Effects of synthetic conditions and heat-treatment on the structure of partially ion-exchanged titanate nanotubes
Effects of synthetic conditions and heat-treatment on the structure of partially ion-exchanged titanate nanotubes
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DOI：
10.1016/j.matchemphys.2004.12.010
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发表时间：
2005-06
影响因子：
4.6
通讯作者：
Ryuhei Yoshida;Yoshikazu Suzuki;S. Yoshikawa
中科院分区：
文献类型：
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作者：
Ryuhei Yoshida;Yoshikazu Suzuki;S. Yoshikawa
通过在 NaOH（水溶液）中水热处理制备的 TiO2 衍生纳米管的组成和形成机制已得到广泛研究。以往的报道存在一些矛盾，例如提出了晶体结构和热稳定性。以往工作中加工条件和纳米管中钠残留的一些差异导致了纳米管的结构、热稳定性等方面的混乱。在本文中，研究了标称成分为~H1.5Na0.5Ti3O7 的明确含钠（即部分离子交换）纳米管在水热和后热处理过程中的微观结构变化。在120℃的水热处理下，直到12h，纳米管才开始增长，并在12h以上变得几乎恒定长度。通过350℃以上的后热处理，一些纳米管开始分解成锐钛矿相颗粒，而另一些纳米管仍以存在大量Na的纳米管形式存在，表明残留的Na稳定的纳米管结构。在较高的热处理温度下，颗粒转变为金红石相，纳米管转变为Na2Ti6O13纳米棒。原位高温扫描电镜研究也阐明了它们在加热过程中的结构变化。
TiO2-derived nanotubes prepared by hydrothermal treatment in NaOH (aq.) have been widely studied with regard to their composition and their formation mechanism. There exist some contradictions among previous reports, e.g. proposed crystal structure and thermal stability. Some difference of processing conditions and remnant sodium in nanotubes in previous works lead to the confusions on nanotubes’ structure, thermal stability, and so on. In this paper, microstructural change during the hydrothermal and post-heat-treatments was studied for well-defined sodium contained (i.e. partially ion-exchanged) nanotubes, with nominal composition of ∼H1.5Na0.5Ti3O7. Under the hydrothermal treatment at 120°C, the nanotubes grew longer until 12h, and became almost constant length for more than 12h. By the post-heat-treatment above 350°C, some of the nanotubes began to break into particles of anatase phase, and the others remained as nanotubes where a lot of Na existed, indicating the remnant Na stabilized nanotube structure. At higher heat-treatment temperatures, the particles changed into rutile phase, and the nanotubes converted into Na2Ti6O13nanorods. In situ high-temperature SEM study also clarified their structural change during heating.