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FIZIKA A 6 (1997) 2, 77-88
 
TRANSMISSION ELECTRON MICROSCOPY, X-RAY DIFFRACTION AND RAMAN
SCATTERING STUDIES OF NANOPHASE TiO2
ALEKSANDRA TURKOVĆa, ANĐELKA TONEJCb, STANKO
POPOVIĆa,b, PAVO DUBČEKa, MILE IVANDAa, SVETOZAR MUSIĆa
and MARIJAN GOTIĆa
aRuđer Bošković Institute, P. O. Box 1016, 10001 Zagreb,
Croatia
bDepartment of Physics, Faculty of Sciences, University of Zagreb, P. O. Box
162, 10001 Zagreb, Croatia
Received 17 January 1997
Revised manuscript received 27 March 1997
This paper is dedicated to Professor A. Bonefačić on the occasion
of his 70th birthday
Dye-sensitized solar cells differ from conventional semiconductor devices in that they
separate the function of light absorption from charge-carrier transport. The device is
based on a 10-mm-thick optically transparent film of titanium
dioxide (TiO2) particles of a few nanometers in size, coated with a monolayer
of charge-transfer dye to sensitize the film for light harvesting. In the present authors'
review, the principal role of the TiO2 photoanode is emphasized by a detailed
presentation of its characterization by different experimental methods, while the
photoelectric responses of the cells, a work which is still in progress, are indicated in
the references cited. Hydrolysis of Ti(IV)-isopropoxide in isopropanol by the addition of
water is a suitable chemical reaction for the production of nanosized TiO2. The
properties of nanosized TiO2 can be modified by the hydrolysis catalyst, pH of
the solution, temperature, presence of complexing ligand and the colloidal state of TiO2
precursor. In the present work, the microstructural properties of nanosized TiO2
were studied by HREM, ED, XRD, SAXS and Raman spectroscopy. HREM was used to determine
both grain and pore sizes. Electron diffraction and X-ray diffraction provided evidence of
nanocrystalline anatase and brookite phases. The grain sizes of the anatase and brookite
phases changed from (5±1) to (12±3)
nm with an increase of the treating temperature up to 773 K, as shown by XRD. An method of
determining nanosized TiO2 grain size based on low-frequency Raman scattering,
is presented.
UDC 538.975
PACS 68.55.Nq, 81.15.Lm
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