Study of Titanium Dioxide Nanoparticles via Molecular Dynamics Simulations

Abstract

Molecular dynamics simulations are used to study various aspects of nanoparticles of anatase and rutile, which are the two most abundant polymorphs of titanium dioxide (TiO2). The phenomenon of sintering of nanoparticles is examined via simulation and later compared with phenomenological models designed for micron-sized particles. The effect of particle size, phase, orientation and temperature on the process of nanoparticle sintering is determined. The dipole-dipole interactions and particle orientations are found to play a vital role in nanoparticle sintering. The structure of water in the vicinity of anatase and rutile nanoparticles in ambient and hydrothermal aqueous environment is determined using constant pressure and temperature simulations. The low solubility of TiO2 nanoparticles in water corroborates the results obtained. Molecular dynamics simulations are also used to study phase transformations that occur when two or more TiO2 nanoparticles with different phases interact with each other while sintering. At temperatures in the proximity of nanoparticle melting points, phase transformations to the most stable phase are observed.