Reactive conversion of polycrystalline SnO₂ into single-crystal nanofiber arrays at low oxygen partial pressure

Abstract

Single-crystal SnO2 nanofibers have been formed from SnO2 polycrystals via reaction at low oxygen partial pressures. Polycrystalline SnO2 disks coated with Au nanoparticles were exposed to humid H2/N2 at 700 to 800 °C. Single-crystal SnO2 nanofibers formed beneath Au nanoparticles, with the nanofiber length oriented parallel to the [100] crystallographic direction of SnO2. Because this simple process does not require either a separate source of a Sn–O-bearing vapor species located upstream of the substrate or a temperature gradient, single-crystal nanofibers may be formed on large area SnO2-bearing substrates.

Growth of 1‐D TiO2 Nanowires on Ti and Ti Alloys by Oxidation

“…As oxygen from TiO 2 is taken out as H 2 O (g), Ti diffuses from the surface to the bulk [40]. We have also developed a method involving H 2 /N 2 heat treatment to grow nanofibers of SnO 2 in parts of the sample coated with gold, showing directional growth on grains with crystal facets [41]. The top end of each growing SnO 2 nanofiber contained a gold nanoparticle, with a distinct orientation relation detected at the Au/SnO 2 interface.…”

(Sensor Division Outstanding Achievement Award Presentation) Ceramic Gas Sensors to Oxide Nanostructures: Opportunities and Challenges

“…nanofibers on polycrystalline SnO2 in regions of the sample coated with gold, showing directional growth on grains with crystal facets [32]. 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 [33,34].…”

One-Dimensional Oxide Nanostructures Produced by Gas Phase Reaction

“…4 For this work, polycrystalline SnO 2 -based disks served as both the source material and the substrate for the growth of SnO 2 nanowires. The growth process consisted of depositing a thin layer of Au, a prominent catalyst in the VLS mechanism, onto the polycrystalline disks.…”

“…The substrates, bearing Au nanoparticles, were then heated to a temperature in the range of 700-800 • C under a controlled atmosphere and exposed to a humid H 2 bearing gas mixture for some time. 4 This process resulted in the formation of 100-200 nm diameter fibers. An increase in the exposure time of the substrate to the gas mixture resulted in an increase in the average fiber length which can be seen by comparing Figs.…”