Growth and Characterization of ZnO, SnO2 and ZnO/SnO2 Nanostructures from the Vapor Phase.

Fouad, O. A.; Glaspell, G.; El-Shall, M. S. Central
Metallurgical Research and Development Institute (CMRDI), Cairo,
Egypt. Topics in Catalysis (2008), 47(1-2), 84-96. Publisher:
Springer, CODEN: TOCAFI ISSN: 1022-5528. Journal written in
English. AN 2008:340240 CAPLUS
Abstract
Zinc oxide (ZnO), tin dioxide (SnO2) and compds. ZnO/SnO2 (ZTO)
nanostructures have been synthesized successfully from the vapor phase
without a catalyst using three different approaches. XRD analyses
showed that ZnO with a wurtzite crystal structure, SnO2 with a rutile
crystal structure and zinc stannate (ZnSnO3) and/or dizinc stannate
(Zn2SnO4) were condensed from the vapor phase when Zn and/or Sn metal
powders or their oxides individually or mixed were used as the starting
materials. The formation of either zinc or dizinc stannate was
controlled by the Zn/Sn ratio and growth technique. SEM and TEM
investigations showed that ZnO grew mainly in the form of wires, rods
and belts. These are believed to be originated from the common tetrapod
structure of ZnO. While SnO2 grew in the form of tetragonal rods with
rectangle-like cross section and nanoparticles, ZTO grew in the form of
nanobelts. The final length, width and thickness were as low as 40, 10
and 5 nm, resp. The driving forces for growth of nanowires, nanorods,
nanobelts, and nanoparticles were found to be vapor d. or supersatn.,
temp., pressure and location of deposition from the source materials.
The optical absorbance and photoluminescence spectra of all samples
showed excitonic character at room temp. implying good crystal quality,
and high photocurrent properties suggesting possible applications in
nanoscaled functional devices such as optoelectronics and gas sensors.