2 has the good activity and obvious lower reaction conditions; P25 TiO2 has the biggest activity among the four kinds of TiO2. Different activity of four kinds of TiO2 is based on their different specific surface areas. P25 TiO2 has the biggest specific surface area. So it can be converted to SrTiO3 nanoparticles under the lower reaction conditions. Finally, the single-step direct hydrothermal synthesis of strontium titanate using TiO2 can be elaborating by dissolution-precipitation reaction mechanism.

语种中文
文献类型学位论文
条目标识符http://ir.ipe.ac.cn/handle/122111/22869
专题研究所(批量导入)
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张亚兵. 基于二氧化钛的纳米钛酸锶一步水热合成基础研究[D]. 北京. 中国科学院研究生院,2016.
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