Accession Number : ADA329756

Title :   Clusters of Transition Metal Compounds: Building Blocks of New Materials.

Descriptive Note : Final technical rept. 1 Apr 94-31 May 97,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF CHEMISTRY

Personal Author(s) : Castleman, A. W., Jr

PDF Url : ADA329756

Report Date : 30 MAY 1997

Pagination or Media Count : 34

Abstract : One of the great challenges facing the materials field is developing suitable methods for designing new materials with chosen properties. Assembling ones from clusters, i.e., producing nanostructure or cluster assembled materials, is a promising approach that we are exploring. The research program commenced April 1,1994, with work devoted to an investigation of Met-Cars and related small metal compound clusters. During the course of this study we found that binary metal Met-Cars, even comprised of metals that do not yield the pure Met-Car structure, can be formed. This gives promise of attaining the ability to tailor the design of materials of specific desired properties. In related studies, we found that Met-Cars undergo a substantially delayed ionization mechanism analogous to thermionic emission, which further points to their unique electronic properties. During the course of the program, we made valuable progress in elucidating mechanisms of formation and characterizing the bonding and structure of Met-Cars. Investigations of collision-induced dissociation revealed the unique stability of the MaCi2 stoichiometry and provided new evidence for the nature of the bonding of the lattice cage. An investigation of Met-Car adducts also has provided further understanding of the stability and bonding of various ligation complexes, and showed an analogy between their "adsorption to Met-Cars and to their bonding with certain metal surfaces. These findings are yielding new information about Met-Cars, as well as the nature of new complexes which can be formed from these nanophase materials. In addition to studies devoted to determining their mechanisms of formation and their physical and chemical properties in gas-phase experiments, effort has been underway to develop efficient methods of synthesizing the bulk materials.

Descriptors :   *CLUSTERING, METALS, SYNTHESIS, CHEMICAL PROPERTIES, PHYSICAL PROPERTIES, MATERIALS, ELECTROMAGNETIC PROPERTIES, EFFICIENCY, MODULAR CONSTRUCTION, VAPOR PHASES, PHASE, BULK MATERIALS, SURFACES, BONDING, TRANSITION METAL COMPOUNDS, THERMIONIC EMISSION.

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE