Effect of substrate on the microstructure and morphology of Ag-TiO2 sol gel coating

Sim, Voon Yee (2015) Effect of substrate on the microstructure and morphology of Ag-TiO2 sol gel coating. Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

Silver titanium dioxide (Ag-TiO2) coatings obtained by a sol gel method were deposited on three substrates with different crystallinity : amorphous glass, single crystal silicon wafer (100) and polycrystal indium tin oxide (ITO) glass. First, titanium dioxide (TiO2) sol was synthesized in room temperature and acidic condition by hydrolysis of titanium tetraisopropoxide (TTiP) in ethanol, hydrochloric acid (HCL) and deionized (DI) water. Five layers of TiO2 coatings were deposited on all substrates using TiO2 sol by a dip coating process. Then, TiO2 coated substrate was dipped into pure silver nanoparticles solution to introduce antimicrobial effect. Sintering temperature was set at 500°C to produce small crystal size and more anatase phases. Physical observation and morphology of coating using scanning electron microscopy (SEM) had been conducted. SEM investigation revealed that the TiO2 coating deposited on amorphous glass and ITO glass substrates was not homogenous whilst silicon wafer substrate can formed a transparent and dense coating. On the other hand, Ag-TiO2 coating on three substrates was not transparent due to the presence of oxidized silver nanoparticles. The coatings were non homogenous. Silver nanoparticles did not embed into TiO2 coating and forming a layer on top of it. Fine and irregular shape of silver particles had found on the coating of glass substrate while silver flakes aggregated on coating surface of ITO glass and silicon wafer substrates. Additional characterization method should be conducted in future study to clarify the correlation between crystallinity of substrate and crystallite transformation of Ag-TiO2 coating.

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