Multi-elements doped TiO2 was prepared as a new photocatalyst in order to decrease the band gap of TiO2 by sol-gel process which can provide the large active sites of TiO2. Multi-elements were doped by using a single precursor, tetraethylammonium tetrafluoroborate (TEATFB). By the benefit of large specific surface area of TiO2 prepared by sol-gel process, catalysts showed initial fast removal of dye. The photoactivity showed that the doped catalysts significantly promote the light reactivity than undoped TiO2. The commendable photoactivity of prepared catalysts is predominantly attributable to the doping of anions which may reduce the band gap.

본 연구에서 졸-겔 방법에 의하여 나노 기공을 가지는 세라믹막을 제조하여 단일 조성의 헬륨과 질소를 가지고 기체투과 실험을 수행하였다. 기공 크기 0.1 μm, 기공율 32%의 평막형 α-Al2O3 지지체를 제조하였으며, 지지체를 담지하여 코팅하는 방법으로 4nm의 기공 크기를 가지는 γ-Al2O3 중간층을 제조하였다. 실리카 졸은 TEOS의 산 촉매 가수분해와 축중합반응을 통하여 합성하였다. 막은 딥코팅과 소결과정을 거쳐 제조되었다. 졸-겔 법에 의해 합성된 세라믹 막을 통한 헬륨, 질소 투과 실험은 기체의 투과 특성을 파악하기 위하여 시행하였다. 질소에 대한 헬륨의 선택도는 100∼160 정도였으며 헬륨의 투과도는 303∼363 K의 온도 범위에서 10 -7 mol/m 2 ⋅s⋅Pa 정도였다.

xTiO2-ySiO2 system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area were measured. Considering the efficiency of the ethanol and phenol degradation using the catalyst, the conclusions were obtained as follows: By means of X-ray analysis of xTiO2-ySiO2 powder that is obtained from Titanium and Silicon alkoxide by sol-gel process, it is shown that crystal structure of anatase type is a dominating structure and, on the other hand, the structure of rutile also partly exists. The increase of SiO2 contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. It is shown that more than 90% of ethanol and phenol are degraded when reaction time is about three and an hours, and the maximum degradation rate of ethanol and phenol is shown in 60TiO2-40SiO2 catalyst.

BaTiO3 powders were prepared by sol-gel method from different concentration of KOH aqueous solution and Ba/Ti molar ratio. Particle shape, size and crystal structure of prepared BaTiO3 powders were analyzed by SEM, XRD, and FT-IR. As the result of KOH concentration changing, spherical particles were obtained by condition more than 3 M and particle size decreased as concentration increasing. Different appearance showed between dried and sintered powders against changing of Ba/Ti molar ratio. In case of dried powders, the crystallinity decreased as molar ratio increasing. On the other hand, increased as molar ratio increasing in case of sintered powders.

상변환과 졸-겔 반응을 동시에 행하는 새로운 제막법으로 나노크기의 ZrO2 입자가 함유된 비대칭형 PES-ZrO2 복합 막을 제조하였다. PES-ZrO2 복합 막 제조의 최적 제막 조건을 복합 막에의 인 흡착실험을 수행하여 인 흡착량이 최대가 되는 조건으로서 결정하였는바, 최적 제막 조건은 캐스팅 용액에 1 mL의 PES 당 0.15 mL의 Zr(PrO)4 첨가 및 비용매 1 L에 1 mL Zr(PrO)4 당 30 mL의 HNO3 촉매를 첨가했을 때 이었다. 복합 막의 단면 구조, 막성능 및 ZrO2 입자 함유량 변화를 SEM, 순수투과량, TGA, ICP, XRD 및 접촉각 측정을 통해 결정하였는바, 캐스팅 용액에의 Zr(PrO)4 첨가량이 증가할수록 순수 투과량이 증가하며, ZrO2 입자 함유량은 1 mL의 PES 당 0.15 mL의 Zr(PrO)4 첨가했을 때 최대가 되었다. 복합 막의 표면 특성을 친수성으로 개선하기 위하여 인산처리를 하였으며, 인산처리 전후(前後)의 두 종류 PES-ZrO2 복합 막을 대상으로 한 BSA 용액의 dead-end 한외여과 실험을 수행하여 막오염 형성의 억제 정도를 평가한 결과 인산처리 시킨 복합 막의 경우 투과량과 BSA 배제도 모두 약 40% 정도 증가하였는데 이는 복합 막을 인산처리 시킴으로서 막특성이 친수화 되었기 때문이다.

Field emission display(FED) is actively investigated in view of the development of full color flat-panel display, which can replace some cathode-ray tube(CRT). Thus, the development of new phosphors appropriate for FED is urgently needed and has been actively investigated. In this work, SrTiO3:Pr3+ phosphor was prepared by sol-gel method and the coating was applied by sol-gel method combined with sonication on these phosphor's surface into diluted precursor solution. It was found that very fine particles of coating material were formed on phosphor's surface. The luminescent intensity of SrTiO3:Pr3+ phosphor coated with SiO2 and Al2O3 was considerably increased without any noticeable change in color chromaticity. The optimum concentration of coating material was found to be 1wt% and the optimum pH value of the solution was 10.

