• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.87-89
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• 1997

The BaTiO$_3$ fine powder was prepared by hydrthermal method using titanium tetrahydoxide (Ti(OH)$_4$) and barium dihydroxide (Ba(OH)$_2$.8$H_2O$) as raw materials. The fine powder was obtained at temperatures as low as 160 to 185$^{\circ}C$. The properties of the BaTiO$_3$ powder were studied as a function of various parameters (reaction temperature, reaction time, Ba/Ti=ratio, etc). The average particle size of the BaTiO$_3$ increased with increasing reaction temperature. After hydrothermal treatment at 17$0^{\circ}C$ for 8 h, the average particle size of the BaTiO$_3$ powder was about 30 nm and the particle size distribution was narrow.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.37-44
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• 1995

TiO2 fine powders were synthesized using oxygenolysis and hydrolysis reaction of TiCl4 vapor in gas phase. The TiO2 powder synthesized showed morphological differences depending on reaction system as follows: TiCl4-O2 reaction system produced the monosized particles having polyhedral shape with well-defined crystal planes and the particles did not agglomerate into secondary particles. TiCl4-H2O reaction system, whereas, produced the spherical secondary particles which consisted of fine primary particles. Other powder characteristics such as particle size, impurity content and rutile content are also reported in this study.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.128-130
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• 2008

One of methods to increase the efficiency of a dye-sensitized solar cell(DSC) is the effective usage of the incident light. It can be controlled by using a light scattering layer. The light scattering effect makes that the optical path length of incident light to DSC increases. And then, the photocurrent and the efficiency is increased because of the increase of dye adsorption and the abundant amount of the light. In this study, we apply the light scattering layer to DSC by using two $TiO_2$ pastes that have different particle sizes. As a result, the photocurrent increases and the total efficiency is also increases in the case of using large-sized $TiO_2$ particle as the light scattering layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.247-252
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• 2003

In this paper, we made four types of metal particle $Al_2$O$_3$ barrier reactors with and without dielectric of BaTiO$_3$ between metal particle and $Al_2$O$_3$ barrier to investigate NOx removal characteristic and the effect of dielectric on Nox removal. And Nox removal rate is measured when sludge pellets are put at down stream of plasma reactor. Nox removal rate in the reactor with $Al_2$O$_3$ barrier is much better than that in the reactor without $Al_2$O$_3$ barrier, Nox removal rate is not so good in metal particle-Al$_2$O$_3$ barrier reactor with BaTiO$_3$ between metal particle and $Al_2$O$_3$ barrier, however, Nox removal rate is about 40% in metal particle-Al$_2$O$_3$ barrier reactor with TiO$_2$. The most of NO is conversed to NO$_2$ in these kind of reactor. When sludge pellets are put at down stream of plasma reactor, Nox removal rate is greatly improved up to 90%. It indicates that sludge pellets have great effect on the NO$_2$ removal and the improvement of Nox removal rate, however, dielectric materials between metal particle and $Al_2$O$_3$ barrier have not effect. Organic materials included in sludge may react with NO$_2$ and ozone so that Nox removal rate is greatly improved.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.315-320
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• 1988

The Nb doped BaTiO3 was synthesized by coprecipitation method using H2O2 media in region from pH 8 to pH 11. The powder prepared by using this method was crystallized at about 20$0^{\circ}C$ and average particle size was controlled by heat treatment. Because of preparation having fine particle and relatively narrow particle size distribution, high performance PTC device was made of these precipitated powders.

• Journal of Powder Materials
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• v.10 no.2
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• pp.123-128
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• 2003

$TiO_2$ nanopowder was synthesized by chemical vapor condensation (CVC) process and its photocatalytic property depending on microstructure was considered in terns of decomposition rate of organic compound. In order to control microstructure of $TiO_2$ nanopowder such as particle size and degree of agglomeration, precursor flow rate representing number concentration was changed as a process variable. In TEM observation, spherical $TiO_2$ nanoparticles with average size of 20 nm showed gradual increases in particle size and degree of agglomeration with increase of precursor flow rate. Also decomposition rate of organic compound increased with decreasing precursor flow rate. Thus, it was concluded that photocatalytic property was enhanced by targe surface area of disperse $TiO_2$ nanoparticles synthesized at lower precursor flow rate condition in CVC process.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2348-2353
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• 2007

In this work, combustion-synthesized $TiO_2$ nanoparticles were used for the photocatalytic degradation of methylene blue with UV light irradiation. Also the results were compared with those of commercial $TiO_2$ nanoparticles (Degussa, P-25). Particle characteristics of the two were analyzed thru the SEM, TEM, and XRD. In spite of the lower specific surface area than that of P-25, the $TiO_2$ nanoparticles formed in this study showed the relatively good ability to degrade the concentration of the organics.

• 연구논문집
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• s.33
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• pp.123-135
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• 2003

Using the residence time calculated by computer simulation for temperature and gas velocity distribution in CVC reactor, the kinetics on the formation of $TiO_2$ nano powder was analyzed for coagulation process, After abrupt increase of particle size at initial growth stage (< 0.2 $\mus$ ), the particle grew in proportion of cubic root to time. The numerically calculated particle sizes well agreed with the experimental results. However, the coarse rutile $TiO_2$ powders having the particle size of over 40 nm were formed on the surface of quratz rod in the reactor. it is thought that the fine anatase particles condensed on quratz rod were sintered in a heated CVC reactor to grow and transform to coarse rutile phase, and the critical size for phase transformation anstase-to-rutile was around 25 nm tn this study.

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.691-697
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• 1989

Fine TiO2 and BaTiO3 powders having spherical particles were synthesized by ultrasonic spray pyrolysis of alcoholic solution of metal alkoxide in an electric furnace heated at 400-90$0^{\circ}C$. Microstructure and composition of particles synthesized were observed by TEM and XRD respectively. Spectific surface area of powders synthesized was examined through BET specific surface area measurement. TEM observation revealed that the particle size did not change irrespective of pyrolysis temperature but decreased according to the increase of concentration and spherical particle was consisted of primary particles of about 0.02${\mu}{\textrm}{m}$. As for BaTiO3 powder, the ratio of Ti/Ba was 0.987 by EDX analysis.

• Journal of the Korean Ceramic Society
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• v.29 no.9
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• pp.739-749
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• 1992

The sols prepared by dialyzing solutions, in which the hydrolyzed precipitates of TEOT or directly Ti(OC3H7)4 were resolved, were the nanoparticulate sol with the average particle size less than 7 nm and the anatase crystal phase. In the pH range of 1.5 to 2.9, the particle size of the nanoparticulate TiO2 sols (0.09 mol/ι) increased gradually upto 15 nm~26nm with the increase of pH in the initial aging state but the sols were transparent all the time, and stable without growin any more after 30 days. When the slipcasted porous alumina tubes were coated by the sol-gel dipping method, the minimum particle size and the aging time for forming the coated gel layer at the given pH were optimized. For obtaining the very thin crack-free and reproducible membrane coating, the use of a nanoparticulate TiO2 sol (0.09 mol/ι) aged for about 30 dyas at pH=2.0 was found to be the best.