Hiroshi Hirashima
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-Ku, Yokohama 223-8522

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CRYSTALLIZATION BEHAVIOR AND MICROMORPHOLOGY OF SOL-GEL DERIVED MESOPOROUS NANO-PARTICLES TITANIA Tursiloadi, Silvester; Hirashima, Hiroshi; Yamanakaz, Yu
Jurnal Sains Materi Indonesia Vol 6, No 1: OKTOBER 2004
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (801.377 KB) | DOI: 10.17146/jsmi.2004.6.1.4913

Abstract

CRYSTALLIZATION BEHAVIOR AND MICROMORPHOLOGY OF SOL-GEL DERIVED MESOPOROUS NANO-PARTICLES TITANIA. In this work, effects of drying methods on the micro-morphology ofinesoporpous TiO2 prepared by the sol-gel method has been studied using transmission electron microscopy (TEM), X-ray diffraction analysis (XRD) and N2 gas adsorption. Mesoporous TiO2 consists of anatase nano-particles, about 5nm in diameter, have been obtained by hydrolysis of titanium alkoxide in a methanol solution and supercritical extraction in CO2 at 60°C and 22Mpa. XRD peaks ofrutile have been found after annealing at 600°C. The particle sizes of anatase and rutile are about 13 and 25nm in diameter, respectively. The surface morphology of Ti02 nano-particles has been discussed with the surface fractal dimensions estimated from the N2 gas adsorption isotherms.
BENZYLTRIMETHYLAMMONIUM CHLORIDE IMMERSION EFFECT ON PHYSICAL PROPERTIES OF TIO2 – AL203 Tursiloadi, Silvester; Hirashima, Hiroshi
Jurnal Sains Materi Indonesia Vol 5, No 2: FEBRUARI 2004
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (773.725 KB) | DOI: 10.17146/jusami.2004.5.2.5210

Abstract

BENZYLTRIMETHYLAMMONIUM CHLORIDE IMMERSION EFFECT ON PHYSICAL PROPERTIES OF TiO2 ? Al2O3. Mesoporous TiO2 - Al2O3 powders have potential applications in catalysts or support catalysts. A novel method to control pore size of sol--gel by a cationic surfactant benzyltrimethylammonium chloride (BTAC) Immersion was investigated. The gels of TiO2- Al2O3 in molar ratio of 0.2 of TiO2, and 0.8 of Al2O3 were prepared by hydrolysis of aluminium sec-butoxide, Al(OC4H9sec)3 and titanium isopropoxide Ti(OC3H7iso)4 in an n-propanol solution with acid catalyst. The structures and porosities of the modified TiO2-A|2O3 was depended on the dimensions of surfactant, as long as the calcination was carried out at 500? to avoid aggregation process during removal of excess BTAC. If the calcinations were carried out at 800? no significant change of the pore volume of modified samples was remarkably not observed, even though formation of TiO2 rutile has been taken place. It indicated that samples modi?cation by initial immersion of gel into BTAC may avoid the sintering. These results suggest that during the calcinations TiO2, was segregated from the Al2O3 particles to form nuclei of rutile and was crystallized prior to formation of ?- Al2O3. Therefore, the formation of rutile TiO2 induced the formation of ?- Al2O3.
THE STABILIZING OF ANATASE AEROGEL AT HIGH TEMPERATURE Tursiloadi, Silvester; Hirashima, Hiroshi
Indonesian Journal of Chemistry Vol 4, No 2 (2004)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (877.936 KB) | DOI: 10.22146/ijc.21863

Abstract

Stable anatase is attractive to its notable functions for photo catalysis and photon-electron transfer.   Stable anatase TiO­2 containing amorphous SiO2 aerogel was prepared by hydrolysis of Ti (OC3H7)4 and Si (OC3H7)4 in a 2-propanol solution with acid catalyst. The solvent in wet gels was supercritically extracted in CO2 at 60 oC and 22 Mpa. Thermal evolutions of the microstructure of the gels were evaluated by TGA-DTA, N2 adsorption and XRD. A stable anatase TiO2 containing amorphous SiO2 aerogel with a BET specific surface area of 365 m2/g and a total pore volume of 0.20 cm3/g was obtained as prepared condition. The anatase phase was stable after calcination up to 1000 oC, and BET specific surface area, total pore volume and average pore diameter did not change significantly after calcination up to 900 oC.
SOL-GEL PROCESS FOR THE MANUFACTURING OF TRANSLUCENT LEAD ZIRCONATE TITANATE GEL-MONOLITH Tursiloadi, Silvester; Imai, Hiroaki; Hirashima, Hiroshi
Jurnal Kimia Terapan Indonesia Vol 6, No 1-2 (1996)
Publisher : Research Center for Chemistry - LIPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (5234.829 KB) | DOI: 10.14203/jkti.v6i1-2.231

