Molecular dynamics simulation of Anatase TiO2 nanoparticles

Nanoparticles, which are desirable to a wide range of industries, have been shown to exhibit enhanced properties compared to their bulk counterparts. This enhancement has mostly been attributed to their large surface area-to-volume ratio and has attracted huge research interest in recent years. In this work, molecular dynamics simulations have been performed on anatase TiO2 nanoparticles with sizes ranging between 2 and 6 nm and at different temperatures. Thermodynamic and structural properties such as total system energies and radial distribution functions are reported for the different nanoparticle sizes and their dependence on temperature, revealed. At high temperatures, the structures are seen to transform from a highly crystalline to liquid form. Studies conducted on the change of final structure (after simulation) with respect to the initial structure (before simulation) revealed that after simulation, structural disordering (i.e., change in atom position) is more visible at the surface layer compared to the bulk of the final structure. Surface energies for the different particle sizes are also reported and it is observed that surface energy at 300 K increases to a maximum (optimum value) as the particle size increases after which no further significant increase is observed. A study on the sphericity of the nanoparticles showed that the particles became less spherical with increase in temperature.