Annual Report 2012 - Latvijas Universitātes Cietvielu fizikas institūts

Modified yarn strength decreases by 30%, which correlated with the moisture content
(6-12 %wt). Relative strength at 280 O C yarn with active particles respect to unmodified
increased in the direction Cu, Cu 2 O and CuO (fig.4; Fig.5).
Fig. 4. Breaking load, 240 o C
Fig. 5. Breaking load, 280 o C
PREPARATION OF TiO 2 THIN FILMS BY PARTICULATE
SOL-ELECTROPHORETIC DEPOSITION
G.Bajars, I.Liepina, A. Lusis, J.Gabrusenoks, E. Pentjuss
Titanium dioxide thin films have been extensively studied because of their
excellent properties for photocatalysis, gas sensors, ultrafiltration membranes, selfcleaning
coatings, solar cells and photovoltaic applications. Many efforts have been
made to improve their properties by preparing porous films with high surface area.
There are a wide variety of preparation methods for TiO 2 thin films, e.g. sol-gel, doctor
blade, spin coating, chemical vapor and sputter deposition. In this study nanocrystalline
TiO 2 thin films have been prepared by sol-electrophoretic deposition process.
The first step was the preparation of TiO 2 sol. Titanium tetra-iso-butoxide
(TTIB) was used as a precursor, hydrochloric acid as a catalyst for the peptization and
deionized water as a dispersion media. A water-acid mixture was stabilized at 50 °C
with continuous stirring. An appropriate amount of TTIB was added next forming the
white precipitate that gradually peptized forming a clear sol.
For the electrophoresis growth, the Pt anode and cathode are placed parallel in an
TiO 2 sol with a distance 1 cm in between. The cathodes used were metallic Cu and Ti,
thin Pt layer on silicon, transparent indium tin oxide (ITO) on glass. A constant voltage
of 0.5 – 0.6 V was applied by a dc power supply between the electrodes and held for 1 –
3 h. The as-deposited thin films were first dried at 100 °C for 24 h and then heated at a
rate of 10 °C/min and were finally annealed at 500 °C for 2 h.
Obtained TiO 2 thin films were characterized by phase composition, morphology
and their microstructures using X-ray diffraction, Raman spectroscopy, as well as
transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The
optical properties of TiO 2 thin films were investigate by analyzing I – V curves. The
possible correlations between the optical and structural properties of thin films are
discussed.
TiO2 thin films have been obtained by a sol-electrophoretic deposition method
on metallic Ti and Pt substrates. X-ray diffraction, Raman spectroscopy and scanning
electron microscopy were used to investigate the structure and morphology of plated
materials. Annealed TiO2 films mainly are formed in anatase structure with different
morphology depending on substrate material. Light induced potential measurements
indicate that the morphology substantially have an impact on photoactivity of TiO2 thin
films.
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