Synthesis of zinc oxide nanorods, sheets and flower like structure were done by the sol-gel method using zinc acetate dihydrate and sodium hydroxide at with 12 hours refluxing time nanorods, in case of as synthesized powder, with diameter of 20-60nm. Annealing at higher temperature (300 and ,) in air ambient changes the morphology to sheet and flower like structure. The standard peak of zinc oxide was observed in IR at . The UV-VIS spectroscopy of zinc oxide shows a characteristic peak at 375nm.

In the present study, silver-doped antibacterial hydroxyapatites were successfully prepared by the sol-gel method. For the starting solution, the molar ratio of was set to 0.075:0.045:20:0.135; was added to a ratio of Ag to total cation concentration of . The prepared sol was dried at for 48h and heat-treated at for 2h to obtain particles in the 200-500nm size range. The product from the synthesis of silver-doped hydroxyapatite was investigated through X-ray diffraction experiments and scanning electron microscopy. The product showed high antibacterial properties, with a disinfection ratio of Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25922) over as calculated from an antimicrobial effects evaluation by the shake flask method.

An aqueous solution of a commercial liquid synthetic detergent for kitchen use was photodecomposed in the presence of titanium dioxides powder under an atmosphere of air at room temperature. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio(H2O/titanium iso-propoxide) and calcined at 500℃. All titanium dioxides were characterized by XRD, BET surface area analyzer and UV-VIS spectrometer. The surface area of titanium dioxides prepared at R ratio=6 appeared higher volume about 20% than commercial TiO2 catalysts. XRD patterns of titania particles were observed mixing phase together with rutile and anatase type. Titanium dioxides prepared by sol-gel method show higher activity about 6% than commercial TiO2 catalysts on the photocatalytic degradation of a commercial liquid synthetic detergent for kitchen. The concentration of the detergent decreased to about 90% of its initial value at illumination times of 2 hour. Illumination for 30 minutes decreased the concentration of oxygen to about one-fifth of the initial value.

고온에서 수소 분리 회수를 목적으로 silica/alumina 복합 막을 합성하였다. 막의 선택 투과 성능을 향상시키기 위해, sol-gel법에 의한 silica 및 alumina층을 중간층으로 도입하고, 그 위에 강제유동 CVD법에 의한 silica를 합성하였다. Sol-gel법에 의해 alpha-alumina tube에 합성한 gamma-alumina 및 silica 막은 Knudsen 확산 영역의 많은 mesopore를 포함하고 있어서 수소 선택 분리 막으로는 적합하지 못했다. 하지만, sol-gel법에 의해 합성한 silica/gamma-alumina층에 강제유동 CVD법으로 silica를 합성한 결과, 질소 투과 영역의 세공이 완전히 제거되어, 높은 수소 선택성을 가지는 복합 막이 형성되었다. 그 막은 온도에 따라 수소 투과 속도가 증가하여 450℃에서 5.57times10-8molm2sLPa1의 수소 투과 속도와, 9.52 kJ/mol의 활성화 에너지를 나타냈다. 분자체 효과에 의해 질소 투과가 완전히 배제되고, 수소만 선택적으로 투과되는 silica/alumina 복합막이 성공적으로 합성된다.

A modification of the sol-gel method to obtain phase pure superconducting oxides is described. The method starts from organic salts of yttrium, barium and copper, such as acetates, and avoids the sudden and uncontrollable decomposition of the organic fraction which occurs if nitrates are used as starting materials. The aqueous solution obtained with citric acid in an alkaline medium is concentrated under vacuum. The solid so prepared is decomposed at about 300℃ thus giving an oxide precursor containing well dispersed yttrium, barium and copper. Pyrolysis at 850 - 920℃ followed by oxygen annealing gives the superconducting orthorhombic 123 phase. The results of TGA/DTA of the precursor, as well as XRD, electrical and magnetic property measurements on the pyrolysis products are presented and discussed.

Transparent films were prepared using the sol-gel process by mixing TEOS with PVA solution that was solved in EtOH and distilled water homogeneously. HCl, CH3COOH and NH4OH were used as catalysts of the sol-gel process, and for improving the flexibility of films glycerol was used as plasticizer. In case of each catalyst, transparency and tensile strength were increased, and glass transition temperature (Tg) was shifted to higher temperature with increasing TEOS ratio. Also, in case of adding the plasticizer, the flexibility of films was increased. On the contrary, transparency, thermal stability and tensile strength were decreased with increasing HCl and NH4OH ratio. Also, the range of being made of film type was expanded when CH3COOH was used than HCl and NH4OH.