Professor Tim Myers and PhD student Claudia Fanelli have published a new article on the Journal of Colloid and Interface Science (24/10/2018)

Oct 24, 2018


How to grow nanocrystals

At the heart of nanotechnology is the nanoparticle or nanocrystal: the basic building block of many nanoscale components. It is estimated that semiconductor nanocrystals alone will have a value of around $4 billion by 2020. Perhaps the most common method for manufacturing nanocrystals is by growing them in a colloidal solution. Since nanocrystal properties depend on their size and/or shape it is essential to be able to produce monodisperse (having the same size) crystals by this technique. However, the theory to guide this process is not well understood and so currently production is limited to small batch processes and trial and error. 
The current understanding of nanocrystal growth is based on what is termed LSW theory, which arises from analysis of monomer diffusing in the solution to the growing nanocrystal. Key (unknown) parameters are the diffusion coefficient and the surface reaction coefficient. In the past researchers have fitted experimental data to the results of the mathematical model using up to eight parameters. Agreement with data is often poor and may not be suitable for guiding experiments.
In Myers & Fanelli, 2018, it is shown that all previous researchers in this field have incorrectly analysed the mathematical model. A rigorous analysis shows that the standard diffusion model only holds after approximately 100s growth and so early data points must be neglected when fitting data. It is also shown that the model cannot distinguish between surface kinetics and diffusion, explaining why researchers have been able to fit data using either model. Using the correct model it is shown that an excellent fit (more accurate than all previous results) may be obtained with a single parameter. Also, for the first time, an explicit relation showing the evolution of the particle radius with time was presented. Hopefully this analysis, published in one of the top journals in the field, will be used to guide and optimise future nanocrystal production.
Myers TG and Fanelli C. On the incorrect use and interpretation of the model for colloidal, spherical crystal growth. J. Colloid and Interface Science, 536 (2019) 98–104.

You can read the article here