Morphology development and crystal growth in nanocrystalline aggregates under hydrothermal conditions: Insights from titania
Morphology development and crystal growth in nanocrystalline aggregates under hydrothermal conditions: Insights from titania
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DOI：
10.1016/s0016-7037(99)00037-x
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发表时间：
1999-05-01
影响因子：
5
通讯作者：
Banfield, JF
中科院分区：
文献类型：
--
作者：
Penn, RL;Banfield, JF
使用高分辨率透射电子显微镜 (HRTEM) 和 X 射线衍射 (XRD) 峰展宽 (Scherer) 分析来研究纳米晶体的粗化和形态发展。实验工作使用直径约为 5 nm 的合成等维锐钛矿 (TiO2) 颗粒。在水热条件下（100-250摄氏度，15-40巴），沿着[001]发生快速生长，部分是由（001）相对较高的表面能驱动的，部分是由涉及高反应性吸附位点循环生成的动力学效应驱动的。沿[001]的快速生长会抑制生长速率，直到（001）表面收缩至临界簇尺寸。第二个主要粗化机制显着降低表面能，特别是在酸性条件下。这种机制涉及初级粒子在高能表面（最常见的是{112}，较少见的是（001））的拓扑附着，并且可以产生细长的单晶。在实验室和自然环境中遇到的各种条件下，定向附着可能是一种重要的粗化机制。版权所有 (C) 1999 爱思唯尔科学有限公司
High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) peak broadening (Scherer) analysis were used to study coarsening and morphology development of nanocrystals. Experimental work used synthetic, equidimensional anatase (TiO2) particles about 5 nm in diameter. Under hydrothermal conditions (100-250 degrees C, 15-40 bars), rapid growth occurs along [001], driven in part by the relatively high surface energy of (001) and in part by a kinetic effect involving a cyclic generation of highly reactive adsorption sites. Rapid growth along [001] depresses the growth rate until (001) surfaces shrink to a critical cluster size. A second major coarsening mechanism significantly reduces the surface energy, especially under acidic conditions. This mechanism involves topotactic attachment of primary particles at high energy surfaces (most commonly {112}, less commonly (001)) and can result in elongate single crystals. Oriented attachment may be an important coarsening mechanism under a wide range of conditions encountered in the laboratory and in natural environments. Copyright (C) 1999 Elsevier Science Ltd.