AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Controlling Composition and Morphology of Mixed Oxide Thin Films Synthesized by Aerosol Chemical Vapor Deposition (ACVD) Process
TANDEEP CHADHA, Jiaxi Fang, Pratim Biswas, Washington University in St. Louis
Abstract Number: 344 Working Group: Nanoparticles and Materials Synthesis
Abstract Mixed oxides of the form Li$_(1+x)Mn$_(2-x)O$_4 and LiMn$_(2-x)Ni$_xO$_4 find application as cathodes in lithium ion batteries. Current synthesis methods involve multiple steps, first producing a nanoparticle powder, followed by coating onto a conductive substrate and then annealing. These processes offer less control over the morphology and crystallinity of the cathode active material. A single step process for the synthesis of nanostructured thin films would facilitate the synthesis of nanostructured cathodes directly on a conductive substrate without the use of any binding agent.
The ACVD process is a single step, low cost process for the synthesis of nanostructured thin films. This process has been successfully demonstrated for the synthesis of metal oxides such as TiO$_2 and NiO with dense, single crystal columnar, granular and branched morphologies (An et al. 2010). The existing ACVD process involves decomposition of a metal organic precursor in the reactor to yield metal oxide molecules which by homogenous nucleation yield particles. These particles deposit onto a heated substrate where they sinter to form thin films of different morphologies. The synthesis of mixed oxide thin films would involve heterogeneous nucleation of multi component metal oxides to yield mixed oxide particles. This work focuses on controlling the composition and morphology of mixed oxide thin films synthesized by the ACVD process. Control over the characteristic times and the reaction rates was used to control the morphology and the stoichiometry of the synthesized thin films. The surface morphology of the films was characterized by scanning electron microscopy and the crystal structure was examined by x-ray diffraction analysis. X-ray photoelectron spectroscopy was used to probe the chemical composition of the films. The role of the reaction kinetics and thermodynamics in controlling the stoichiometry of the particle and the composition of the film will be presented.