Hooper, Joseph P.

This work is part of a large multi-university research initiative (MURI) between several universities. NPS will perform atomistic simulations to study growth of metalloid clusters inside metal/organic frameworks as an avenue to creating low-valence metal clusters of controlled size that could be used for fast-burning propellants or explosives. The overall MURI project summary is given below: We will develop a program to synthesize metalloid clusters and small metalloid nanoparticles (“nanoclusters”), assemble them into networks, and tune their properties by varying cluster size and network structure. Metalloid clusters, such as Al77[N(SiMe3)2]202-, have been of interest for years due to their potential use as energetic materials, catalysts, optical and magnetic compounds. The main impediment to studying and developing wide ranges of metalloid clusters has been the difficulty of preparing bulk quantities of these compounds and packaging them into useful forms. The metalloid cluster size regime (~100 - 200 atoms) is in between the more stable classes of molecular clusters and bulk nanoparticles, which makes their synthesis and isolation particularly challenging. Similarly, nanoclusters must be protected lest a substantial mass fraction of the particle oxidize. The primary goals of the program are to develop general protocols for metalloid cluster and nanocluster synthesis, develop a theoretical framework to understand and predict properties, and prepare and characterize a series of metalloid clusters and cluster network structures. We are particularly interested in the evolution of structures and properties of metalloid clusters as they transition from the molecular regime into the bulk regime by way of small, ligated nanoclusters. Such knowledge will provide the framework for targeting optimal size and composition regimes for future cluster based materials in specific applications. The team will target a selected series of main group metalloid clusters (Si, Mg, B, Ge, Sn), since these elements cross the metal-to-non-metal border and are likely to possess an interesting range of properties, as well as a selected group of transition metals (Fe, Co, Mn, Pt), because these bulk elements have important magnetic and catalytic properties. Metalloid clusters and cluster networks have a wide range of potential impacts on DoD capabilities, including use as energetic materials, obscurants, and catalysts in electrical generation and storage devices (fuel cells and batteries). The fundamental knowledge generated through the proposed work herein would help advance these goals
Physics
Office of Naval Research
Navy
2018