The Large Scale Synthesis of Aligned Plate Nanostructures

Abstract

We propose a novel technique for the large-scale synthesis of aligned-plate nanostructures that are self-assembled and self-supporting. The synthesis technique involves developing nanoscale two-phase microstructures through discontinuous precipitation followed by selective etching to remove one of the phases. The method may be applied to any alloy system in which the discontinuous precipitation transformation goes to completion. The resulting structure may have many applications in catalysis, filtering and thermal management depending on the phase selection and added functionality through chemical reaction with the retained phase. The synthesis technique is demonstrated using the discontinuous precipitation of a γ′ phase, (Ni, Co)3Al, followed by selective dissolution of the γ matrix phase. The production of the nanostructure requires heat treatments on the order of minutes and can be performed on a large scale making this synthesis technique of great economic potential.

Invited viewpoint: in situ nanostructured lamellar composites

“…Amount of DP Conditions Al-Zn [9] 95 vol.% 100-180 °C, \ 1.5 h Al-Co-Ni [14] 100% 550-650 °C, \ 2 h AZ80-Ag [15] 100% 175 °C, 38 h Cu-Ag [10,11] [ 30% 300-400 °C Cu-Cd [16] 100% 350 °C Cu-20 wt.%Ni-20 wt.%Mn [17] 100% 350 °C, 96 h Cu-4.3 at.% Ni-2.2 at.%Si [18,19] [ 95% 450 °C, 120 h Cu-4 at.%Ti [12] Nearly complete 450 °C, 120 h Pd-rich Paliney alloy [20] 100% 450-500 °C, 240 h temperature range in which the DP structures are usable.…”

The Formation Mechanism of a Self-Organized Periodic-Layered Structure at the Solid-(Cr, Fe)2B/Liquid-Al Interface

“…The periodic-layered structure (PLS) is a kind of in-situ nanocomposites, and has attracted much attention due to its interesting layered microstructure features and their potential application in novel energy conversion materials and electrocatalytic performance [ 1 , 2 ]. The PLS is a kind of self-organized structure formed by reaction-diffusion and has found in numerous alloy systems, such as Ni 3 Si/Zn [ 3 , 4 , 5 , 6 ], Cu x Ti y /Zn [ 7 ], SiO 2 /Mg [ 8 , 9 , 10 ], (Ni, W)/Al [ 11 ], U-Mo/Al [ 12 ], and so on.…”

Research Progress of Biomimetic Self-assembly of Nanomaterials in Morphology and Performance Control

“…米器件，实现对单个纳米颗粒的排布、纳米结构单 元构筑以及在纳米尺度上加工过程的有效调控，是 实现纳米器件结构功能一体化的关键 [7] 。目前常用 的纳米材料制备方法如气相沉积法 [8] 、水热合成法 [9][10] 、 层层自组装法 [11] 、 沉淀法 [12] 、 溶胶-凝胶法 [13][14][15][16] 等等，尚不满足或不完全满足这一要求。 自然界中，DNA 分子的双螺旋结构 [17][18] 、蛋白 质的聚集与折叠 [19] 都展示出普遍存在的自组装现 象 [20,21,26 ] 。自组装过程是若干结构单元之间同时自 发关联并结合在一起，形成一个有序整体的复杂协 同作用。随着仿生学和现代科学技术的快速发展， 仿生自组装技术引起科学家的广泛关注，在电子 [22] 、 信息 [23] 、材料 [24][25] 和生命 [26][27] 等众多领域占据越来 越重要的地位。通过仿生自组装技术，借助分子间 作用力自发形成稳定并具有特定结构和功能的微纳 米尺度结构 [28] ，已经成为制备纳米材料和器件的重 要 手 段 和 方 法 之 一 。 自 组 装 技 术 是 " 自 下 而 上 (Bottom-up)"方法中的重要技术手段， 这种合成方式 可以代替传统的"自上而下 (Top-down) "加工技术， 实现单个原子或分子在纳米尺度上构造特定结构和 功能的器件 [29][30] [32] ，(b)基于屏蔽效应自组装表面纳米图案的路线图 [37] Fig. 1 (a) Schematic procedure of micropattern fabrication employing a shielding reagent [32] ; (b) Route of self-assembled surface nanopatterns based on shielding effect [37] 上述研究结果表明， 高表面能域更适合组装高表 面张力的功能材料，而低表面张力的有机液体(如 醇、四氢呋喃、甲苯和二甲基甲酰胺等)或聚合物 溶液组装难度较大 [33][34][35] ，这主要归因于有机溶剂和 聚合物溶液表面张力较低(γLV∼15~30 mN/m) ，更 倾向于在低表面能域与非极性基团形成"屏蔽线性 分子" 。在自组装过程中，衬底表面既有低表面能的 "屏蔽"区域，又有高表面能的极性基团区域，两 者之间不对称的分子间作用力促使功能材料实现位 相选择组装。研究发现，针对不同的材料体系，不 同官能团的屏蔽剂对位相选择的影响有显著不同 [36] 。 Sagiv 等 [37] [38] 和 Binks [39] 的研究发现，微米级的固 体粒子能在双液相界面形成一层稳定的薄膜，即 [38][39] ; (c) Changes of surface tension when particles with radius rare adsorbed on the oil-water interface…”