24小时热门版块排行榜

返回列表

当前主题已经存档。

ahs790808

铁杆木虫 (职业作家)

大魔导师

应助: 4 (幼儿园)
金币: 9219.4
散金: 864
红花: 1
帖子: 3276
在线: 183.5小时
虫号: 409456
注册: 2007-06-22
专业: 无机非金属类光电信息与功

[交流] 在纳米颗粒中观察到的特殊相转变和生长路径

Abstract
Phase transformation and crystal growth in nanoparticles may happen via mechanisms distinct from those in bulk materials. We combine experimental studies of as-synthesized and hydrothermally coarsened titania (TiO2) and zinc sulfide (ZnS) with thermodynamic analysis, kinetic modeling and molecular dynamics (MD) simulations. The samples were characterized by transmission electron microscopy, X-ray diffraction, synchrotron X-ray absorption and scattering, and UV-vis spectroscopy. At low temperatures, phase transformation in titania nanoparticles occurs predominantly via interface nucleation at particle–particle contacts. Coarsening and crystal growth of titania nanoparticles can be described using the Smoluchowski equation. Oriented attachment-based crystal growth was common in both hydrothermal solutions and under dry conditions. MD simulations predict large structural perturbations within very fine particles, and are consistent with experimental results showing that ligand binding and change in aggregation state can cause phase transformation without particle coarsening. Such phenomena affect surface reactivity, thus may have important roles in geochemical cycling.
[search]http://www.pubmedcentral.nih.gov/articlerender. ...[/search]

回复此楼