Control of Interfacial Chemistry in Reactive Nanolaminates (CIREN) – CIREN

As part of a France-US Partnership Program, the proposed “Control of Interfacial Chemistry in Reactive Nanolaminates (CIREN)” project focuses on fundamental studies of a novel and exciting class of nano-energetic materials. It combines the expertise in nanomaterials synthesis and nanostructures of C. Rossi (LAAS, France) and in-situ spectroscopic characterization and surface chemistry of Y. Chabal (UTD, US) with materials theory of A. Estève (LAAS, France), necessary to develop a mechanistic understanding and control of the interface between highly reactive metal and metal oxide heterostructures.
Intellectual Merit: Reactive composite nanolaminates containing a metal (commonly Al) and metal oxide (commonly CuO, Fe2O3 and ZnO) have attracted great interest in the energetic material community since they are characterized by a high energy and power density (superior to supercapacitors), and offer compatibility with conventional microtechnologies; they are low cost and safe, useful for micro-thermal sources, micro-actuators and enablers for environmentally clean primers, miniature safe detonators, in-situ welding and soldering, and also chemical neutralization agents. Most investigations of these reactive and metastable nanostructures have focused on the relationship between the nanolaminate structure and the resulting thermal properties. Yet, interfaces play a critical role during the synthesis and the utilization of these reactive layered nanostructures. The formation of interfacial layers is not only poorly understood but uncontrolled at present. A fundamental understanding of the formation and role of these Al/Metal-oxide interfacial layers would not only bring control of such systems, but also be transformative for fundamental and practical advances in this field.
The goal of this proposal is to develop an atomic level understanding of the interface formation process between Al/Metal-oxide by combining spectroscopy (in-situ IR, XPS and LEIS), imaging (SEM, HRTEM) with DFT calculations for a variety of deposition methods. The novelty of the work stems from the preparation of model surfaces, from which detailed atomic information can be derived, and from the implementation of atomically precise deposition methods (e.g. ALD) in combination with nanopatterning processes to assess quantitatively the contribution of the interfacial layers for both the reaction kinetics and the stability at low temperature. The strength of the project is to bring a powerful multidisciplinary partnership, allowing the development of novel theoretical methods (A. Estève) coupled with extensive and unique in situ characterization methods (Y. Chabal) to address deposition/synthesis issues specifically associated with highly reactive materials. Atomic scale process simulation (A. Estève) will incorporate a novel accelerated Molecular Dynamics scheme (hyperthermal Kinetic Monte Carlo) into conventional Kinetic Monte Carlo to overcome issues associated with exothermic reactions. This will lay the foundation of a TCAD (Technology Computer Aided Design) dedicated to reactive Al/metal oxide nanolaminates synthesis. A second objective is to engineer a high-quality, ultra-thin and chemically-controlled Al2O3 interface layers in nanolaminated heterostructures combining ALD (Y. Chabal) with conventional PVD techniques (C. Rossi). Thermal characterization techniques (DTA, TGA, DSC), combustion tests combined with high resolution imaging and X ray diffraction (XRD) will permit to quantitatively evaluate the role of such interfaces in operating conditions (C. Rossi).
This project not only constitutes a transformative step towards the design of “tailored” reactive nanolaminated structures by interface optimization using “atomically precise technologies”, but also lays the foundation for a fundamental understanding of highly energetic materials.