Ceramics

Biography

Biography: Sheikh A Akbar

Abstract

Recent work in the author’s laboratory has led to the development of simple processes for the fabrication of ordered and self-assembled nanostructures by exploiting intrinsic material properties that are inexpensive, highly scalable and do not require use of lithography. These processes can be classified as “oxide nanostructures by materials design”. One process creates nanofiber arrays of single crystal TiO2 by gas phase reaction in a H2/N2 environment. As oxygen from TiO2 is taken out as H2O (g), Ti diffuses from the surface to the bulk resulting in fibers oriented along the <001> direction. Work on single crystal TiO2 shows that on Au-catalyzed (001) surface, oriented nano-fibers can be grown with <001> and <110> alignments using H2/N2 heat treatment. The same gas heat treatment was also used to grow nanofibers on polycrystalline SnO2 in regions of the sample coated with gold, showing directional growth on grains with crystal facets. We have also developed a process to create nanofibers of TiO2 on Ti metal and Ti alloys via oxidation under a limited supply of oxygen (~10s of ppm). Lately, we have succeeded in converting the 1-D TiO2 nano-fiber grown by thermal oxidation to nano-dendritic titanates by a hydrothermal treatment. The conversion of TiO2 to barium (and other) titanates is a path to synthesizing materials in a different class of functionality because of their piezoelectric and ferroelectric responses. We developed yet another interesting nano-structure (nanoislands and nanobars) during thermal annealing of an oxide (GDC) on top of another oxide (YSZ) substrate that self-assembles along the softest elastic direction of the substrate. What is common about these structures is that they are fabricated without the use of lithographic techniques and involves simple processes such as gas-phase reactions and stress-driven process. These nano-structures can be used as platforms for chemical sensing, photo catalysis, electro emission and biomedical applications. Pre-liminary results of some of these applications are presented.