STRUCTURAL, OPTICAL AND GAS SENSING PROPERTIES OF ZnO, SnO2 AND ZTO NANOSTRUCTURES

Tetrapods, nanobelts and polyhedron-shape like zinc oxide (ZnO), tin dioxide (SnO2) nanostructures and ZnO/ZnSnO3/Zn2SnO4 (ZTO) composite functional semiconducting nanostructures have been synthesized successfully by the vapor-solid growth process. XRD analyses showed that ZnO with wurtzite, SnO2 with rutile and zinc stannate (ZnSnO3) and/or dizinc stannate (Zn2SnO4) with polyhedral crystal structure were condensed from the vapor phase when Zn and/or Sn metal powders individually or mixed were used as the starting materials. The driving forces for growth of these nanostructures were found to be vapor density, temperature, pressure and place of deposition from the source materials. Typically, the ZnO nanobelts have lengths of several hundred of nanometers and widths of about 10-15nm. The average particle size of SnO2 are in the range of about 10-20 nm. Uniform hexagonal-shaped crystals of ZnO/ZnSnO3/Zn2SnO4 composite in the range of 50-300nm as estimated from TEM images are observed. Based on the TEM, optical absorption and emission studies and the CO gas sensing characteristics of the prepared materials showed good crystal quality implying that the ZnO, SnO2 and ZnO/ZnSnO3/Zn2SnO4 nanostructures may suggest possible applications in optoelectronic devices and chemical gas sensors.