Title

Organization of manganese oxide nanoparticles into structures and materials with multi-scale ordering

Date of Completion

January 2000

Keywords

Chemistry, Inorganic|Physics, Condensed Matter

Degree

Ph.D.

Abstract

The results described here for manganese oxide nanoparticles show formation of several systems as a function of time. Interactions with glass surfaces, confinement within a restricted geometry, and applied heat are all conditions which are favorable for the formation of ordered layered MnOx materials. These ordered materials span across multiple length scales from nm to cm and exist as films, fibers, and micropatterns. The ability to control the types and characteristics of the final product is a unique and remarkable feature of this system. Manganese oxide nanoparticles as colloidal solutions are prepared by reduction of the tetraalkylammonium permanganate with a solution of alcohol (2-butanol) and water. The colloids consist of disk-like lamellar slabs of manganese oxide that are dissociated in solution. XRD studies demonstrated long range order in films, fibers, and micropatterns. The highest d spacing corresponding to interlayer spacing ranged from 9 to 17 Å. XRD data were consistent with CdI2-type edge shared octahedra in expanded hexagonal layers of manganese oxide with tetraalkylammonium cations and water intercalated between the layers. ^ Lamellar manganese oxide films, micropatterns, and fibers can undergo quantitative and fast ion-exchange reactions in solution with inorganic and organic cations with retention of the layered structure. These materials can be thermally modified to produce OL and OMS phases, and provide templates for a variety of potential applications. ^