Controlled growth of two-dimensional ‘single-crystal’ hafnia networks by surface modulation

Abstract

Two-dimensional ‘single-crystal’ hafnia networks were synthesized by the high temperature gas–solid reaction method. Transmission electron microscopy investigation shows that these networks exhibit micrometre-scale external dimensions and nanometre-scale holes and frame width. The formation of these novel structures is based on the vapour–solid growth mechanism, and the boron nitride deposited on the networks’ surface plays a key role in the growth procedure by selectively influencing the growth rate of the crystal faces. This process involves the control of crystal surface properties and adsorption of the growth unit, and is extendable to the fabrication of nanosystems either in two dimensions or in three dimensions.

Texture, Twinning, and Metastable “Tetragonal” Phase in Ultrathin Films of HfO[sub 2] on a Si Substrate

“…These would become possible twin planes of the structure, and all these twinning modes were previously observed in ZrO 2 or HfO 2 . 12,17,18…”

Growth of Gold Nanoplates: The Case of a Self-Repair Mechanism

“…On the other hand, the slow reduction of AuCl 4 under as-used condition might also improve the coalescence of the initially formed nanoparticles. 16 The HRTEM image, Figure 2 in the Supporting Information, shows that the bulges include many atom steps and the primary adsorption may occur on kink sites, step edges, or corners, resulting in the preferential growth of this part; 23 that is, the bulges will act as the growth fronts. Interestingly, many bulges were found to appear as opposite couples, as shown in areas A and B areas in Figure 3d.…”

“…It is well-known that the key step of crystal growth is the adsorption of particles on the crystal surface . In this case, the attachment and fusion of small particles onto the edges of the pores were observed to form the new surfaces, which were considered to act as growth front, and the extension occurred on them, which would cause the closure of the pores in the nanoplates.…”

Morphological transition of gold nanostructures induced by continuous ultraviolet irradiation

“…Thus, to investigate the rational approaches in preparing desired nanostructures is a basic and crucial step towards the application of nanomaterials. Many nanostructures, such as nanocubes [2,9,10], nanocages [11,12], nanonetworks [13][14][15][16][17][18] nanorods/nanowires [19], nanodiscs/nanoplates [20][21][22], and bipyramid-shaped nanoparticles [24], as well as branched/dendritic nanocrystals [3,7,10], have been routinely synthesized. The size and shape-controlled synthesis of metal nanostructures induced by photo-irradiation has been proved to be highly effective.…”