The zirconia is one of the transition metal oxides with a wide band-gap, showing many good mechanical and physical properties. This study concentrates on the preparation of the polystyrene template and the characterization of the ordered mesoporous zirconia thus prepared. The polystyrene (PS) templates have been prepared by the emulsifier-free emulsion polymerization of styrene monomer (SM) in mixed solution of K2S2O8 and H2O, without any cross-linking agent. The PS spheres so prepared have diameters ranging from 50 ¡V 400 nm. These spheres are then arranged in array by sedimentation method; then the infiltration of
zirconia sol solution is followed. After the sol has been transformed to the gel, calcinations under high temperature are proceeded to remove the PS template to obtain the ordered mesoporous zirconia with various pore sizes. Doping of the zirconia also is conducted by applying an AgNO3 solution to the mesoporous zirconia. Results from SEM indicate that with a fixed ratio of K2S2O8/styrene = 5.98 wt¢H, the PS size decreases with the SM concentration; PS as small as 66 nm can be obtained when SM/H2O = 0.05¢H by volume. The PS spheres forms a hexagonal close packing when using a solution of H2O/ethanol = 3¡G7 by wt during sedimentation. Shrinkage ranging from 60 ¡V 80% of the original PS size happens when the PS template is removed from the calcined zirconia. Results from XRD indicate the same tetragonal crystalline structure of zirconia after calcinations at 500oC, regardless of the different pore sizes.
BET measurements show the specific surface area of the zirconia from 6.05 - 42.61m2/g. For Ag-doped zirconia under hydrogen atmosphere, it is found from EDS mapping that the AgNO3 can be reduced to the metallic silver without particles aggregation but random distribution on the pore walls or surfaces, while the tetragonal crystalline structure of zirconia remains unaltered.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0721108-141340 |
| Date | 21 July 2008 |
| Creators | Liu, Chao-Chia |
| Contributors | Wei-Hung Su, Tzu-Chien Hsu, Bing-Hwai Hwang, Hong-Yang Lu |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0721108-141340 |
| Rights | not_available, Copyright information available at source archive |
Page generated in 0.0015 seconds