Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Langmuir. 2012 Feb 28;28(8):3722-9. doi: 10.1021/la204002b. Epub 2012 Feb 16.
In polyol processes, it was widely accepted that Ag nanowires (NWs) were formed via uniaxial growth of multiple twinned decahedral particles (MTPs) along the {111} facets. Herein, we show that the above MTP uniaxial growth mechanism for growth of nanorods (NRs) and short nanowires (NWs) is different from that for the growth of long Ag NWs. We provide experimental evidence to show that polycrystalline long Ag NWs (up to 100 μm) could be formed in high yield (90%) by a completely different growth mechanism via self-assembly of Ag NPs/NRs. Transmission electron microscope (TEM) measurements show that long Ag NWs are composed of crystalline Ag NPs and NRs with multiple crystal orientations, and many NRs have crystalline structures with pentagonal cross section. Solution phase in situ X-ray diffraction (XRD) measurements show that a strained face-centered tetragonal (fct) phase was gradually formed during the formation and growth of long Ag NWs, in addition to the normal face-centered cubic (fcc) phase. The strained fct phase disappears after partial etching by HAuCl(4) and Fe(NO(3))(3). The working conditions for the MTP uniaxial growth mechanism and the current nitrate-promoted self-assembly growth mechanism will be compared and discussed.
在多元醇工艺中，人们普遍认为银纳米线（NWs）是通过多个孪晶十面体（MTP）沿着{111}面的单轴生长形成的。在此，我们表明，上述 MTP 单轴生长机制对于纳米棒（NRs）和短纳米线（NWs）的生长与长银 NWs 的生长机制不同。我们提供了实验证据表明，多晶长银 NWs（长达100μm）可以通过 Ag NPs/NRs 的自组装以完全不同的生长机制高产率（90%）形成。透射电子显微镜（TEM）测量表明，长银 NWs 由具有多个晶体取向的结晶 Ag NPs 和 NR 组成，并且许多 NR 具有具有五边形横截面的结晶结构。溶液相原位 X 射线衍射（XRD）测量表明，在长银 NWs 的形成和生长过程中，除了正常的面心立方（fcc）相之外，还逐渐形成了应变面心四方（fct）相。部分用 HAuCl(4)和 Fe(NO(3))(3)蚀刻后，应变 fct 相消失。将比较和讨论 MTP 单轴生长机制和当前硝酸盐促进的自组装生长机制的工作条件。
