DUFFY1

Modelling stress in gold nanoparticles and cantilevers

Type

Theoretical

#students

   

Orientation

Why is the scientific problem of interest at all?

The properties of nanoparticles and nanocantilevers  are very different from those of the bulk material, due to the high surface to volume ratio of nanostructures. One example is the effect of surface stress on nanostructures. Stress is induced near the surface of all solids due to the lower coordination of the surface atoms. In bulk crystals this surface stress has little effect on the properties but in nanoscale particles the surface stress induces a finite stress in the centre of the particle and the magnitude of this stress increases as the size of the particle decreases. This effect can be investigated for spherical particles using continuum elasticity theory but such a theory is not appropriate for very small particles when the atomistic structure needs to be considered.

 

How

How is the research going to shed light on the given problem?.

We have recently developed a method for calculating the local stress from molecular dynamics simulations. Using this model we can calculate the stress in particles of arbitrary shape, size and charge. We have applied this to titania nanoparticles and found interesting behavior.

What

What is the specific thing that the student will do, and how does it fit inside the overall project?

 In this project we will study gold nanoparticles and calculate the variation in the stress with nanoparticle diameter. We will also model nanocantilevers with a range of surface terminations. It time permits the effects of adsorbed molecules on the stress, and the resultant bending, will be calculated which is relevant to the application of cantilevers as sensors.

Special Knowlegde

 

Supervisor

 Dr Dorothy Duffy d.duffy@ucl.ac.uk