Synthesis of Tio 2 Meso-Structured Thin Films
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mesoporous thin films make it possible for applications as functional devices 4 -8 . The silicate mesoporous film can be controlled by the ratio of silica over surfactant to form lamellar, hexagonal, cubic and other phases by dip coating 7 or spontaneous formation at air-water interfaces 6 and spin coating 7 ,8 . This approach to meso-structured materials has been extended to non-silica oxides, especially transition-metal-oxides which might promise applications involving electron transfer and photocatalysts. TiO 2 is one of the most attractive materials in transition-metal-oxides group because of its wide application in photo-catalysis, solar cell and luminescence. J.K.Ying 9 , I.A.Aksay10 , and Zhou 11 reported the synthesis of hexagonal and lamellar phase mesoporous TiO 2 powder. But the synthesis of transition-metal-oxide meso-structure thin film hasn't reported. Here, we firstly report the synthesis of an oriented TiO 2 transition-metal-oxides meso-structured film, using a surfactant templating processing with spin coating method. We chose dodecyl phosphate (C12 PO) as a surfactant. We also tried other surfactants such as hexadecyltrimethyl-ammonium bromide(C 16 -TMA), and cetylamine (C1 6 NH2) etc. Only amorphous meso-structured TiO 2 thin film was obtained by C16-TMA and C16 NH2 just as reported 9- 11 .
209 Mat. Res. Soc. Symp. Proc. Vol. 576 01999 Materials Research Society
SYNTHESIS OF TiO2 MSTF TiO 2 meso-structure thin film was prepared as follow: Ti(OPri) 4 (TTIP) was mixed with acetyl acetone (AcAc) in a mol ratio 1:1 with stirring. Then 2-propanol was added to above mixture solution with stirring. Finally, required amount of the surfactant C 12 PO aqueous solution was dropped in. The reaction mixture was neutralized by adding dropwise a little NH 4 OH aqueous solution very carefully to keep pH value in the range of 6.0 to 7.0. The hybrid sol with different aging time at room temperature was used for the TiO 2 MSTF by a spin coating method.
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20 Fig. 1 X-ray diffraction pattern of TiO 2 MSTF
RESULTS AND DISCUSSION The X-ray diffraction pattern of the TiO 2 MSTF from 1 day aging of the hybrid sol is shown in Fig.1. The [100], [200] and [300] peaks of lamellar phase were observed with d spacing 37.8A, 18.8A and 12.6Ak respectively. Lamellar phase has been reported in mesoporous TiO 2 powder' 0 . The lamellar structure of C 12PO/TiO 2 MSTF collapsed after 2 hours heat treatment in 300°C. The XRD intensity of [100] peak decreases as increasing annealing temperature, but the peak's position almost keeps the same, which is different from that of the lamellar SiO 2 MSTF, where the [100] peak shifted to high degree side with increasing annealing temperature 1 2. Although the hexagonal phase has been observed in mesoporous TiO 2 powder 9 , we only get the lamellar phase in TiO 2 MSTF even changing the TTIP/C 12 P0 ratio in a wide range just as we did in phase controlled SiO 2 MSTF 8 .
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Fig.2 X-ray diffraction pattern of TiO 2 MSTF with different aging time, which shows t
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