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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - NanoDome (Nanomaterials via Gas-Phase Synthesis: A Design-Oriented Modelling and Engineering Approach)

Teaser

Summary

The main objective of the NanoDome project is to develop a robust model-based design and engineering toolkit for the detailed prediction of complex nanomaterial structures produced in a commercially-relevant generic bottom-up Gas-Phase (GP) synthesis process, to improve the control of the nanomaterial production and the industrially-scalable GP synthesis process for more accurate final product properties (e.g. particle size, surface area, structure, chemical composition, morphology and functionalization coatings) and provide potential end-users with a validated tool based on scientific principles that enables predictive design of novel nanomaterials and novel GP production routes thereby shortening their development process.

This will be pursued by combining computational modelling, software development and systematic validation activities at lab- and industrial-scale in a three-year project.

Existing meso-scale nanomaterial GP synthesis modelling approaches (Lagrangian and stochastic) will be extended and integrated with continuum-scale reactor models to provide a fully functional single discrete mesoscopic model for the evolution of the nanoparticle population inside a control volume as a function of time, together with detailed description of nanoparticle composition and internal structure (e.g. core-shell, multi-layer, radially-dependent composition), particle interaction, coagulation and morphology.

Industrial and lab-scale validation will focus on a set of target materials of great impact for the EU, using technologies currently at TRL4-6.

The work proposed in the NanoDome project addresses the aforementioned challenges by delivering a modelling and analysis tool for the detailed prediction of complex nanomaterial structures formation in a single-step and industrially scalable GP synthesis process, in order to optimize existing processes, shorten the development of new processes and increase the production rates.

Work performed

The work performed between M1 and M18 has been focused on three main objectives:

- Mesoscopic model definition and software implementation
A detailed physical mathematical model has been defined in the first months of the project, followed by the definition of suitable data structures, object hierarchy and numerical algorithms to be used as guide for code development. After preliminary testing, the software implementing the mesoscopic model has been applied to a realistic case of Si synthesis in an Ar plasma reactor. Besides that, interfacing libraries between mesoscopic and continuum have been developed and released.

- Atomistic simulation of fundamental nanoparticle properties and mechanisms
Classical MD modelling using ReaxFF potentials has been performed to provide information on atomic scale mechanisms such as embryo cluster size, homogeneous/heterogeneous nucleation and sintering rates, to be used as fundamental data in the meso-scale model. In this period the work focused mainly on non-reactive systems. A preliminary work on the development of ad hoc parameters for atomic scale material systems for the ReaxFF potential has been performed, increasing the accuracy of the potential with respect to literature state of the art.

- Chemical kinetics and validation
Deatailed chemical kinetics for the relevant synthesis routes have been formulated and a hierarchy of reduced schemes has been developed for the simulation of chemical kinetics in the mesoscopic and continuum models. Feasible validation means have been defined and developed. Simplified hot-wall and plasma reactor models have been developed for validation purposes.

In the last six months of the first reporting period, we started to define industrial cases for the testing of the NanoDome model in a relevant industrial environment.

Final results

Progress beyond the state of the art includes:

- Definition of new and more accurate ReaxFF parameters for Si and ZnO in reactive environments with respect to existing literature. These results will enable researchers in a wide range of fields to improve the accuracy of MD simulations and to provide a comparisons between results.

- New insights on the mechanisms of nucleation, sintering and surface condensation on nanoparticles, including nanoparticles interaction potential formulation.

- Equations describing hierarchies of novel chemical kinetic mechanisms and new closure equations with varying levels of detail have been delivered, describing precursor chemistry about which little to no information is available in the literature at present. These new chemical mechanisms for different material systems are part of the new physics that is delivered by the project.

- The mesoscopic model definition and software is a first of a kind integration of different sub-models describing single mechanisms in nanoparticle synthesis from gas phase in a single framework. The NanoDome model will help to develop a common approach in the aerosols simulation, facilitating the use of the software by a wider range of possible users.