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Willemite (Zn2SiO4) is a compound of zinc orthosilicate with rhombohedral crystal structure. Willemite shimmers green light under shortwave ultraviolet exposures which applicable for green phosphor host in flat panel display. In this final project we synthesize willemite powder by sol-gel method.<...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/11077 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Willemite (Zn2SiO4) is a compound of zinc orthosilicate with rhombohedral crystal structure. Willemite shimmers green light under shortwave ultraviolet exposures which applicable for green phosphor host in flat panel display. In this final project we synthesize willemite powder by sol-gel method.<p> <br />
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It was shown that willemite crystal was completely formed at 700 degrees C with excess silica in the form of cristobalite. Green sample of willemite was synthesized by mixing tetratehoxysilane (TEOS) and zinc acetate with molar ratio of 1:2. 21 % ammonium hydroxide was added to form gel, which subsequently washed with DI water to obtain white powder. This green powder was characterized using Fourier Transform Infra Red (FTIR) to reveal chemical bonding. The samples were calcined at temperature 600 degrees C, 700 degrees C, 800 degrees C and 900 degrees C for two hours. The degree of crystallization was examined using Thermogravimetry Analysis/Differential Thermal Analysis (TG/DTA) and X-Ray Diffraction (XRD), while the surface morphology was characterized using Scanning Electron Microscope (SEM).<p> <br />
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XRD result showed that willemite was formed by calcination at 700 degrees C for two hours. Instead of willemite, sample contained cristobalite as undesired product of unstoichiometric reaction. |
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