Alavi Saman, Mintmire John W, Thompson Donald L
Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA.
J Phys Chem B. 2005 Jan 13;109(1):209-14. doi: 10.1021/jp046196x.
The oxidation of aluminum nanoparticles is studied with classical molecular dynamics and the Streitz-Mintmire (Streitz, F. H.; Mintmire, J. W. Phys. Rev. B 1994, 50, 11996) electrostatic plus (ES+) potential that allows for the variation of electrostatic charge on all atoms in the simulation. The structure and charge distributions of bulk crystalline alpha-Al(2)O(3), a surface slab of alpha-Al(2)O(3) with an exposed (0001) basal plane, and an isolated Al(2)O(3) nanoparticle are studied. Constant NVT simulations of the oxidation of aluminum nanoparticles are also performed with different oxygen exposures. The calculations simulate a thermostated one-time exposure of an aluminum nanoparticle to different numbers of surface oxygen atoms. In the first set of oxidation studies, the overall approximate ratios of Al to O in the nanoparticle are 1:1 and 2:1. The nanoparticles are annealed to 3000 K and are then cooled to 500, 1000, or 1500 K. The atomic kinetic energy is scaled during the simulation to maintain the desired temperature. The structure and charge distributions in the oxidized nanoparticles differ from each other and from those of the bulk Al(2)O(3) phases. In the Al(1)O(1) simulation, an oxide shell forms that stabilizes the shape of the particle, and thus the original structure of the nanoparticle is approximately retained. In the case of Al(1)O(0.5), there is insufficient oxygen to form a complete oxide shell, and the oxidation results in particles of irregular shapes and rough surfaces. The particle surface is rough, and the nanoparticle is deformed.
利用经典分子动力学和Streitz-Mintmire（Streitz, F. H.; Mintmire, J. W. Phys. Rev. B 1994, 50, 11996）静电加（ES+）势研究了铝纳米颗粒的氧化过程，该势允许在模拟中所有原子上的静电荷发生变化。研究了块状晶体α-Al₂O₃、具有暴露（0001）基面的α-Al₂O₃表面平板以及孤立的Al₂O₃纳米颗粒的结构和电荷分布。还对不同氧气暴露量下铝纳米颗粒的氧化进行了恒NVT模拟。计算模拟了铝纳米颗粒对不同数量表面氧原子的恒温一次性暴露。在第一组氧化研究中，纳米颗粒中Al与O的总体近似比例为1:1和2:1。将纳米颗粒退火至3000 K，然后冷却至500、1000或1500 K。在模拟过程中对原子动能进行缩放以维持所需温度。氧化后的纳米颗粒中的结构和电荷分布彼此不同，也与块状Al₂O₃相的结构和电荷分布不同。在Al₁O₁模拟中，形成了一个氧化壳，使颗粒形状稳定，因此纳米颗粒的原始结构大致得以保留。在Al₁O₀.₅的情况下，氧气不足无法形成完整的氧化壳，氧化导致颗粒形状不规则且表面粗糙。颗粒表面粗糙，纳米颗粒发生变形。