Abstract

Translucent Lead Zirconate Titanate (PZT) gel-monolith was prepared by partially hydrolyzing metal alkoxides solution which modified with acetylacetone(acacH). Metal alkoxides, lead di-i-propoxide, zirconium tetra-nbutoxide and titanium tetra-i-propoxide were used as starting materials. In Infrared spectra for the translucent monolithic gel after aging at room temperature for several days or drying at 90C for 18h, the most significant feature is the presence of band at around 1554 cm-1 which can be assigned to the v (C-O) and v (C-C) vibrati-ons of acetylacetanate group coordinated to the metal cations Ti and Zr. The diffraction peaks of PbO were found after heating at 300C for 2h. After heating at 450 C for 2 h, diffraction peaks of pyrochlore Pb2 Ti206 and perovskite PZT phase were observed. The diffraction peaks of PbO and pyrochlore phase disappeared after heating at 600C, and tetragonal perovskite phase was stable up to 1000 C. The diffraction peaks of perovskite phase were also found after heating at 430 for 24 h. The density of the compacted pulverizedgel after heating at 1000C for 30 min. was 6.9 g/cm3 , about 86% of the theoretical value.
PREPARATION OF LEAD ZIRCONATE TITANATE FILM BY SOL-GEL METHOD AND ITS CHARACTERIZATION Tursiloadi, Silvester; Imai, Hiroaki; Hirashima, Hiroshi
Jurnal Kimia Terapan Indonesia Vol 6, No 1-2 (1996)
Publisher : Research Center for Chemistry - LIPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (5139.688 KB) | DOI: 10.14203/jkti.v6i1-2.232

Abstract

A ferroelectric material film of Lead Zirconate Titanate, Pb(Zr,Ti)O3 (PZT), was produced by sol-gel method from alkoxide and acetate precursors in a normal propanol solvent system. The excess amount of Pb was 10 mole % more than stoichiometrically used for preparing the solution. The concentration of PZT in coating solution was 0.7 M, and pH of the solution was 4.5. The films was prepared by dip-coating onto slide glass, silica glass and Pt/Ti/SiO2/Si substrate. In order to avoid cracking TiO2 was coated on the glasses as a barrier layer. The asdried PZT film was amorphous from X-ray diffraction. The amount of pyrochlore and perovskite phase depended on the heating temperature and kind of barrier layer. Single perovskite phase was found for coated films on TiO2/SiO2 and Pt/Ti/SiO2/Si heated at 600 C or higher, but it was never found for coated films on SiO2 substrate without barrier layers. Crystallization of perovskite PZT film was retarded when deposited on amorphous substrates as compared to crystalline substrate. The coated film on Pt/Til/SiO2/Si was thicker and smaller in particle size than that of coated film on Ti02/SiO2. A columnar structure with a diameter around 6.5 nm, was observed and no boundary was observed between layers in 9 time dipcoated film on Pt/Ti/SiO2/Si.
LOW-TEMPERATURE SYNTHESIS OF LEAD ZIRCONATE TITANATE (PZT) POWDER FROM METAL ALKOXIDES Tursiloadi, Silvester; Imai, Hiroaki; Hirashima, Hiroshi
Jurnal Kimia Terapan Indonesia Vol 5, No 1 (1995)
Publisher : Research Center for Chemistry - LIPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4140.929 KB) | DOI: 10.14203/jkti.v5i1.239

Abstract

PZT powder precipitate has been prepared by hydrolyzing a mixture of lead di-i-propoxide, zirconium tetra-n-butoxide and titanium tetrai-propoxide. The crystallization process of the amorphous PZT was studied by means of X-ray diffraction analysis. It was found that the powder precipitate was still amorphous on heating until 400C for 2k As an intermediate product, metastable cubic Pb2Ti2O6 (pyrochlore phase) was found after heating at 450C for 2h. In addition to Pb2Ti206 peaks, the diffraction peaks of perovskite PZT phase were observed after heating at 430C for 24 h. After heating at 600 C for 2h, only diffraction peaks of tetragonal perovskite PZT phase were found. The lattice parameters of the tetragonal PZT have been obtained to be a=4.066 A c=4.196 A This tetragonal perovskite phase was stable on heating until 1000 "C. The density of the compacted powder precipitate after heating at 1000C (a relatively low temperature for the sintering of PZT) for 30 min. was 6.1 g/cm3, about 76% of the theoretical value.
PREPARATION AND CHARACTERIZATION OF POROUS ALUMINA-TITANIA AEROGEL VIA CO2 SUPERCRITICAL EXTRACTION Tursiloadi, Silvester; Imai, Hiroaki; Hirashima, Hiroshi
Indonesian Journal of Chemistry Vol 4, No 3 (2004)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (3518.277 KB) | DOI: 10.22146/ijc.21845

Abstract

Porous aerogel of titania-alumina were prepared by hydrolysis of metal alkoxides and supercritical extraction of the solvent.  Monolithic wet-gel of 0.2TiO2-0.8Al2O3, prepared by hydrolysis of metal alkoxides in alcoholic solutions, and the solvent in wet gel was supercritically extracted in CO2 at 60oC and 24Mpa for 2h. Thermal evolutions of the microstructure of the gel were evaluated by differential thermal analysis (TG-DTA), N2 adsorption, scanning electron microscopy and X-ray diffractometer. After calcination at 500oC, the specific surface area of the gel was more than 400m2g-1. The average pore radius of aerogel, about 8nm, was about 50% of that for alumina aerogel, but about 4 times larger than that of the xerogel.  The specific surface area of the aerogel was more than 200m2g-1 after calcination at 800oC. The pore size and pore volume of aerogel hardly decreased after calcinations at 800oC, although those values of the xerogel remarkably decreased after calcination up to 800oC. The thermal stability of the microstructure of porous titania-alumina is improved by supercritical extraction.   Keywords: Oxides, Sol-gel chemistry, X-ray diffraction, Infrared pectroscopy