• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.498-504
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• 2011

We examined the microstructure and optical properties of crystallized ~30 nm-ZnO/~10 nm amorphous $TiO_2$ nano bilayered films as nano electrodes were deposited at extremely low substrate temperatures of $150-210^{\circ}C$. The bilayered films were deposited on silicon substrates with 10 cm diameters by ALD (atomic layer deposition) using DEZn (diethyl zinc(Zn(C2H5)2)) and TDMAT (tetrakis dimethyl-amid $titanium(Ti(N(CH_3)_2)_4)$ as the ZnO and $TiO_2$ precursors, respectively, and $H_2O$ as the oxidant. The microstructure, phase, and optical properties of the bilayered films were examined by FE-SEM, TEM, XRD, AES, and UV-VIS-NIR spectroscopy. FE-SEM and TEM showed that all bilayered films were deposited very uniformly and showed crystallized ZnO and amorphous $TiO_2$ layers. AES depth profiling showed that the ZnO and $TiO_2$ films had a stoichiometric composition of 1:1 and 1:2, respectively. These bilayered films have optical absorption properties in a wide range of ultraviolet wavelengths, 250-390 nm, whereas the single ZnO and $TiO_2$ films showed an absorption range of 350-380nm.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1019-1023
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• 1996

The dielectric properties at microwave frequencies of B site complex perovskite La(Zn1/2Ti1/2)O3 which has +3 ion in A site were investigated. maximum Q*F value of the specimens was 59000 dielectric constant 34, temperature coefficient of resonant frequency -52 ppm/$^{\circ}C$. XRD pattern of the sintered specimen shows (111) ssuperlattice reflection which indicates Zn and Ti cation ordering.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.963-967
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• 2001

The effects of the sintering additives such as Bi$_2$O$_3$and V$_2$O$_{5}$ on the microwave dielectric and sintering properties of ZnTiO$_3$system were investigated. Densities of >97% of the theoretical densities have been attained for ZnTiO$_3$at the sintering temperature range of 870~90$0^{\circ}C$ with Bi$_2$O$_3$and V$_2$O$_{5}$ additions of $_3$were obtained with 0.6wt% Bi$_2$O$_3$and 0.5wt% V$_2$O$_{5}$; Qxf$_{o}$ = 48,400 GHz, $\varepsilon$$_{r}$ = 22, and $\tau$$_{f}$ = -43 PPm/$^{\circ}C$. In order to improve temperature coefficient of resonance frequency, TiO$_2$was added to the above system. The optimum amount of TiO$_2$was 15mo1% when sintered at 87$0^{\circ}C$, at which we could obtain following results ; Qxf$_{o}$ = 44,700 GHz, $\varepsilon$$_{r}$ = 26, and $\tau$$_{f}$ = 0 ppm/$^{\circ}C$.EX>.>.EX>.>.>.EX>.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.30-36
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• 2002

The effects of the sintering additives such as B $i_2$ $O_3$ and $V_2$ $O_{5}$ on the microwave dielectric and sintering properties of ZnTi $O_3$ system were investigated. Highly dense samples were obtained for ZnTi $O_3$ at the sintering temperature range of 870~90$0^{\circ}C$ with B $i_2$ $O_3$ and $V_2$ $O_{5}$ additions of <1 wt.%, respectively. The microwave dielectric properties of ZnTi $O_3$ with 0.6 wt.% B $i_2$ $O_3$ and 0.5 wt.% $V_2$ $O_{5}$ were as follows: Qx $f_{o}$ = 48,400 GHz, $\varepsilon$$_{r}$= 22, and $\tau$$_{f}$ = -43 ppm/$^{\circ}C$. In order to improve temperature coefficient of resonant frequency, Ti $O_2$ was added to the abode system. The optimum amount of Ti $O_2$was 15 mol.% when sintered at 87$0^{\circ}C$, at which Ive could obtain following results: Qx $f_{O}$ = 44,700GHz, $\varepsilon$$_{r}$ = 26, and $\tau$$_{f}$ = 0 PPm/$^{\circ}C$.>.EX>.>.>.EX>.>.>.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.234-238
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• 1987

In this paper, the used specimen composition was added basic additives ($Bi_2O_3\;lmol%$, $Sb_2O_3\;lmol%$, CoO 0.5 mol%, MnO 0.5mol%) to ZnO powder, and $TiO_2$ (1,2,3,4 mol%) to the above basic composition. It appears that there are four regions of conduction current depended upon the strength of the applied electric field ; Ohimic region, Poole-Frenkel region, Schottky region and Tunneling region. Increasing of $TiO_2mol%$, the breakdown voltages of ZnO ceramic varistors are decreased. The decrease of breakdown voltages was explained with the decrease of potential barrier height. Moreover, V-I characteristics with temperature dependence are decreased with increasing of $TiO_2mol%$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.107-116
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• 1991

Fine $PbTiO_3$ Particles were synthesized from the $Pb(NO_3)_2$and $TiO(NO_3)_2$ solution by the spray pyrolysis method using the ultrasonic vibrator as a mist generator. The obtained particles were characterized. The mechanisms of particle formation were discussed in comparison with those if other particles, such as $BaTiO_3$, $ZnO_2$, ZnO ....., in the same spray pyrolysis process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.277-277
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• 2010

We present facile chemical route stabilizing dispersion of carboxylated single-Walled carbon nanotubes (SWCNTs) in ZnOsol prepared by using diethanolamine as a stabilizer. The dispersion was stabilized via capping of carboxyl groups on the SWCNT surface by a titania layer. We also demonstrated that the conductivity of the films prepared P3/$TiO_2$/ZnO as enhanced by therml treatment, and the thermal stbility of the film improved hybridization with ZnO sol pristine P3, P3/$SiO_2$ and P3/$TiO_2$ hybrid films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.41-41
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• 2010

We present facile chemical route stabilizing dispersion of carboxylated single-walled carbon nanotubes (SWCNTs) in ZnOsol prepared by using diethanolamine as a stabilizer. The dispersion was stabilized via capping of carboxyl groups on the SWCNT surface by a titania layer. We also demonstrated that the conductivity of the films prepared P3/$TiO_2$/ZnO as enhanced by therml treatment, and thethermal stbility of the film improved hybridization with ZnO sol pristine P3, P3/$SiO_2$ and P3/$TiO_2$ hybrid films.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.4
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• pp.177-183
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• 2016

Sewage treatment using microorganisms is affected by multiple factors such as microbial properties, characteristics of sewage and operating conditions, and nanoparticles inflow may cause negative effects on sewage treatment system especially on the system stability and efficiency. It was studied to assess the toxic effects of nanoparticles on microorganism growth. The activated sludge in the sewage treatment plant of university was cultured in the optimized medium for each strain. Bacillus (gram-positive), Pseudomonas and E.coli (gram-negative) in the activated sludge were selected as target microorganisms, and ZnO and $TiO_2$ were chosen as nanoparticles. For same concentration of nanoparticles, average growth inhibition rate of Bacillus was 60% or more, while that of Pseudomonas was less than 10%. The toxicity of nanoparticles was shown to be higher for gram-positive bacteria than gram-negative bacteria because of their differences on structure of cell wall, components of cell wall protein, physiology of cells and metabolism. ZnO affected 3 times more negative on the growth of microorganisms as compared to $TiO_2$. It was assumed that, therefore, toxicity of ZnO was found to be greater than $TiO_2$.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.189.2-189
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• 2003