Pennsylvania State University Professor A. Welford Castleman is researching superatoms as building blocks of new materials.
The electronic structure of small clusters of free-electron metallic and metalloid atoms is fundamentally different from the bulk. This gives unique “superatom” bonding properties to these clusters that resemble atomic bonding, but are distinctly different in character from any of the elements, which could result in novel properties for assembled solids formed of these clusters. The objectives of this project is to synthesize atomic clusters of tailored composition, structure, and size; and self-assemble them into condensed films and solids at the micrometer length scale that retain the distinct properties of the clusters.
The electronic structure of small clusters of free-electron metallic and metalloid atoms is fundamentally different from the bulk. This gives unique “superatom” bonding properties to these clusters that resemble atomic bonding, but are distinctly different in character from any of the elements, which could result in novel properties for assembled solids formed of these clusters. The objectives of this project is to synthesize atomic clusters of tailored composition, structure, and size; and self-assemble them into condensed films and solids at the micrometer length scale that retain the distinct properties of the clusters.
Once assembled into solids, the objective is to characterize the mechanical and electro-optical properties of the films and solids, and compare them to the current theoretical understanding of these systems. This should validate the current theoretical understanding and lead to sufficient model fidelity to begin activities on the exploration of devices based on cluster materials. Exploration of these materials is only just beginning and, aside from the C60-based materials, assembled cluster solids at this scale are unknown.
Potential properties include:
• Switchable band-gap materials where an external field adjusts the optical and electronic properties;
• High hardness materials that take advantage of strong inter-cluster bonding and large periodicity to inhibit plasticity;
• Efficient Terahertz-band emitters and detectors.
The investigation is noted in 2009 ARO in Review, a U.S. Army Research Office publication of on-going materials research for military and civilian applications sponsored by the ARO.
